Association of Visceral Fat Obesity, Sarcopenia, and Myosteatosis with Non-Alcoholic Fatty Liver Disease without Obesity

Background/Aims@#To investigate whether non-alcoholic fatty liver disease (NAFLD) in individuals without generalized obesity is associated with visceral fat obesity (VFO), sarcopenia, and/or myosteatosis. @*Methods@#This cross-sectional analysis included 14,400 individuals (7,470 men) who underwent abdominal computed tomography scans during routine health examinations. The total abdominal muscle area (TAMA) and skeletal muscle area (SMA) at the 3rd lumbar vertebral level were measured. The SMA was divided into the normal attenuation muscle area (NAMA) and low attenuation muscle area, and the NAMA/TAMA index was calculated. VFO was defined by visceral to subcutaneous fat ratio, sarcopenia by body mass index-adjusted SMA, and myosteatosis by the NAMA/TAMA index. NAFLD was diagnosed with ultrasonography. @*Results@#Of the 14,400 individuals, 4,748 (33.0%) had NAFLD, and the prevalence of NAFLD among non-obese individuals was 21.4%. In regression analysis, both sarcopenia (men: odds ratio [OR] 1.41, 95% confidence interval [CI] 1.19–1.67, P<0.001; women: OR=1.59, 95% CI 1.40–1.90, P<0.001) and myosteatosis (men: OR=1.24, 95% CI 1.02–1.50, P=0,028; women: OR=1.23, 95% CI 1.04–1.46, P=0.017) were significantly associated with non-obese NAFLD after considering for VFO and other various risk factors, whereas VFO (men: OR=3.97, 95% CI 3.43–4.59 [adjusted for sarcopenia], OR 3.98, 95% CI 3.44–4.60 [adjusted for myosteatosis]; women: OR=5.42, 95% CI 4.53–6.42 [adjusted for sarcopenia], OR=5.33, 95% CI 4.51–6.31 [adjusted for myosteatosis]; all P<0.001) was strongly associated with non-obese NAFLD after adjustment with various known risk factors. @*Conclusions@#In addition to VFO, sarcopenia and/or myosteatosis were significantly associated with non-obese NAFLD.

Sex Differences of Visceral Fat Area and Visceral-to-Subcutaneous Fat Ratio for the Risk of Incident Type 2 Diabetes Mellitus

Background@#This study aimed to determine the optimal cut-off values of visceral fat area (VFA) and visceral-to-subcutaneous fat ratio (VSR) for predicting incident type 2 diabetes mellitus (T2DM). @*Methods@#A total of 10,882 individuals (6,835 men; 4,047 women) free of T2DM at baseline aged between 30 and 79 years who underwent abdominal computed tomography scan between 2012 and 2013 as a part of routine health check-ups were included and followed. VFA, subcutaneous fat area, and VSR on L3 vertebral level were measured at baseline. @*Results@#During a median follow-up of 4.8 years, 730 (8.1% for men; 4.3% for women) incident cases of T2DM were identified. Receiver operating characteristic curve analysis showed that the optimal cut-off values of VFA and VSR for predicting incident T2DM were 130.03 cm2 and 1.08 in men, respectively, and 85.7 cm2 and 0.48 in women, respectively. Regardless of sex, higher VFA and VSR were significantly associated with a higher risk of incident T2DM. Compared with the lowest quartiles of VFA and VSR, the highest quartiles had adjusted odds ratios of 2.62 (95% confidence interval [CI], 1.73 to 3.97) and 1.55 (95% CI, 1.14 to 2.11) in men, respectively, and 32.49 (95% CI, 7.42 to 142.02) and 11.07 (95% CI, 3.89 to 31.50) in women, respectively. @*Conclusion@#Higher VFA and VSR at baseline were independent risk factors for the development of T2DM. Sex-specific reference values for visceral fat obesity (VFA ≥130 cm2 or VSR ≥1.0 in men; VFA ≥85 cm2 or VSR ≥0.5 in women) are proposed for the prediction of incident T2DM.

