• Journal of Astronomy and Space Sciences
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• v.39 no.1
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• pp.11-22
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• 2022

It is suggested that magnetosonic waves (also known as equatorial noise) can scatter radiation belt electrons in the Earth's magnetosphere. Therefore, it is important to understand the global distribution of these waves between the proton cyclotron frequency and the lower hybrid resonance frequency. In this study, we developed an empirical model for estimating the global distribution of magnetosonic wave amplitudes and wave normal angles. The model is based on the entire mission period (approximately 2012-2019) of observations of Van Allen Probes A and B as a function of the distance from the Earth (denoted by L^*), magnetic local time (MLT), magnetic latitude (λ), and geomagnetic activity (denoted by the Kp index). In previous studies the wave distribution inside and outside the plasmasphere were separately investigated and modeled. Our model, on the other hand, identifies the wave distribution along with the ambient plasma environment-defined by the ratio of the plasma frequency (f_pe) to the electron cyclotron frequency (f_ce)-without separately determining the wave distribution according to the plasmapause location. The model results show that, as Kp increases, the dayside wave amplitude in the equatorial region intensifies. It thereby propagates the intense region towards the wider MLT and inward to L^* < 4. In contrast, the f_pe/f_ce ratio decreases with increasing Kp for all regions. Nevertheless, the decreasing aspect differs between regions above and below L^* = 4. This finding implies that the particle energy and pitch angle that magnetosonic waves can effectively scatter vary depending on the locations and geomagnetic activity. Our model agrees with the statistically observed wave distribution and ambient plasma environment with a coefficient of determination of > 0.9. The model is valid in all MLTs, 2 ≤ L^* < 6, |λ| < 20°, and Kp ≤ 6.

• Journal of Genetic Medicine
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• v.18 no.2
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• pp.127-131
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• 2021

Autosomal recessive spinocerebellar ataxia 20 (SCAR20; OMIM #616354) is a recently described disorder that is characterized by ataxia, intellectual disability, cerebellar atrophy, macrocephaly, coarse face, and absent speech. It is caused by loss-of-function mutations in SNX14. To date, all cases with homozygous pathogenic variants have been identified in consanguineous families. This report describes the first Korean cases of SCAR20 family caused by homozygous variants in SNX14. Two siblings were referred to our clinic because of severe global developmental delay. They presented similar facial features, including a high forehead, long philtrum, thick lips, telecanthus, depressed nasal bridge, and broad base of the nose. Because the older sibling was unable to walk and newly developed ataxia, repeated brain magnetic resonance imaging (MRI) was performed at the age of 4 years, revealing progressive cerebellar atrophy compared with MRI performed at the age of 2 years. The younger sibling's MRI revealed a normal cerebellum at the age of 2 years. Whole-exome sequencing was performed, and homozygous variants, such as c.2746-2A>G, were identified in SNX14 from the older sibling. Sanger sequencing confirmed homozygous SNX14 variants in the two siblings as well as a heterozygous variant in both parents. This report extends our knowledge of the phenotypic and mutational spectrum of SCAR20. We also highlight the importance of deep phenotyping for the diagnosis of SCAR20 in individuals with developmental delay, ataxia, cerebellar atrophy, and distinct facial features.

• Pediatric Infection and Vaccine
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• v.29 no.1
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• pp.54-60
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• 2022

Salmonella meningitis is rare yet poses causes significant neurological morbidity in children. Infants, especially those under 3 months of age, and those with immunocompromised states, such as malignancy, malaria, and human immunodeficiency virus infection, are at increased risk for developing Salmonella meningitis. Herein, we describe a case of Salmonella meningitis in a previous healthy 8-year-old girl who presented with high fever, vomiting, and altered mental status. Group D Salmonella species were isolated in cerebrospinal fluid culture, and no abnormal findings were noted in brain magnetic resonance imaging. Immunoglobulin levels and lymphocyte subset counts were within the normal ranges, and no genetic mutation responsible for primary immunodeficiency disease was detected by next-generation sequencing. The patient's condition improved rapidly with third-generation cephalosporin, and no complications or sequalae developed. Nontyphoidal Salmonella can cause meningitis in immunocompetent children and can be successfully treated with early administration of antibiotics.

