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3.  Natural Course of Cytologically Benign Thyroid Nodules: Observation of Ultrasonographic Changes 
Endocrinology and Metabolism  2013;28(2):110-118.
The natural course of cytologically benign thyroid nodules remains unclear. The aim of this study was to evaluate whether ultrasonographic (US) changes are associated with changes in nodule volume during follow-up.
We retrospectively reviewed over 4 years of clinical records of patients with benign thyroid nodules as confirmed by fine needle aspiration (FNA). In total, 186 patients with 202 benign thyroid nodules were included for study. We assessed for changes in nodule volume and examined the cystic portion of the nodule as well as four US features (echogenicity, margin, calcification pattern, and shape).
During follow-up (mean, 21.7±10.7 months) and using 50% as a cutoff value, nodule volumes increased in 11.8%, exhibited no change in 79.9%, and decreased in 8.3% of patients. Proportion of nodules demonstrating at least one US change was 20.8% (42/202). The most common US changes (in descending order of frequency) were cystic change, margin change, and calcification pattern change. Nodule shape and echogenicity rarely changed. Increased nodule volume was not significantly associated with any US features or with the number of FNAs but was associated with younger age at time of diagnosis.
Although a portion of thyroid nodules confirmed as benign showed US changes or volume changes during the follow-up period, these findings may only represent the natural course of benign nodules. Frequent follow-up with US might be needed for only a small number of cases with suspicious US findings.
PMCID: PMC3811716  PMID: 24396664
Thyroid nodule; Neoplasms; Ultrasonography; Growth; Tumor burden
4.  Exercise Treadmill Test in Detecting Asymptomatic Coronary Artery Disease in Type 2 Diabetes Mellitus 
Diabetes & Metabolism Journal  2011;35(1):34-40.
The present study was designed to develop criteria for screening patients with type 2 diabetes mellitus (T2DM) for asymptomatic coronary artery disease (CAD).
A total of 213 patients with T2DM without typical angina or chest pain were studied between 2002 and 2007. We also evaluated 53 patients with T2DM who had reported chest discomfort using an exercise treadmill test (ETT).
Thirty-one of the 213 asymptomatic patients had positive ETT results. We performed coronary angiography on 23 of the 31 patients with a positive ETT and found that 11 of them had significant coronary stenosis. The main differences between the patients with significant stenosis and those with a negative ETT were age (63.1±9.4 vs. 53.7±10.1 years, P=0.008) and duration of diabetes (16.0±7.5 vs. 5.5±5.7 years, P<0.001). The positive predictive value (PPV) of the ETT was calculated to be 47.8%. The PPV of the ETT increased to 87.5% in elderly patients (≥60 years) with a long duration of diabetes (≥10 years). The latter value is similar to that of patients with T2DM who presented with chest discomfort or exertional dyspnea. The PPV of the ETT in symptomatic patients was 76.9%.
In the interest of cost-effectiveness, screening for asymptomatic CAD could be limited to elderly patients with a duration of diabetes ≥10 years.
PMCID: PMC3080575  PMID: 21537411
Diabetes mellitus; Duration of diabetes; Exercise treadmill test; Silent myocardial ischemia
5.  Identification of Intermediate- to High-Risk Papillary Thyroid Carcinoma Patients Who May Be Safely Managed without the Performance of Delayed Stimulated Thyroglobulin Measurements following Total Thyroidectomy and Radioactive Iodine Therapy 
Background. The measurement of stimulated thyroglobulin (sTg) after total thyroidectomy and remnant radioactive iodine (RAI) ablation is the gold standard for monitoring disease status in patients with papillary thyroid carcinomas (PTCs). The aim of this study was to determine whether sTg measurement during follow-up can be avoided in intermediate- and high-risk PTC patients. Methods. A total of 346 patients with PTCs with an intermediate or high risk of recurrence were analysed. All of the patients underwent total thyroidectomy as well as remnant RAI ablation and sTg measurements. Preoperative and postoperative parameters were included in the analysis. Results. Among the preoperative parameters, age below 45 years and preoperative Tg above 19.4 ng/mL were significant risk factors for predicting detectable sTg during follow-up. Among the postoperative parameters, thyroid capsular invasion, lymph node metastasis, and ablative Tg above 2.9 ng/mL were independently correlated with a detectable sTg range. The combination of ablative Tg less than 2.9 ng/mL with pre- and postoperative independent risk factors for detectable sTg increased the negative predictive value for detectable sTg up to 98.5%. Conclusions. Based on pre- and postoperative parameters, a substantial proportion of patients with PTCs in the intermediate- and high-risk classes could avoid aggressive follow-up measures.