Gender-Dependent Reference Range of Serum Calcitonin Levels in Healthy Korean Adults

Background@#Serum calcitonin measurement contains various clinical and methodological aspects. Its reference level is wide and unclear despite sensitive calcitonin kits are available. This study aimed to identify the specific reference range in the healthy Korean adults. @*Methods@#Subjects were ≥20 years with available calcitonin (measured by a two-site immunoradiometric assay) data by a routine health checkup. Three groups were defined as all eligible subjects (group 1, n=10,566); subjects without self or family history of thyroid disease (group 2, n=5,152); and subjects without chronic kidney disease, autoimmune thyroid disease, medication of proton pump inhibitor/H2 blocker/steroid, or other malignancies (group 3, n=4,638). @*Results@#This study included 6,341 male and 4,225 female subjects. Males had higher mean calcitonin than females (2.3 pg/mL vs. 1.9 pg/mL, P<0.001) in group 1. This gender difference remained similar in groups 2 and 3. Calcitonin according to age or body mass index was not significant in both genders. Higher calcitonin in smoking than nonsmoking men was observed but not in women. Sixty-nine subjects had calcitonin higher than the upper reference limit (10 pg/mL) and 64 of them had factors associated with hypercalcitoninemia besides medullary thyroid cancer. Our study suggests the reference intervals for men who were non, ex-, current smokers, and women (irrespective of smoking status) as <5.7, <7.1, <7.9, and <3.6 pg/mL, respectively. @*Conclusion@#Specific calcitonin reference range should be provided considering for sex and smoking status. Taking account for several factors known to induce hypercalcitoninemia can help interpret the gray zone of moderately elevated calcitonin.

Gender-Dependent Reference Range of Serum Calcitonin Levels in Healthy Korean Adults

Background@#Serum calcitonin measurement contains various clinical and methodological aspects. Its reference level is wide and unclear despite sensitive calcitonin kits are available. This study aimed to identify the specific reference range in the healthy Korean adults. @*Methods@#Subjects were ≥20 years with available calcitonin (measured by a two-site immunoradiometric assay) data by a routine health checkup. Three groups were defined as all eligible subjects (group 1, n=10,566); subjects without self or family history of thyroid disease (group 2, n=5,152); and subjects without chronic kidney disease, autoimmune thyroid disease, medication of proton pump inhibitor/H2 blocker/steroid, or other malignancies (group 3, n=4,638). @*Results@#This study included 6,341 male and 4,225 female subjects. Males had higher mean calcitonin than females (2.3 pg/mL vs. 1.9 pg/mL, P<0.001) in group 1. This gender difference remained similar in groups 2 and 3. Calcitonin according to age or body mass index was not significant in both genders. Higher calcitonin in smoking than nonsmoking men was observed but not in women. Sixty-nine subjects had calcitonin higher than the upper reference limit (10 pg/mL) and 64 of them had factors associated with hypercalcitoninemia besides medullary thyroid cancer. Our study suggests the reference intervals for men who were non, ex-, current smokers, and women (irrespective of smoking status) as <5.7, <7.1, <7.9, and <3.6 pg/mL, respectively. @*Conclusion@#Specific calcitonin reference range should be provided considering for sex and smoking status. Taking account for several factors known to induce hypercalcitoninemia can help interpret the gray zone of moderately elevated calcitonin.

Sarcopenia and Muscle Aging: A Brief Overview

The world is facing the new challenges of an aging population, and understanding the process of aging has therefore become one of the most important global concerns. Sarcopenia is a condition which is defined by the gradual loss of skeletal muscle mass and function with age. In research and clinical practice, sarcopenia is recognized as a component of geriatric disease and is a current target for drug development. In this review we define this condition and provide an overview of current therapeutic approaches. We further highlight recent findings that describe key pathophysiological phenotypes of this condition, including alterations in muscle fiber types, mitochondrial function, nicotinamide adenine dinucleotide (NAD+) metabolism, myokines, and gut microbiota, in aged muscle compared to young muscle or healthy aged muscle. The last part of this review examines new therapeutic avenues for promising treatment targets. There is still no accepted therapy for sarcopenia in humans. Here we provide a brief review of the current state of research derived from various mouse models or human samples that provide novel routes for the development of effective therapeutics to maintain muscle health during aging.