• Journal of Biomedical Engineering Research
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• v.44 no.1
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• pp.53-63
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• 2023

There have been many studies from the genetic system to physical activity and emotional expression such that there are gender differences. The purpose of this study was to determine how the structural characteristics of cortical thickness differ between males and females. This study used data from the Human Connectome Project (HCP). To analyze age-specific sexual dimorphisms of cortical thickness, selected 8-80 year old subjects were divided into five detailed age range groups according to each criterion. A total of 1,700 individual brain MRI T1 data were registered in stereotaxic space for analysis and classified into white matter (WM), gray matter (GM), and cerebro-spinal fluid (CSF). For surface-based analysis, the WM/GM surface was reconstructed from a spherical polygon model with 40962 vertices per hemisphere, and each vertex was extended to the GM/CSF boundary. Cortical thickness was then measured between each vertex using the t-link method. In the statistical analysis, intracranial volume was used as a covariate to exclude the effect of the difference in brain size of each individual, and the result of using age as a covariate was added to confirm the age effect within each group. Gender differences in cortical thickness had significant results by group. This may be an index to explain diseases with sexual dimorphism in prevalence or become a basis for explaining the characteristics of each sex that appear in behavior, personality, and aging. Therefore, the results of our study could be a criterion for age classification in future studies and for understanding 'normal' sexual dimorphism.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.193-198
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• 2022

Contrast enhanced magnetic resonance imaging using gadolinium-based contrast agent (GBCA) is a very useful in vivo technique to visualize the inner ear pathology including endolymphatic hydrops. Although systemic intravenous (IV) administration can visualize the perilymph space, the visualization was possible by indirect passage of contrast agent through blood-perilymph barrier. All animal experimental procedures were performed under anesthesia with 5% isoflurane. Lipopolysaccharide (LPS) was instilled into the left tympanic cavity through the tympanic membrane using a sterile 27gauge needle to induce hydrops model. Tucker-Davis Technologies system was used to measure Auditory Brainstem Responses (ABRs). For intracerebroven-tricular (ICV) administration, 25 µmol of GADOVIST (Bayer, Berlin, Germany) was used and diluted GADOVIST injection was 10 µl. MR imaging was acquired with a 9.4 Tesla MRI scanner. Transmit-receive volume coil with 40 mm inner diameter and 75 mm out diameter was used. ICV administration well demonstrated the strong enhancement along the cerebrospinal fluid (CSF) microcirculation pathway including CSF fluid in the subarachnoid space and CSF space of the inner ear structures. On the other hand, IV administration showed no contrast enhancement along the CSF microcirculation pathway and showed weak enhancement in the inner ear structures. In case of rat hydrops model, ICV administration showed that the reduced contrast enhancement in the perilymph space of the hydrops induced inner ear compared to the contrast enhancement in the perilymph space of the normal inner ear. New systemic ICV administration method provide contrast enhancement of GBCA in the inner ear through CSF microcirculation pathway.

• Pediatric Infection and Vaccine
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• v.29 no.3
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• pp.173-178
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• 2022

Streptococcus intermedius is a small, non-motile, Gram-positive, non-sporeforming, and aerotolerant anaerobic coccus. It is a part of the normal microflora in the oral cavity and upper respiratory, gastrointestinal and female urogenital tracts. It is an opportunistic pathogen that causes serious infections in patients with immunocompromised states or cardiac diseases as a result of trauma or invasive procedures. We describe a case of septic arthritis of the hip caused by S. intermedius in an immunocompetent healthy 7-year-old boy without a history of periodontal disease or invasive procedures. He had hip joint pain three weeks ago, and the fever began on the day of the visit. He had been healthy and had not undergone any invasive procedures recently. Septic arthritis of the hip was indicated in the magnetic resonance imaging of the hip. S. intermedius was identified in the hip joint fluid aspiration and blood culture. He was successfully treated with surgical intervention and antibiotic therapy with ceftriaxone followed by amoxicillin for five weeks.

• Korean Journal of Veterinary Service
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• v.46 no.1
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• pp.87-92
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• 2023

A 7-year-old dog weighing 3.9 kg visited the hospital with symptoms of inability to stand and quadriparesis. There were seizure symptoms 2 months before admission to the hospital, and the symptoms of stiffness and rigidity appeared. Radiographs showed normal vertebrae in cervical vertebral column. Magnetic resonance imaging (MRI) and computed tomography (CT) were performed immediately to diagnose vertebral lameness. As a result of the CT, it was possible to observe the fracture of the odontoid process of the axis, and the exact location of the damage was identified. The odontoid process was fractured and separated from the body of the 2^nd cervical vertebra (axis), and fragment of the process was observed inside the vertebral arch of the first cervical vertebra (atlas), and the body of the axis was lifted to the dorsal side. The MRI examination reflected the CT findings and confirmed severe spinal cord compression due to the fracture of the odontoid process. The patient was applied by neck brace and medical management including Mycophenolate mofetil administration was performed. The patient was able to move legs and tail after 2 weeks, and was able to voluntarily defecate, urinate and stand up after 4 weeks of administration.

