Jin Ook Chung

Chonnam National University, Gwangju, Gwangju, South Korea

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Publications (19)11.12 Total impact

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    ABSTRACT: Bisphosphonates are potent antiresorptive drugs which have antifracture efficacy by reducing bone turnover rate and increasing bone mineral density. In addition to inhibiting osteoclast function, bisphosphonates have been reported to also promote survival of osteocyte and osteoblast via an anti-apoptotic effect, mediated by opening of hemi-gap junction channels formed by connexin43 (Cx43). In this study, we investigated the effect of risedronate, one amino-bisphosphonate, on osteoblast differentiation and Cx43 expression using the mesenchymal cell line C2C12. Risedronate dose-dependently increased the activity of osterix (OSE)-luciferase containing Runx2 response element with highest activity at 50 μM. The activity of osteocalcin (OC)- and bone sialoprotein (BSP)-luciferase reporters, markers of osteoblast differentiation, were also increased by risedronate. When risedronate and BMP2 were used in combination, alkaline phosphatase (ALP) activity increased to a larger extent than when BMP2 was used alone. Risedronate as well as the pro-osteogenic transcription factors, Runx2, Osterix or Dlx5, increased transcriptional activity of the Cx43 promoter in a dose-dependent manner. In the presence of Runx2 or Dlx5, risedronate had an additive effect on Cx43 promoter activity. Accordingly, risedronate increased protein expression of Cx43, Runx2, Osterix, and Dlx5. These results suggest that risedronate promotes osteoblastic differentiation and positively regulates Cx43 gene transcription.
    Biochemical and Biophysical Research Communications 01/2013; · 2.41 Impact Factor
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    ABSTRACT: Objective This study assessed factors associated with the quality of life (QoL) and investigated the influence of age in 401 Korean type 2 diabetic patients. Methods The QoL was assessed using the latest version of the Audit of Diabetes-Dependent Quality of Life (ADDQoL) instrument in order to evaluate the perceived impact of diabetes on 19 life domains. The Beck Depression Inventory (BDI) was used to measure depressive symptoms. Logistic regression analyses were performed to assess the associations between the factors and the ADDQoL scores in the lower quartile. The interaction terms of these factors with age strata were included to evaluate the distinctive associations across age, followed by a stratified analysis. Results According to a multivariate analysis, a positive association between depressive symptoms (BDI ≥16) and lower ADDQoL scores was consistently found across all ages. In the younger group (<60 years), insulin use (odds ratio: 4.45, 95% confidence interval: 1.29-15.33, p=0.018) and the presence of a family history of diabetes (OR: 0.23, 95% CI: 0.08-0.68, p=0.008) were independently associated with lower ADDQoL scores. However, in the older group (≥60 years), insulin use and a family history of diabetes were not significantly associated with lower ADDQoL scores. Conclusion The findings suggest that insulin use, depressive symptoms and a family history of diabetes can be associated with the QoL in Korean type 2 diabetic patients; however, the associations show different patterns of age dependency.
    Internal Medicine 01/2013; 52(2):179-85. · 0.97 Impact Factor
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    ABSTRACT: Many studies have demonstrated an association between hemoglobin levels and cardiovascular disease in diabetic patients. The aim of this study was to determine whether there is an association between hemoglobin concentrations and various clinical parameters, including metabolic factors, plasma C-peptide response after a meal tolerance test, and microvascular complications, in Korean patients with type 2 diabetes. In total, 337 male patients with type 2 diabetes were recruited. All subjects were subjected to a meal tolerance test and underwent assessment of hemoglobin levels, fasting and postprandial β-cell responsiveness, and microvascular complications. Patients with lower hemoglobin concentrations had a longer duration of diabetes, a lower body mass index, and lower concentrations of total cholesterol, triglycerides, and low-density lipoprotein cholesterol. They also had lower levels of postprandial C-peptide, Δ C-peptide, and postprandial β-cell responsiveness. They had a higher prevalence of retinopathy and nephropathy. In multivariate analyses, there was a significant association between nephropathy and hemoglobin concentration. Also, hemoglobin concentrations were independently associated with Δ C-peptide levels and postprandial β-cell responsiveness. Hemoglobin concentrations are associated with postprandial C-peptide responses and diabetic nephropathy in patients with type 2 diabetes.
    The Korean Journal of Internal Medicine 09/2012; 27(3):285-92.
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    ABSTRACT: We investigated the associations among body mass index (BMI), insulin resistance, and β-cell function in Korean patients newly presenting with type 2 diabetes. In total, 132 patients with new-onset type 2 diabetes mellitus were investigated. A standard 75-g oral glucose tolerance test was performed, and the indices of insulin secretion and insulin resistance were calculated. A higher BMI was associated with higher homeostasis model assessment values for insulin resistance (HOMA-IR), homeostasis model assessment of β-cell function (HOMA-β), and insulinogenic index as well as lower levels of insulin sensitivity index composite (ISI(comp)) and disposition index (DI). In multiple regression models, BMI had independent positive associations with HOMA-IR, ISI(comp), and HOMA-β and inverse associations with the DI. Our results showed that BMI had independent positive associations with indices of insulin resistance and an inverse association with β-cell function adjusted for insulin resistance in Korean patients newly presenting with type 2 diabetes.
    The Korean Journal of Internal Medicine 03/2012; 27(1):66-71.
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    Diabetes & metabolism journal 12/2011; 35(6):640-1.
