So Chung

Effects of body composition, leptin, and adiponectin on bone mineral density in prepubertal girls.

Body weight is positively associated with bone mineral density but the relationship between obesity and bone mineral density is unclear. Leptin and adiponectin are potential independent contributors to bone mineral density. We assessed the correlations of body composition, leptin and adiponectin with bone mineral density, and whether leptin, adiponectin and body composition determine bone mineral density independently in prepubertal girls. Forty-eight prepubertal girls were classified into obese and control groups by body mass index. Serum leptin and adiponectin levels were determined by enzyme immunoassay. Bone mineral density was measured using dual energy radiography absorptiometry and body composition was measured using bioelectrical impedance analysis. Lean and fat mass, and leptin were positively correlated with bone mineral density. Lean mass was a positive independent predictor of femoral and L-spine bone mineral density. Serum leptin was a postivie independent predictor of femoral bone mineral density. Fat mass was a negative independent predictor of femoral bone mineral density. In prepubertal girls, lean mass has a favorable effect on bone mineral density. Fat mass seems not to protect the bone structure against osteoporosis, despite increased mechanical loading. Serum leptin may play a biological role in regulating bone metabolism.

Reference values for serum levels of insulin-like growth factor-I and insulin-like growth factor binding protein-3 in Korean children and adolescents.

OBJECTIVE Measurements of serum insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) are utilized in the diagnostic work-up and clinical management of children with growth disorders. We designed this study to establish the reference values of serum IGF-I and IGFBP-3 levels according to age, sex and pubertal stage in Korean children and adolescents. METHODS For the study, 1378 healthy Korean children and adolescents aged 0 to 17 years (722 boys, 656 girls) were randomly selected. Blood samples were collected, and the stored sera were assayed for IGF-I and IGFBP-3 using immunoradiometric assay (IRMA, Immunotech). The R 2.8.1 program (Bell Laboratories) was used to generate reference percentile curves for IGF-I and IGFBP-3 according to age, sex, and pubertal stage RESULTS Serum IGFBP-3 level was higher in girls compared to that in boys of the same ages throughout the pubertal period, whereas IGF-I was only higher for girls younger than 13 years of age. Serum levels of IGF-I and IGFBP-3 increased steadily with age in the prepubertal stage, followed by a progressive decline thereafter. Peak levels of serum IGF-I and IGFBP-3 were observed two years earlier in girls compared to those in boys (13 vs. 15 years of age, respectively). Serum IGF-I and IGFBP-3 concentrations were highest at Tanner stage IV in boys and girls, with a subsequent decline. CONCLUSIONS Our reference value model based on age, sex, and pubertal stage can improve the diagnostic utility of IGF-1 and IGFBP-3 levels in the evaluation and management of Korean children and adolescents with growth disorders.

Identification of a Novel Mutation in the ATP7A Gene in a Korean Patient with Menkes Disease

Menkes disease is an infantile-onset X-linked recessive neurodegenerative disorder caused by diverse mutations in a copper-transport gene, ATP7A. Affected patients are characterized by progressive hypotonia, seizures, failure to thrive and death in early childhood. Here, we report a case of Menkes disease presented by intractable seizures and infantile spasms. A 3-month-old male infant had visited our pediatric clinic for lethargy, floppy muscle tone, poor oral intake and partial seizures. His hair was kinky, brown colored and fragile. Partial seizures became more frequent, generalized and intractable to antiseizure medications. An EEG showed frequent posteriorly dominant generalized spikes that were consistent with a generalized seizure. From a genetic analysis, a c.2743C>T (p.Gln915X) mutation was detected and diagnosed as Menkes disease. The mutation is a novel one that has not been previously reported as a cause of Menkes disease.

Simultaneous Measurement of PPG and Functional MRI

The purpose of the current study was to develop a magnetic resonance (MR)-compatible photoplethysmograph (PPG) system which could measure the raw PPG signal during MR image acquisition. The system consisted of an optic sensor which measured the optic signal, an optic cable which transmitted a near-infrared optic signal, a signal amplifier, and a filter for noise removal. To minimize interactive noise, only the optic cable and the optic sensor module were located inside the MR room; the signal amplifier and filter were located outside the MR room. The experiment verified that a reliable PPG signal can be obtained without deteriorating the MR image. Especially, it was possible to get a reliable PPG signal while acquiring MR images with EPI method which has been used for functional magnetic resonance imaging (fMRI) study. This system can simultaneously measure the response of the central nervous system using fMRI and that of the peripheral nervous system using the PPG.