Sarcopenia and Muscle Aging: A Brief Overview

The world is facing the new challenges of an aging population, and understanding the process of aging has therefore become one of the most important global concerns. Sarcopenia is a condition which is defined by the gradual loss of skeletal muscle mass and function with age. In research and clinical practice, sarcopenia is recognized as a component of geriatric disease and is a current target for drug development. In this review we define this condition and provide an overview of current therapeutic approaches. We further highlight recent findings that describe key pathophysiological phenotypes of this condition, including alterations in muscle fiber types, mitochondrial function, nicotinamide adenine dinucleotide (NAD+) metabolism, myokines, and gut microbiota, in aged muscle compared to young muscle or healthy aged muscle. The last part of this review examines new therapeutic avenues for promising treatment targets. There is still no accepted therapy for sarcopenia in humans. Here we provide a brief review of the current state of research derived from various mouse models or human samples that provide novel routes for the development of effective therapeutics to maintain muscle health during aging.

Age-Related Decrease in Skeletal Muscle Mass Is an Independent Risk Factor for Incident Nonalcoholic Fatty Liver Disease: A 10-Year Retrospective Cohort Study

BACKGROUND/AIMS: Sarcopenia has emerged as an important risk factor for nonalcoholic fatty liver disease (NAFLD). Although aging is the main cause of sarcopenia, the longitudinal association between age-related body composition changes and NAFLD development has not been fully investigated. Thus, we evaluated whether age-related increased fat mass or decreased muscle mass is an independent risk factor for incident NAFLD. METHODS: We conducted a retrospective cohort study involving 4,398 initially NAFLD-free subjects who underwent routine health examinations during 2004 to 2005 and returned for a follow-up during 2014 to 2015. Their body composition was measured by bioelectrical impedance analysis, and fatty liver was diagnosed by abdominal ultrasonography. RESULTS: At the 10-year follow-up, 591 out of 4,398 participants (13.4%) had developed NAFLD. In men and women, both increased fat mass and decreased appendicular skeletal muscle mass (ASM) with aging were significantly associated with incident NAFLD after adjustment. A subgroup analysis according to the baseline obesity status showed that increased fat mass was significantly associated with incident NAFLD in obese and nonobese subjects. However, decreased ASM was significantly associated with incident NAFLD in nonobese but not in obese subjects. According to ΔASM tertiles (decrease of ASM), the odds ratios for incident NAFLD in nonobese subjects were 1.38 (95% confidence interval [CI], 1.04 to 1.84) for the second tertile and 1.81 (95% CI, 1.34 to 2.45) for the third tertile after adjustment (p=0.001). CONCLUSIONS: A progressive increase in fat mass and a loss of ASM with aging were significantly associated with incident NAFLD. This association was more prominent in nonobese subjects.

Longitudinal Changes of Body Composition Phenotypes and Their Association with Incident Type 2 Diabetes Mellitus during a 5-Year Follow-up in Koreans

BACKGROUND: To elucidate longitudinal changes of complex body composition phenotypes and their association with incident type 2 diabetes mellitus. METHODS: A total of 17,280 (mean age, 48.1±8.2 years) Korean adults who underwent medical check-ups were included. The mean follow-up duration was 5.5±0.5 years. Body compositions were assessed using a bioelectrical impedance analysis. Four body composition phenotypes were defined using the median of appendicular skeletal muscle mass (ASM) index and fat mass index: low muscle/low fat (LM/LF); high muscle (HM)/LF; LM/high fat (HF); and HM/HF groups. RESULTS: Of the individuals in the LM/LF or HM/HF groups, over 60% remained in the same group, and over 30% were moved to the LM/HF group. Most of the LM/HF group remained in this group. In the baseline HM/LF group, approximately 30% stayed in the group, and the remaining individuals transitioned to the three other groups in similar proportions. Incident diabetes was significantly lower in participants who remained in the HM/LF group than those who transitioned to the LM/LF or LM/HF group from the baseline HM/LF group in men. ASM index was significantly associated with a decreased risk for incident diabetes in men regardless of obesity status (adjusted odds ratio [OR], 0.71 per kg/m²; 95% confidence interval [CI], 0.52 to 0.97 in non-obese) (adjusted OR, 0.87; 95% CI, 0.77 to 0.98 in obese) after adjusting for other strong risk factors (e.g., baseline glycosylated hemoglobin and homeostasis model assessment of insulin resistance). CONCLUSION: Maintenance of ASM may be protective against the development of type 2 diabetes mellitus in men, regardless of obesity status.

