• Korean Journal of Biological Psychiatry
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• v.24 no.2
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• pp.59-67
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• 2017

Shift workers experience a disruption in the circadian sleep-wake rhythm, which brings upon adverse health effects such as fatigue, insomnia and decreased sleep quality. Moreover, shift work has deleterious effects on both work productivity and safety. In this review, we present a brief overview of the current literature on the consequences of shift work, especially focusing on attention-associated cognitive decline and related behavioral changes. We searched two electronic databases, PubMed and RISS, using key search terms related to cognitive domains, deleterious effects, and shift work. Twenty studies were eligible for the final review. The consequences of shift work can be classified into the following three categories extracted from the literature review : 1) work accidents ; 2) commuting accidents such as car accidents that occur on the way to and from work ; and 3) attendance management at work (i.e., absenteeism, tardiness, and unscheduled early departure). These cognitive and behavioral consequences of shift work were also found to be associated with sleep disorders in shift workers. Thus, improvements in the shift work system are necessary in order to enhance workers' health conditions, work productivity, and safety.

• Journal of Biomedical Engineering Research
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• v.31 no.5
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• pp.412-416
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• 2010

In this study, we measured the chemical shift change of metabolite peaks in the brain-metabolite phantom according to the temperature variation using nuclear magnetic resonance(NMR). The temperature range in NMR system was controled from 25 to 80 (5 step) by internal temperature controller. Temperature coefficients of each metabolite peaks were also calculated from the measured chemical shift depending on the temperature. The chemical shift changes depending on temperature were validated by linear regression method for each metabolite peaks. The temperature coefficients of $_{tot}Cr$, Cho, Cr, NAA, and Lac were 0.0086, 0.0088, 0.0091, 0.0089, and 0.0088ppm/$^{\circ}C$, respectively. This study shows that chemical shift change of brain metabolite and temperature variation have linear relationship each other. This also makes authors believe that brain temperature measurement is possible using MR spectroscopic imaging technique.

• Journal of Korean Neurosurgical Society
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• v.38 no.5
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• pp.359-365
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• 2005

Objective : The study investigates the extent of brain shift and its effect on the accuracy of the stereotaxic procedure. Methods : Thirty-five patients underwent 40stereotactic procedures between June 2002 and March 2004. There were 26 males, mean age 59years old. There were 34procedures for Parkinson's disease, 2 for essential tremor, 3 for cerebral palsy, 1 for dystonia. Patients were divided in four groups based on postoperative pneumocephalus : under 5cc [9 procedures], between $5{\sim}10cc$ [13procedures], between $10{\sim}15cc$ [11 procedures] and more than 15cc [7procedures]. The coordinates of the anterior commissure[AC], posterior commissure[PC], and target were defined in pre-and intraoperative magnetic resonance image scans and the amount of air volume was measured with @Target (BrainLab, Heimstetten, Germany]. Results : The mean AC-PC was 26.5mm for patients with less than 5cc, 26.9mm for $5{\sim}10cc$, 25.8mm for $10{\sim}15cc$ and 26.2mm for more than 15cc. The length of AC-PC line and coordinates of AC, PC was also not statistically different, Euclidean distance as well as ${\Delta}x$, ${\Delta}y$, ${\Delta}z$ of AC, PC, and target were also not statistically different among the groups [p>,1]. There was a variance in target of $0.7{\sim}7.6mm$, Euclidean distance of 2.5mm, related to electrophysiology but not to brain-shift. Conclusion : The amount of air accumulated in the intracranial space and compressing the cortical surface has no effect on the localization of subcortical stereotactic target and landmarks.

• Investigative Magnetic Resonance Imaging
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• v.23 no.1
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• pp.38-45
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• 2019

Purpose: To demonstrate the high-resolution numerical simulation of the respiration-induced dynamic $B_0$ shift in the head using generalized susceptibility voxel convolution (gSVC). Materials and Methods: Previous dynamic $B_0$ simulation research has been limited to low-resolution numerical models due to the large computational demands of conventional Fourier-based $B_0$ calculation methods. Here, we show that a recently-proposed gSVC method can simulate dynamic $B_0$ maps from a realistic breathing human body model with high spatiotemporal resolution in a time-efficient manner. For a human body model, we used the Extended Cardiac And Torso (XCAT) phantom originally developed for computed tomography. The spatial resolution (voxel size) was kept isotropic and varied from 1 to 10 mm. We calculated $B_0$ maps in the brain of the model at 10 equally spaced points in a respiration cycle and analyzed the spatial gradients of each of them. The results were compared with experimental measurements in the literature. Results: The simulation predicted a maximum temporal variation of the $B_0$ shift in the brain of about 7 Hz at 7T. The magnitudes of the respiration-induced $B_0$ gradient in the x (right/left), y (anterior/posterior), and z (head/feet) directions determined by volumetric linear fitting, were < 0.01 Hz/cm, 0.18 Hz/cm, and 0.26 Hz/cm, respectively. These compared favorably with previous reports. We found that simulation voxel sizes greater than 5 mm can produce unreliable results. Conclusion: We have presented an efficient simulation framework for respiration-induced $B_0$ variation in the head. The method can be used to predict $B_0$ shifts with high spatiotemporal resolution under different breathing conditions and aid in the design of dynamic $B_0$ compensation strategies.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5857-5863
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• 2012