PMCID: PMC4306371  PMID: 25649811
6.  Effects of bariatric surgery on metabolic and nutritional parameters in severely obese Korean patients with type 2 diabetes: A prospective 2‐year follow up 
Little is known about the long‐term effects of Roux‐en‐Y gastric bypass (RYGB) in severely obese Asian individuals.
Methods and Materials
A total of 33 severely obese patients with type 2 diabetes underwent RYGB. All patients were followed up for 2 years. Visceral and abdominal subcutaneous fat areas were assessed using computed tomography (CT) before, and 12 and 24 months after RYGB. The muscle attenuation (MA) of paraspinous muscles observed by CT were used as indices of intramuscular fat.
The mean percentage weight loss was 22.2 ± 5.3% at 12 months, and 21.3 ± 5.1% at 24 months after surgery. Compared with the baseline values, the visceral fat area was 53.6 ± 17.1% lower 24 months after surgery, and the abdominal subcutaneous fat area was 32.7 ± 16.1% lower 24 months after surgery. The MA increased from 48.7 ± 10.0 at baseline to 52.2 ± 8.9 (P = 0.009) 12 months after surgery. The MA after the first 12 months maintained changes until 24 months. Triglycerides and free fatty acids were reduced after surgery, whereas the high‐density lipoprotein cholesterol levels were increased significantly after surgery. At the last follow‐up visit, 18 patients (55%) had diabetes remission. The percentage of iron and vitamin D deficiency was 30% and 52%, respectively.
We found that patients subjected to RYGB had significant sustained reductions in visceral and intramuscular fat. There were durable improvements in the cardiometabolic abnormalities without any significant comorbidities. However, there were mild nutritional deficiencies in these patients despite daily supplementation with multivitamins and minerals.
PMCID: PMC4023587  PMID: 24843764
Bariatric surgery; Visceral fat; Intramuscular fat
7.  Changes in Serum Levels of Bone Morphogenic Protein 4 and Inflammatory Cytokines after Bariatric Surgery in Severely Obese Korean Patients with Type 2 Diabetes 
Serum bone morphogenic protein- (BMP-) 4 levels are associated with human adiposity. The aim of this study was to investigate changes in serum levels of BMP-4 and inflammatory cytokines after Roux-en-Y gastric bypass (RYGB). Fifty-seven patients with type 2 diabetes underwent RYGB. Serum levels of BMP-4 and various inflammatory markers, including high-sensitivity C-reactive protein (hsCRP), free fatty acids (FFAs), and plasminogen activator inhibitor- (PAI-) 1, were measured before and 12 months after RYGB. Remission was defined as glycated hemoglobin <6.5% for at least 1 year in the absence of medications. Levels of PAI-1, hsCRP, and FFAs were significantly decreased at 1 year after RYGB. BMP-4 levels were also significantly lower at 1 year after RYGB than at baseline (P = 0.024). Of the 57 patients, 40 (70%) had diabetes remission at 1 year after surgery (remission group). Compared with patients in the nonremission group, patients in the remission group had lower PAI-1 levels and smaller visceral fat areas at baseline. There was a difference in the change in the BMP-4 level according to remission status. Our data demonstrate a significant beneficial effect of bariatric surgery on established cardiovascular risk factors and a reduction in chronic nonspecific inflammation after surgery.