Survey of Activated Charcoal Administration for Poisoning Patients Visited in Emergency Medical Centers and Emergency Staff's Perception in Korea

PURPOSE: Activated charcoal (AC) has been widely used as a universal antidote. Currently, emergency medical centers in Korea cannot administer AC due to discontinuation of the supply of commercial ready-mixed AC suspension. This study was conducted to investigate the proportion of emergency medical centers that administer AC to poisoning patients and provide basic information for emergency physicians and toxicologists. METHODS: A prospective telephone survey of all of the included emergency medical institutions was conducted. The type of emergency medical institution, average annual number of patients admitted to the emergency department, annual average number of patients who were poisoned and whether the hospital currently utilizes gastric lavage and administration of AC were determined. RESULTS: AC was administered to poisoning patients in 40% of regional emergency medical centers, 59.3% of local emergency medical centers, and 45.9% of local emergency medical rooms. Overall, 37% of total emergency medical institutions did not administer AC due to discontinuation of the commercial ready-mixed AC suspension. Additionally, 77% of emergency physicians in institutions without AC knew AC is necessary for poisoning patients. The rate of vomiting experienced by the medical staff according to types of charcoal showed that the average rate of vomiting was 33% for commercial ready-mixed activated charcoal suspension and 51% for self-prepared charcoal powder (p=0.02). CONCLUSION: AC should be secured promptly in emergency medical institutions. Before the supply of commercial ready-mixed AC suspension becomes again it is essential to develop a standardized regimen for self-preparation of charcoal powder and to educate emergency physicians and toxicologists to its use.

Serum vitamin D3 levels are not associated with thyroid cancer prevalence in euthyroid subjects without autoimmune thyroid disease

BACKGROUND/AIMS: Previous studies have suggested that elevated serum vitamin D levels might protect against thyroid cancer. Elevated serum thyroid stimulating hormone levels and autoimmune thyroid disease (AITD) are suggested to be thyroid cancer promoting factors but have not been well controlled in previous studies. We designed the present study to evaluate whether serum vitamin D levels are associated with thyroid cancer in euthyroid patients with no clinical evidence of AITD. METHODS: This cross-sectional study included subjects who underwent routine health check-ups, including serum 25-hydroxy vitamin D3 (25(OH)D3) levels, anti-thyroid peroxidase antibody (TPO-Ab), and thyroid ultrasonography (US). Inclusion criteria were euthyroid, negative TPO-Ab, and no evidence of AITD by US findings. Thyroid cancer diagnoses were based on fine needle aspiration cytology and/or postsurgical histopathological findings. RESULTS: We enrolled 5,186 subjects (64% male, 37% female) in this study, including 53 patients (1%) with a diagnosis of thyroid cancer (33 males, 20 females). Mean 25(OH)D3 levels were similar between the thyroid cancer and control groups (p = 0.20). Subgroup analysis according to sex or seasonal variation also revealed no differences in 25(OH)D3 levels between the two groups. Based on the levels of 25(OH)D3, there was no significant difference in the prevalence of thyroid cancer; the prevalence was 0.71%, 0.94%, 1.40%, and 0.82% in the deficient, insufficient, sufficient, and excess groups, respectively (p = 0.64). CONCLUSIONS: The levels of serum 25(OH)D3 are not associated with thyroid cancer prevalence in euthyroid subjects with no clinical evidence of AITD.