• Journal of Korean Neurosurgical Society
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• v.66 no.6
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• pp.735-742
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• 2023

Nephrotic syndrome (NS) is associated with cerebral venous sinus thrombosis (CVST), which is a rare cerebrovascular disorder in children. Systemic anticoagulation with heparin is the standard therapy for CVST, and mechanical thrombectomy (MT) has been described as a salvage treatment for adult anticoagulant refractory CVST, However, it has never been reported in children. We describe a case of MT for refractory CVST in a child with NS. A 13-year-old boy with newly diagnosed NS presented to an emergency department with acute headache. A head computed tomography showed acute thrombus in the superior sagittal sinus, straight sinus and transverse sinus. The child was started on heparin therapy, but clinically deteriorated and became unresponsive. In view of the rapid deterioration of the condition after anticoagulation treatment, the patient received intravascular treatment. Several endovascular technologies, such as stent retriever and large bore suction catheter have been adopted. After endovascular treatment, the patient's neurological condition was improved within 24 hours, and magnetic resonance venography of the head demonstrated that the CVST was reduced. The child recovered with normal neurological function at discharge. This case highlights the importance of considering MT for refractory CVST, and we suggest that MT may be considered for refractory CVST with NS in children.

• Korean Journal of Radiology
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• v.22 no.3
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• pp.405-414
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• 2021

Objective: To compare two clinically available MR volumetry software, NeuroQuant^® (NQ) and Inbrain^® (IB), and examine the inter-method reliabilities and differences between them. Materials and Methods: This study included 172 subjects (age range, 55-88 years; mean age, 71.2 years), comprising 45 normal healthy subjects, 85 patients with mild cognitive impairment, and 42 patients with Alzheimer's disease. Magnetic resonance imaging scans were analyzed with IB and NQ. Mean differences were compared with the paired t test. Inter-method reliability was evaluated with Pearson's correlation coefficients and intraclass correlation coefficients (ICCs). Effect sizes were also obtained to document the standardized mean differences. Results: The paired t test showed significant volume differences in most regions except for the amygdala between the two methods. Nevertheless, inter-method measurements between IB and NQ showed good to excellent reliability (0.72 < r < 0.96, 0.83 < ICC < 0.98) except for the pallidum, which showed poor reliability (left: r = 0.03, ICC = 0.06; right: r = -0.05, ICC = -0.09). For the measurements of effect size, volume differences were large in most regions (0.05 < r < 6.15). The effect size was the largest in the pallidum and smallest in the cerebellum. Conclusion: Comparisons between IB and NQ showed significantly different volume measurements with large effect sizes. However, they showed good to excellent inter-method reliability in volumetric measurements for all brain regions, with the exception of the pallidum. Clinicians using these commercial software should take into consideration that different volume measurements could be obtained depending on the software used.

• Korean Journal of Radiology
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• v.2 no.4
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• pp.192-196
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• 2001

Objective: To compare conventional and diffusion-weighted MR imaging in terms of their depiction of the abnormalities occurring in Creutzfeldt-Jakob disease. Materials and Methods: We retrospectively analyzed the findings of conventional (T2-weighted and fluid-attenuated inversion recovery) and diffusion-weighted MR imaging in four patients with biopsy-proven Creutzfeldt-Jakob disease. The signal intensity of the lesion was classified by visual assessment as markedly high, slightly high, or isointense, relative to normal brain parenchyma. Results: Both conventional and diffusion-weighted MR images demonstrated bilateral high signal intensity in the basal ganglia in all four patients. Cortical lesions were observed on diffusion-weighted MR images in all four, and on fluid-attenuated inversion recovery MR images in one, but in no patient on T2-weighted images. Conventional MR images showed slightly high signal intensity in all lesions, while diffusion-weighted images showed markedly high signal intensity in most. Conclusion: Diffusion-weighted MR imaging is more sensitive than its conventional counterpart in the depiction of Creutzfeldt-Jakob disease, and permits better detection of the lesion in both the cerebral cortices and basal ganglia.