PMCID: PMC3792548  PMID: 24170999
8.  Influence of Visceral Adiposity on Cardiovascular Autonomic Neuropathy in Patients with Type 2 Diabetes Mellitus 
Diabetes & Metabolism Journal  2012;36(4):285-292.
The aim of this study was to investigate the influences of visceral adiposity on cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus.
Two hundred eleven patients with type 2 diabetes participated in this study. Anthropometric and metabolic parameters were measured, and the visceral fat area was assessed using computed tomography. CAN was diagnosed using a cardiovascular reflex test. We analyzed the correlation between the visceral fat area and each parameter in this test.
The mean age, body mass index (BMI), and duration of diabetes of the study population were 60±14 years (mean±standard deviation), 25.1±4.2 kg/m2, and 12.3±8.9 years, respectively. The visceral fat area showed positive correlations with age, BMI, waist circumference, and subcutaneous fat area. There was no statistically significant difference in the cardiovascular reflex test outcome between genders. Univariate linear regression analysis showed that an increased visceral fat area diminished good heart rate response to a Valsalva maneuver (R2=4.9%, P=0.013 in an unadjusted model), but only in women. This statistical association was preserved after adjusting for age and BMI (R2=9.8%, P=0.0072).
The results of this study suggest that visceral adiposity contributes to an autonomic imbalance to some degree, as demonstrated by the impaired cardiovascular reflex test among women with type 2 diabetes.
PMCID: PMC3428417  PMID: 22950060
Cardiovascular autonomic neuropathy; Diabetes mellitus, type 2; Intra-abdominal fat; Obesity
9.  Relationship between Vitamin D, Parathyroid Hormone, and Bone Mineral Density in Elderly Koreans 
Journal of Korean Medical Science  2012;27(6):636-643.
There is controversy regarding definition of vitamin D inadequacy. We analyzed threshold 25-hydroxyvitamin D (25[OH]D) below which intact parathyroid hormone (iPTH) increases, and examined age- and sex-specific changes of 25(OH)D and iPTH, and association of 25(OH)D and iPTH with bone mineral density (BMD) in elderly Koreans. Anthropometric parameters, serum 25(OH)D and iPTH, lumbar spine and femur BMD by dual-energy radiography absorptiometry (DXA) were measured in 441 men and 598 postmenopausal women. iPTH increased below serum 25(OH) of 36.7 ng/mL in men, but failed to reach plateau in women. Femur neck BMD above and below threshold differed when threshold 25(OH)D concentrations were set at 15-27.5 ng/mL in men, and 12.5-20 ng/mL in postmenopausal women. Vitamin D-inadequate individuals older than 75 yr had higher iPTH than those aged ≤ 65 yr. In winter, age-associated iPTH increase in women was steeper than in summer. In conclusion, vitamin D inadequacy threshold cannot be estimated based on iPTH alone, and but other factors concerning bone health should also be considered. Older people seemingly need higher 25(OH)D levels to offset age-associated hyperparathyroidism. Elderly vitamin D-inadequate women in the winter are most vulnerable to age-associated hyperparathyroidism.
PMCID: PMC3369450  PMID: 22690095
Vitamin D; Intact Parathyroid Hormone; Bone Density; Age; Sex
10.  Effects of Thyroid Hormone on A1C and Glycated Albumin Levels in Nondiabetic Subjects With Overt Hypothyroidism 
Diabetes Care  2010;33(12):2546-2548.
We aimed to determine the effects of thyroid hormone on A1C and glycated albumin (GA) in nondiabetic patients with overt hypothyroidism.
A1C levels were measured in 45 nondiabetic patients with overt hypothyroidism and 180 euthyroid control subjects. A1C, GA, fasting blood glucose (FBG), 1,5-anhydroglucitol, and erythrocyte indexes were determined in 30 nondiabetic patients with overt hypothyroidism before and after thyroid hormone replacement.