Analysis of Drug Utilization in Patients with Chronic Hepatitis B

BACKGROUND: The treatment goal for patients with chronic hepatitis B infection is to prevent progression of the disease to cirrhosis and hepatocellular carcinoma. Current therapies include standard and pegylated interferon-alfa and nucleoside/nucleotide analogues: lamivudine, adefovir, entecavir, telbivudine, clevudine, and tenofovir. This study aims to analyze changes in the prescribing patterns of chronic hepatitis B (CHB) medications in South Korea between 2013 and 2014. METHODS: A cross-sectional study was conducted using National Patients Sample data compiled by the Health Insurance Review and Assessment Service from 2013 and 2014. Patients with CHB were identified with Korean Standard Classification of Diseases code-6 (B18.0 and B18.1) and those who were maintaining active prescriptions with CHB medications covering the index date (December 1(st), each year) were included. The utilization of antiviral therapy was investigated during 2013 and 2014. RESULTS: A total of 4,204 and 4,552 patients in 2013 and 2014 respectively, were included in the analysis. The proportion of male patients was two of third and the patients 41-60 years old accounted for 60% of all analyzed patients. The most utilized drug was entecavir (55.1% in 2013 and 44.8% in 2014) and the second most utilized drug was tenofovir in both years (18.8% in 2013 and 29.0% in 2014). The percentage of combination therapy was 13.6% and 13.1% in 2013 and 2014, respectively. The proportion of tenofovir prescriptions was increased in 2014 compared with 2013. CONCLUSION: With the development of new drugs and the changes in clinical practice guidelines, the prescription pattern of the antiviral agents for patients with CHB has changed. The rate of utilization of tenofovir has increased.

Association between Serum Gamma-Glutamyl Transferase and Thyroid Cancer in an Ultrasonographically Screened Population / 대한갑상선학회지

BACKGROUND AND OBJECTIVES: We reported recently a positive correlation between obesity and thyroid cancer in women. Serum gamma-glutamyl transferase (GGT) is regarded as a marker of exposure to environmental pollutants, cancer-causing xenobiotic. This study was conducted to evaluate the mechanism behind the association of obesity with thyroid cancer. We hypothesized serum GGT may be a surrogate for persistent organic pollutants to explain the connection between obesity and thyroid cancer. MATERIALS AND METHODS: We obtained data from 15,131 subjects who underwent a routine health checkup including thyroid ultrasonography from 2007 to 2008 at the Health Screening and Promotion Center of Asan Medical Center. Suspicious nodules were examined by ultrasonography-guided aspiration. Those with a history of hepatobiliary disease and abnormal result of liver function test were excluded. Serum GGT cut-off points were the 25th, 50th, and 75th sex-specific percentiles. RESULTS: A total of 15,131 subjects (7662 men and 7469 women) were screened by thyroid ultrasonography. Thyroid cancers were diagnosed in 260 patients. After adjustment of age, smoking status, alcohol intake, body mass index, compared with the lowest serum GGT quartile, odds ratios (95% confidence intervals) of risk of thyroid cancer were 0.54 (0.28-0.99) for 2nd quartile, 0.92 (0.56-1.50) for 3rd quartile, and 0.61 (0.34-1.09) for 4th quartile in men. In women, the adjusted odds ratios were 1.06 (0.66-1.72), 1.18 (0.77-1.85), and 0.63 (0.38-1.06) for the 2nd, 3rd, and 4th quartile, respectively. CONCLUSION: Elevated GGT is not associated with a higher prevalence of thyroid cancer in either gender when evaluated in a routine health checkup setting.

Relationship of Simple Renal Cyst to Hypertension / 가정의학회지

BACKGROUND: Simple renal cyst is the most common cystic deformation found in adults. However, there were a few systematic Korean reports for the clinical symptoms and complications of simple renal cysts. The author's purpose was to determine the relationship between simple renal cysts diagnosed by abdominal ultrasonography and hypertension. METHODS: Among 13,482 persons who took a routine physical examination at Ulsan University Hospital in 2002, 5,127 persons who took medical examinations again in 2010 were selected. We excluded persons who had renal cyst, hypertension, diabetes, liver cirrhosis, kidney disease, thyroid disease, and cancer in 2002. Analysis was conducted for 505 subjects with newly diagnosed simple renal cyst and 2,744 subjects without renal cyst in 2010. The simple renal cyst group was compared to a control group without renal cyst. RESULTS: Among 3,249 subjects, simple renal cyst and hypertension were newly diagnosed in 505 subjects and 503 subjects. The subjects who had simple renal cysts had significantly higher hypertension incidence (odds ratio [OR], 1.53; 95% confidence interval [CI], 1.20 to 1.94). Significant hypertension incidence was observed especially when the subjects had cysts located on both kidneys (OR, 3.48; 95% CI, 2.12 to 5.71), two (OR, 3.08; 95% CI, 1.84 to 5.15) or more cysts (OR, 3.12; 95% CI, 1.38 to 7.04), and larger cysts more than 1 cm in diameter (OR, 1.55; 95% CI, 1.16 to 2.07). CONCLUSION: The presence of simple renal cysts was significantly positively related to the incidence of hypertension. Bilateral distribution, two or more number, and larger size than 1 cm diameter were the characteristics of simple renal cyst related to hypertension.