A Study of the Jerk Cost Function for Evaluating Quantitative Driving Performance during Simulated Driving

The purpose of this study was to test whether the jerk, the third derivative of the position, can be used as a quantitative driving performance index during simulated driving. Sixty healthy adults having 1-3 years driving experience were participated in driving simulator experiment. All subjects were instructed to keep constant distance from front vehicle running at 55~65km/hr speed on straight road. Each 10 males and 10 females were randomly selected in condition of keeping a constant distance with 20m, 25m and 30m, respectively. Experiment consisted of straight driving for 1 min and unexpected situation caused by emergency stop of the front vehicle. To collect 3D kinematic data, 10 markers were attached on the subjects’ upper (elbow, wrist and hand) and lower (knee, exterior knee, ankle, and toe) limbs and 3D motion capture system was synchronized with the driving simulator. The data was divided into unexpected situation section for 2 sec. To evaluate the driving performance, the jerk cost function (JCF) which indicates the smoothness of motion was calculated for all makers. The probability of collision was significantly smaller at the distance of 30m compared with 20m and 25m (p<.05). JCF of upper limbs did not show any significant patterns in distance between vehicles for unexpected section. However, JCF of lower limbs (knee, ankle and toe) showed significantly smaller values as the distance between vehicles was increased for unexpected situation section (p<.05). The probability of collision was decreased and the driving performance was increased with decreased JCF as the distance between vehicles was increased. Thus it can be concluded that JCF could be used as one of the parameters for evaluating the driving performance quantitatively.

Development of a Magnetic Resonance Compatible Motion Signal Measurement System

The purpose of this study was to develop 3-axis Magnetic Resonance (MR) compatible motion measurement system which can measure motion signals without deteriorating MR image. 3-axis accelerometer was used to measure motion signals and velcro was used to attach accelerometer module to finger or wrist. To minimize mutual interference effect between MR imaging system and motion measurement system, amplifier circuit was made of analog devices and amplifier was located at the shielded case which was made of copper and aluminum. Motion signal was modulated to optic signal by using Pulse Width Modulation (PWM) and modulated optic signal was transmitted to outside MR room by using Light Emitting Diode (LED) and optic cable. Measurement of 3-directional acceleration was possible with 3-axis accelerometer. It was verified that functional Magnetic Resonance imaging (fMRI) and motion signals were measured simultaneously and stably.

A Study on the Cerebral Lateralization Index using Intensity of BOLD Signal of functional Magnetic Resonance Imaging

This study proposes a new cerebral lateralization index on the basis of neural activation intensity. Eight right-handed male college students (mean age 23.5 years) and ten right-handed male college students (the mean age — 25.1 years) participated in this study of visuospatial and verbal tasks, respectively. Functional brain images were taken from 3T MRI using the single-shot EPI method. A cerebral lateralization index based on neural activation area (i.e. number of activated voxels) and another based on neural activation intensity (i.e. intensity of BOLD) were calculated for both cognition tasks. The result of calculating a cerebral lateralization index based on neural activation area suggested that the right hemisphere is dominant during visuospatial tasks and the left hemisphere is dominant during verbal tasks. When a cerebral lateralization index was computed on the basis of the neural activation intensity, it was shown that the area of cerebral lateralization closely related to visuospatial tasks is the superior parietal lobe, and the area of cerebral lateralization closely related to verbal tasks is the inferior and middle frontal lobes. Since the proposed method can determine the dominance of the cerebrum by each area, it can be helpful to determine cerebral lateralization accurately and easily.

Changes of Regional Activation to a Spatial Cognition Task with Aging: An fMRI Study

This study investigated the effect of aging on spatial cognition performance and regional brain activation. Eight right-handed male college students in their twenties (mean age 21.5 years) and six right-handed male adults in their forties (mean age 45.7 years) who were graduated from college participated in the study. A spatial task was presented while brain images were acquired by a 3T functional Magnetic Resonance Imaging (fMRI) system. Compared to the 40s the 20s showed higher spatial performance. Increased brain activations were observed in the parietal and superior frontal lobes at 20s compared to 40s. There was more activation observed in the middle frontal and right inferior frontal lobes at 40s compared to 20s.