A1C levels were higher in patients with hypothyroidism compared with control subjects. A1C levels were decreased by thyroid hormone replacement. Thyroid hormone replacement increased serum erythropoietin, reticulocyte count, and mean corpuscular hemoglobin (MCH). The change in A1C level was significantly correlated with the change in reticulocyte count or MCH. Thyroid hormone replacement decreased serum levels of albumin and GA. However, FBG and 1,5-anhydroglucitol levels were not altered.
Levels of A1C and GA are spuriously high in nondiabetic patients with overt hypothyroidism.
PMCID: PMC2992186  PMID: 20823345
11.  T Lymphocytes Amplify the Anabolic Activity of Parathyroid Hormone Through Wnt10b Signaling 
Cell metabolism  2009;10(3):229-240.
Intermittent administration of parathyroid hormone (iPTH) is used to treat osteoporosis as it improves bone architecture and strength, but the underlying cellular and molecular mechanisms are unclear. Here we show that iPTH increases the production of Wnt10b by bone marrow CD8+ T cells, and induces these lymphocytes to activate canonical Wnt-signaling in pre-osteoblasts. Accordingly, in responses to iPTH, T cell null mice display diminished Wnt signaling in pre-osteoblasts and blunted osteoblastic commitment, proliferation, differentiation and lifespan which result in decreased trabecular bone anabolism and no increase in strength. Demonstrating the specific role of lymphocytic Wnt10b, iPTH has no anabolic activity in mice lacking T cell produced Wnt10b. Therefore, T cell mediated activation of Wnt signaling in osteoblastic cells plays a key permissive role in the mechanism by which iPTH increases bone strength, suggesting that T cell osteoblast cross-talk pathways may provide pharmacological targets for bone anabolism.
PMCID: PMC2751855  PMID: 19723499
12.  Long-Term Effects of Rosiglitazone on the Progressive Decline in Renal Function in Patients With Type 2 Diabetes 
Thiazolidinediones reduce urinary albumin excretion and may prevent the development of renal injury. We evaluated the long-term effects of rosiglitazone on the progression of renal dysfunction in patients with type 2 diabetes mellitus.
We enrolled patients with type 2 diabetes mellitus who initially had normal or mildly impaired renal function, defined as an estimated glomerular filtration rate (eGFR) of 60-120 mL/min per 1.73 m2, and normoalbuminuria. Patients were divided into two groups according to their use of rosiglitazone during 3 years of follow-up: those treated with rosiglitazone (rosiglitazone group, n=52) and those treated without rosiglitazone (control group, n=85). Progression of renal dysfunction was defined as a decrease in eGFR of ≥9 mL/min per 1.73 m2 after 3 years.
A greater difference was observed in the decrease in eGFR between the rosiglitazone and control groups after 3 years (3.8±9.9 vs. 12.6±10.5 mL/min per 1.73 m2, p<0.001). Seventeen of 52 (32.7%) patients in the rosiglitazone group and 53 of 85 (62.3%) patients in the control group showed progression of renal dysfunction (p=0.001). The progressors had a longer duration of diabetes (6.7±5.9 vs. 3.9±4.1 years, p=0.002), higher HbA1c levels (7.4±1.8 vs. 6.8±1.3%, p=0.023), and less frequent use of rosiglitazone (24.2 vs. 52.2%, p<0.001) compared to non-progressors. Multiple logistic regression analysis revealed that the use of rosiglitazone was a significant and independent predictor of the progression of renal dysfunction.
This study suggests that rosiglitazone theatment slows the progressive deterioration of renal function in patients with type 2 diabetes.
PMCID: PMC2732782  PMID: 19721859
Diabetic nephropathies; Rosiglitazone; Renal insufficiency
13.  The Effect of Simvastatin on the Proliferation and Differentiation of Human Bone Marrow Stromal Cells 
Journal of Korean Medical Science  2005;20(3):438-444.