Association of Apolipoprotein B/Apolipoprotein A1 Ratio and Coronary Artery Stenosis and Plaques Detected by Multi-Detector Computed Tomography in Healthy Population

Despite the noninvasiveness and accuracy of multidetector computed tomography (MDCT), its use as a routine screening tool for occult coronary atherosclerosis is unclear. We investigated whether the ratio of apolipoprotein B (apoB) to apolipoprotein A1 (apoA1), an indicator of the balance between atherogenic and atheroprotective cholesterol transport could predict occult coronary atherosclerosis detected by MDCT. We collected the data of 1,401 subjects (877 men and 524 women) who participated in a routine health screening examination of Asan Medical Center. Significant coronary artery stenosis defined as > 50% stenosis was detected in 114 subjects (8.1%). An increase in apoB/A1 quartiles was associated with increased percentages of subjects with significant coronary stenosis and noncalcified plaques (NCAP). After adjustment for confounding variables, each 0.1 increase in serum apoB/A1 was significantly associated with increased odds ratios (ORs) for coronary stenosis and NCAP of 1.23 and 1.18, respectively. The optimal apoB/A1 ratio cut off value for MDCT detection of significant coronary stenosis was 0.58, which had a sensitivity of 70.2% and a specificity of 48.2% (area under the curve, 0.61; 95% CI, 0.58-0.63, P < 0.001). Our results indicate that apoB/A1 ratio is a good indicator of occult coronary atherosclerosis detected by coronary MDCT.

Impact of HbA1c Criterion on the Detection of Subjects with Increased Risk for Diabetes among Health Check-Up Recipients in Korea

BACKGROUND: We performed the study to examine the impact of hemoglobin A1c (HbA1c) criterion on the screening of increased risk for diabetes among health check-up subjects in Korea. METHODS: We retrospectively analyzed clinical and laboratory data of 37,754 Korean adults (age, 20 to 89 years; 41% women) which were measured during regular health check-ups. After excluding subjects with previously diagnosed diabetes mellitus (n=1,812) and with overt anemia (n=318), 35,624 subjects (21,201 men and 14,423 women) were included in the analysis. RESULTS: Among the 35,624 subjects, 11,316 (31.8%) subjects were categorized as increased risk for diabetes (IRD) by fasting plasma glucose (FPG) criteria, 6,531 (18.1%) subjects by HbA1c criteria, and 13,556 (38.1%) subjects by combined criteria. Therefore, although HbA1c criteria alone identifies 42% [(11,316-6,531)/11,316] fewer subjects with IRD than does FPG criteria, about 20% [(13,556-11,316)/11,316] more subjects could be detected by including new HbA1c criteria in addition to FPG criteria. Among the 13,556 subjects with IRD, 7,025 (51.8%) met FPG criteria only, 2,240 (16.5%) met HbA1c criteria only, and 4,291 (31.7%) met both criteria. Among subjects with impaired fasting glucose, 65% were normal, 32% were IRD, and 3% were diabetes by HbA1c criterion. In receiver operating characteristic curve analysis, cutoff point of HbA1c with optimal sensitivity and specificity for identifying IRD was 5.4%. CONCLUSION: Although HbA1c criteria alone identifies fewer subjects with IRD than does FPG criteria, about 20% more could be detected by addition of HbA1c criteria. Further studies are needed to define optimal cutoff point of HbA1c and to establish screening and management guidelines for IRD.

A Case of Malignant Pheochromocytoma Presenting as Inverted Takotsubo-Like Cardiomyopathy

Takotsubo cardiomyopathy or stress induced cardiomyopathy is characterized by acute transient left ventricular apical ballooning without significant coronary artery disease. The pathophysiology of Takotsubo cardiomyopathy remains unclear, but it has been suggested that the stress related neurohumoral factors, especially catecholamines, play an important role. Recently, several reports have described an inverted Takotsubo cardiomyopathy, which is characterized by the dysfunction of the basal and mid-ventricular segments sparing the apex of the heart. In this report, we present a case of a 50-year-old female with a transient left ventricular dysfunction in an inverted Takotsubo pattern, that later was diagnosed as a malignant pheochromocytoma.