Introduction: Mobile phones are in extensive use worldwide and concerns regarding their role in tumor formation were raised. Over the years multiple studies were published in order to investigate this issue using several approaches. The current study looks at secular trends of brain gliomas (low and high grade) incidence and changes in tumor's laterality over 30 years in a population extensively using this technology with a possible correlation to the spread of use of mobile phones. Materials and Methods: All brain gliomas that were diagnosed from 1980-2009 were included and subdivided into two groups - low and high grade. Secular and periodic time trend analyses of incidence rates and changes in laterality were performed. Preferred side of head using mobile phones was assessed with a questionnaire in a sample of adult individuals. Results: A decrease in incidence of low grade giomas (LGG) that correlated with introduction of mobile technology was found from 2.57, 2.34 and 2.79 for every 100,000 in the period 1980 to the end of 1994 to 1.72, 1.82 and 1.57, respectively, over the last three 5-years periods (1995-2009). High-grade glioma incidences increased significantly from 1980-2009 but in the period after mobile phones were introduced (1994-2009) a lower, non significant, rate of increase was observed in males and a lower one (significant) in females. A shift towards left sided tumor location for all adult gliomas combined and separately for LGG and HGG was noted from 1995 onward. The shift was more marked for those who were diagnosed in ages 20-49 (p=0.03). Conclusions: We found a statistically significant decrease in LGG's over 30-years period that correlates with introducing of mobile phones technology and a shift in laterality towards left-sided tumors, the latter occurred in both low and high-grade gliomas.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.289-294
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• 2008

The purpose of this study is to materialize the viscosity sensor by using the SH-SAW sensor of which the center frequency is operated at higher than 50 MHz. In order to measure the viscosity, SAW sensor of which the center frequency is operated at 100 MHz is developed. By using the developed sensor, phase shift, delay time, insertion loss, and frequency variation are measured at different viscosity. The result shows that the phase shift difference between the viscosity variations is such that the difference between the distilled water and the 100 % glycerol solution is approximately $45^{\circ}$, the change of the insertion loss is approximately 9 dB, and the difference of frequency variation is approximately 5.9 MHz. Therefore, it is shown that viscosity of unknown solution can be measured with the surface acoustic wave sensor.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.4
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• pp.425-432
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• 2016

In addition to classical synaptic transmission, information is transmitted between cells via the activation of extrasynaptic receptors that generate persistent tonic current in the brain. While growing evidence supports the presence of tonic NMDA current ($I_{NMDA}$) generated by extrasynaptic NMDA receptors (eNMDARs), the functional significance of tonic $I_{NMDA}$ in various brain regions remains poorly understood. Here, we demonstrate that activation of eNMDARs that generate INMDA facilitates the ${\alpha}$-amino-3-hydroxy-5-methylisoxazole-4-proprionate receptor (AMPAR)-mediated steady-state current in supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs). In $low-Mg^{2+}$ artificial cerebrospinal fluid (aCSF), glutamate induced an inward shift in $I_{holding}$ ($I_{GLU}$) at a holding potential ($V_{holding}$) of -70 mV which was partly blocked by an AMPAR antagonist, NBQX. NBQX-sensitive $I_{GLU}$ was observed even in normal aCSF at $V_{holding}$ of -40 mV or -20 mV. $I_{GLU}$ was completely abolished by pretreatment with an NMDAR blocker, AP5, under all tested conditions. AMPA induced a reproducible inward shift in $I_{holding}$ ($I_{AMPA}$) in SON MNCs. Pretreatment with AP5 attenuated $I_{AMPA}$ amplitudes to ~60% of the control levels in $low-Mg^{2+}$ aCSF, but not in normal aCSF at $V_{holding}$ of -70 mV. $I_{AMPA}$ attenuation by AP5 was also prominent in normal aCSF at depolarized holding potentials. Memantine, an eNMDAR blocker, mimicked the AP5-induced $I_{AMPA}$ attenuation in SON MNCs. Finally, chronic dehydration did not affect $I_{AMPA}$ attenuation by AP5 in the neurons. These results suggest that tonic $I_{NMDA}$, mediated by eNMDAR, facilitates AMPAR function, changing the postsynaptic response to its agonists in normal and osmotically challenged SON MNCs.