Statins have been postulated to affect the bone metabolism. Recent experimental and epidemiologic studies have suggested that statins may also have bone protective effects. This study assessed the effects of simvastatin on the proliferation and differentiation of human bone marrow stromal cells (BMSCs) in an ex vivo culture. The bone marrow was obtained from healthy donors. Mononuclear cells were isolated and cultured to osteoblastic lineage. In the primary culture, 10-6 M simvastatin diminished the mean size of the colony forming units-fibroblastic (CFU-Fs) and enhanced matrix calcification. At near confluence, the cells were sub-cultured. Thereafter, the alkaline phosphatase (ALP) activities of each group were measured by the time course of the secondary culture. Simvastatin increased the ALP activity in a dose dependent manner, and this stimulatory effect was more evident during the early period of culture. A 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay was performed during the secondary culture in order to estimate the effect of simvastatin on the proliferation of human BMSCs. When compared to the control group, simvastatin significantly decreased the proliferation of cells of each culture well. 10-6 M of simvastatin also significantly enhanced the osteocalcin mRNA expression level. This study shows that simvastatin has a stimulatory effect on bone formation through osteoblastic differentiation, and has an inhibitory effect on the proliferative potential of human BMSCs
PMCID: PMC2782200  PMID: 15953866
Simvastatin; Osteoblasts; Cell Proliferation; Cell Differentiation; Bone Marrow Cells; Stromal Cells
14.  The skeletal site-differential changes in bone mineral density following bone marrow transplantation: 3-year prospective study. 
Journal of Korean Medical Science  2002;17(6):749-754.
Loss of bone mass is usually detected after bone marrow transplantation (BMT) during the early post-transplant period. However, little is known about the long-term effects of BMT on bone metabolism. We have prospectively investigated 11 patients undergoing BMT. Bone mineral density (BMD) was measured before BMT, and 1, 2, and 3 yr after BMT. Serum markers of bone turnover were serially measured before BMT and 1, 2, 3, 4, and 12 weeks, 6 months, and 1 yr after BMT. The mean change in the lumbar spine (L2-4) BMD, calculated as the percent change from the baseline to the level at 1, 2, and 3 yr was -4.7% (NS), -1.1% (NS), and +6.4% (p<0.05), respectively. The mean change in the total proximal femur BMD from the baseline to the level at 1, 2, and 3 yr was -8.5% (p<0.01), -8.7% (p<0.05) and -5.6% (p<0.05), respectively. In summary, there was little decline in lumbar BMD at 1 yr following BMT and gradual recovery until 3 yr. In contrast, femoral BMD decreased much more than the lumbar area at 1 yr and did not recover until 3 yr. The mechanism of skeletal site-selective differences in the changes of BMD needs to be elucidated.
PMCID: PMC3054966  PMID: 12482996
15.  Circulating IL-8 and IL-10 in euthyroid sick syndromes following bone marrow transplantation. 
Journal of Korean Medical Science  2002;17(6):755-760.
It is generally agreed that euthyroid sick syndromes (ESS) are associated with an increased production of cytokines. However, there has been scarce data on the relationship thyroid hormone changes and cytokines among the patients undergoing bone marrow transplantation (BMT). Because interleukin-8 (IL-8) has been identified as a potent proinflammatory and interleukin-10 (IL-10) as an antiinflammatory cytokine, we studied the relation between thyroid hormone parameters and these cytokines following BMT. We studied 80 patients undergoing allogeneic BMT. Serum T3 decreased to nadir at post-BMT 3 weeks. Serum T4 was the lowest at the post-BMT 3 months. Serum TSH sharply decreased to nadir at 1 week and gradually recovered. Serum free T4 significantly increased during 3 weeks and then returned to basal level. Mean levels of serum IL-8 significantly increased at 1 week after BMT. Mean levels of serum IL-10 significantly increased until 4 weeks after BMT. No significant correlation was found between serum thyroid hormone parameters and cytokines (IL-8, IL-10) after adjusting steroid doses during the entire study period. In conclusion, ESS developed frequently following allogeneic BMT and cytokine levels were increased in post-BMT patients. However, no significant correlation was found between serum thyroid hormone parameters and these cytokines.
PMCID: PMC3054971  PMID: 12482997

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