Response: Impact of HbA1c Criterion on the Detection of Subjects with Increased Risk for Diabetes among Health Check-Up Recipients in Korea (Diabetes Metab J 2012;36:151-6)

No abstract available.

Sequential Involvement of Distinct Portions of the Medial Prefrontal Cortex in Different Stages of Decision Making Using the Iowa Gambling Task

Functional magnetic resonance imaging (fMRI) was used to assess the temporal response of neural activation in healthy subjects while they performed the Iowa Gambling Test (IGT), which utilizes decisions involving ambiguity and risk. The IGT was divided into five blocks of 20 trials; analysis showed that activity in the medial prefrontal cortex (mPFC) moves gradually from the dorsal to the ventral mPFC over the course of the IGT. These findings suggest that cognitive division of the mPFC, including the dorsal portion of the anterior cingulated cortex (ACC), plays a major role in ambiguous decision making and that the aspect of the IGT corresponding to risky decision making is associated with significant activity within the corticolimbic network strongly implicated in emotion and reinforcement. Our results also suggest that decisions made under ambiguity and decisions made under risk situations can be further divided into sub-phases based on the neural network involved.

The Study of in Vivo Visual Pathway Tracing using Magnetic Magnanese Tracer / 의학물리

Purpose: To evaluate the tracing of optic nerve tract using manganese enhanced magnetic resonance imaging. Materials and Methods: After injecting 30 microliter of MnCl2 (1 mol) into the retina of female New Zealand white rabbit, the contrast enhancements at major anatomical structures of optic nerve tract were evaluated by high resolution T1-weighted images 12 hours, 24 hours, and 48 hours after MnCl2 injection using 3D FSPGR (Fast Spoiled Gradient Recalled echo) pulse sequence at 1.5 T clinical MR scanner with high performance gradient system. Also, for quantitative evaluation, the signal-to-noise ratios of circular ROI on anatomical locations were measured. Results: The major structures on the optic nerve tract were enhanced after injecting MnCl2. The structures, which showed enhancement, were right optic nerve, optic chiasm, left optic tract, left lateral geniculate nucleus, left superior colliculus. The structures on the contralateral optic pathway to the right retina were enhanced whereas the structures on the ipsilateral pathway did not show enhancement. Conclusion: The Mn transport through axonal pathway of optic nerve system was non-invasively observed after injecting MnCl2 at the retina, which is the end terminal of optic nerve system. This Mn transport seems to occur by voltage gated calcium (Ca2+) channel and in case of direct injection into the retina, the fast transport pathway of voltage gated calcium channel seems to be responsible for Mn transport.

Image Reconstruction of Eigenvalue of Diffusion Principal Axis Using Diffusion Tensor Imaging

PURPOSE: The objective of this work to construct eigenvalue maps that have information of magnitude of three primary diffusion directions using diffusion tensor images. MATERIALS AND METHODS: To construct eigenvalue maps, we used a 3.0T MRI scanner. We also compared the Moore-Penrose pseudo-inverse matrix method and the SVD (single value decomposition) method to calculate magnitude of three primary diffusion directions. Eigenvalue maps were constructed by calculating of magnitude of three primary diffusion directions. We did investigate the relationship between eigenvalue maps and fractional anisotropy map. RESULTS: Using Diffusion Tensor Images by diffusion tensor imaging sequence, we did construct eigenvalue maps of three primary diffusion directions. Comparison between eigenvalue maps and Fractional Anisotropy map shows what is difference of Fractional Anisotropy value in brain anatomy. Furthermore, through the simulation of variable eigenvalues, we confirmed changes of Fractional Anisotropy values by variable eigenvalues. And Fractional anisotropy was not determined by magnitude of each primary diffusion direction, but it was determined by combination of each primary diffusion direction. CONCLUSION: By construction of eigenvalue maps, we can confirm what is the reason of fractional anisotropy variation by measurement the magnitude of three primary diffusion directions on lesion of brain white matter, using eigenvalue maps and fractional anisotropy map.