• Journal of the Korea Safety Management & Science
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• v.15 no.2
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• pp.1-7
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• 2013

Based on a literature review regarding shift work, it is recognized that it has an adverse effect on workers' health. Especially, the night shift rather than the day shift imposes severe disorders on workers, which are indicated to dyssomnia, maladaptation to social life, and health problems such as gastroenteric trouble, cardiovascular diseases and depression. As the shift work can be explainable by using workers' labor ability necessarily to maintain company business consistently, it does not consider biorhythm, active mass and health condition of workers Actually duration of shit work would deprive workers of fundamental life rights by causing physical and mental effects. As a result of reviewing previous case studies related to effect of work pattern (day shift and night shift) on workers' health, an incidence of physical diseases like dyssomnia, gastroenteric trouble, cardiovascular diseases and premature delivery was higher in shift workers than normal workers. Additionally the incidence of mental disorders such as busy brain, social isolation, depression and work stress was also higher in shift workers than normal workers. These adverse physical and mental problems were intensified to night shift workers compared to day shift workers. Considering current various reports and study results, it is recommended that the shift work, especially the night work pattern, should not apply to contemporary work situation for sustaining workers' health condition constantly.

• Journal of Korean Neurosurgical Society
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• v.52 no.2
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• pp.80-84
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• 2012

Objective : This study analyzed the relationship between prognosis and multiple clinical factors of ruptured middle cerebral artery (MCA) aneurysm with intracerebral hemorrhage (ICH), to aid in predicting the results of surgical treatment. Methods : Enrolled subjects were 41 patients with ruptured MCA aneurysm with ICH who were treated with surgical clipping. Clinical factors such as gender, age, and initial Glasgow coma scale were assessed while radiological factors such as the volume and location of hematoma, the degree of a midline shift, and aneurysm size were considered retrospectively. Prognosis was evaluated postoperatively by Glasgow outcome scale. Results : Age and prognosis were correlated only in the groups with ICH over 31 mL or ICH at the frontal lobe or sylvian fissure. When initial mental status was good, only patients with ICH on the temporal lobe had a better prognosis. If the midline shift was less than 4.5 mm, the probability of better prognosis was 95.5% (21 of 22). If the midline shift was more than 4.5 mm, the probability of poor prognosis was 42.1% (8 of 19). Patients with ICH less than 31 mL had higher survival rates, whereas if the ICH was more than 31 mL, 41.2% (7 of 17) had a poor clinical pathway. Conclusion : Even if the initial clinical condition of the patient was not promising, by carefully examining and taking into account all factors, neurosurgeons can confidently recommend surgical treatment for these patients.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.730-737
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• 2017

Objective : Postoperative hydrocephalus is a common complication following craniectomy in patients with traumatic brain injury, and affects patients' long-term outcomes. This study aimed to verify the risk factors associated with the development of hydrocephalus after craniectomy in patients with acute traumatic subdural hemorrhage (tSDH). Methods : Patients with acute traumatic SDH who had received a craniectomy between December 2005 and January 2016 were retrospectively assessed by reviewing the coexistence of other types of hemorrahges, measurable variables on computed tomography (CT) scans, and the development of hydrocephalus during the follow-up period. Results : Data from a total of 63 patients who underwent unilateral craniectomy were analyzed. Postoperative hydrocephalus was identified in 34 patients (54%) via brain CT scans. Preoperative intraventricular hemorrhage (IVH) was associated with the development of hydrocephalus. Furthermore, the thickness of SDH (p=0.006) and the extent of midline shift before craniectomy (p=0.001) were significantly larger in patients with postoperative hydrocephalus. Indeed, multivariate analyses showed that the thickness of SDH (p=0.019), the extent of midline shift (p<0.001) and the coexistence of IVH (p=0.012) were significant risk factors for the development of postoperative hydrocephalus. However, the distance from the midline to the craniectomy margin was not an associated risk factor for postoperative hydrocephalus. Conclusion : In patients with acute traumatic SDH with coexisting IVH, a large amount of SDH, and a larger midline shift, close follow-up is necessary for the early prediction of postoperative hydrocephalus. Furthermore, craniectomy margin need not be limited in acute traumatic SDH patients for the reason of postoperative hydrocephalus.