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    ABSTRACT: Anticoagulation therapy with vitamin K antagonists such as warfarin is widely used to prevent and treat stroke in patients with chronic atrial fibrillation or mechanical heart valves. Because vitamin K is an essential factor for ggg-carboxylation of osteocalcin, vitamin K antagonists might cause bone loss. Although the association between warfarin use and bone metabolism is still controversial, several studies show that bone mineral density is decreased and fracture risk is increased with warfarin therapy. Meanwhile, attenuation of gap junctional communication (GJC) by warfarin is reported in rat liver epithelial cells. However, the effect of warfarin on osteoblasts, in which GJC is important for osteoblastic differentiation, remains unknown. Here we investigated whether warfarin has an inhibitory effect on osteoblastic differentiation using an osteoblastic cell line (C2C12). Warfarin and 18-α-glycyrrhetinic acid (AGA), which is known as a nontoxic reversible GJC inhibitor, had the same effect on osteoblastic differentiation. Warfarin and AGA inhibited the bone morphogenetic protein (BMP)2-induced mRNA levels of alkaline phosphatase (ALP), collagen I α1, osteocalcin (OC) and osterix, which are specific markers for osteoblastic differentiation, in a dose-dependent manner. Moreover, the activities of OC- and ALP-luciferase reporters, which are induced by BMP2, and the transcriptional activity of Runx2 on OC and ALP promoters were inhibited by warfarin and AGA. The amount and activity of ALP induced by BMP2 were also decreased by warfarin and AGA. These results suggest that warfarin and AGA, a GJC inhibitor, have an inhibitory effect on osteoblastic differentiation.
    Archives of Pharmacal Research 08/2011; 34(8):1381-7. · 1.54 Impact Factor
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    ABSTRACT: Diabetes mellitus is a major independent risk factor for cardiovascular disease (CVD), but high cardiovascular risk in diabetes mellitus patients is not completely explained by clustering traditional risk factors. Recently, associations between diabetic polyneuropathy (DPN) and macrovasculopathy have been suggested. We aimed to assess associations between DPN and cardiovascular complications in type 2 diabetic patients. Microvascular and cardiovascular complications were evaluated in 1,041 type 2 diabetic patients. In patients with DPN, the age, prevalence of hypertension, diabetes duration, systolic blood pressure, pulse pressure, and hemoglobin glycation (HbA1c) levels were significantly higher, while the high density lipoprotein cholesterol (HDL-C) levels were lower than in those without DPN. The prevalence of CVD was higher in patients with DPN. In multivariate analysis, DPN was independently associated with CVD (odds ratio, 1.801; 95% confidence interval, 1.009 to 3.214). Our results showed that DPN was associated with a high prevalence of cardiovascular disease in type 2 diabetic patients, but further studies are needed to investigate the causative nature of associations between DPN and CVD.
    Diabetes & metabolism journal 08/2011; 35(4):390-6.
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    ABSTRACT: We describe a rare case of transient thyrotoxicosis secondary to painless thyroiditis accompanied by panhypopituitarism caused by ruptured Rathke's cleft cyst. A 32-year-old man presented with vomiting and diarrhea. Laboratory data showed that he had transient hypercalcemia, primary thyrotoxicosis due to painless thyroiditis and panhypopituitarism. The sellar magnetic resonance imaging showed cystic macroadenoma. He underwent surgical exploration. Histological examination showed a ruptured Rathke's cleft cyst. Our case suggests that, although rare, it is important to recognize the possibility of coexistence of hypopituitarism in patients with primary thyrotoxicosis.
    Internal Medicine 01/2011; 50(24):2997-3001. · 0.97 Impact Factor
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    ABSTRACT: Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis, and it can be classified as either a functional or nonfunctional tumor. Affected patients usually present with abdominal pain or with symptoms related to the mass effect or hormonal activity of the tumor. Several cases of spontaneously ruptured nonfunctional adrenocortical carcinoma have been reported, but no case of a spontaneous rupture of functioning adrenocortical carcinoma has been described. We report a functioning adrenocortical carcinoma that spontaneously ruptured during a work-up.
    Yonsei medical journal 11/2010; 51(6):974-7. · 0.77 Impact Factor
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    ABSTRACT: Heparin and/or insulin stimulate lipoprotein lipase and are known to decrease serum triglyceride level. However, their efficacy in hypertriglyceridemia-induced acute pancreatitis in nondiabetic patients is not well documented. We report a case of hypertriglyceridemia-induced pancreatitis in 43-year-old nondiabetic woman in whom treatment with insulin was accompanied by reduction in serum triglyceride level and the resolution of pancreatitis. She presented to the emergency department with abdominal pain and biochemical evidence of acute pancreatitis. Her medical history was unremarkable. There was no history of alcohol consumption, and biliary imaging was not remarkable. Subsequent laboratory investigation revealed marked hypertriglyceridemia (1,951 mg/dL), impaired fasting glucose, and normal HbAlc level. The Ransons score and APATCH II score were 1 and 4. Abdominal CT showed diffuse enlargement of pancreas, peripancreatic fat infiltration, and multiple fluid collections around the pancreas. We treated the patient with the infusion of 5% dextrose and 1.5 unit/hr regular insulin to reduce serum triglyceride level. The level of serum triglyceride was decreased to 305 mg/dL on day 5. During the remainder of hospitalization, her clinical symptoms and laboratory values gradually improved.
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 06/2010; 55(6):399-403.
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    ABSTRACT: To characterize ultrasonographic findings in papillary thyroid carcinoma (PTC) combined with Graves' disease. Medical records and ultrasonographic findings of 1,013 patients with Graves' disease and 3,380 patients without Graves' disease were analyzed retrospectively. A diagnosis of PTC was based on a pathologic examination. The frequency of hypoechogenicity was lower in patients with PTC and Graves' disease than in patients with PTC alone (p < 0.05). The frequency of perinodular blood flow in patients with PTC and Graves' disease was significantly higher than in those with PTC alone (p < 0.05). PTC combined with Graves' disease was characterized by more ill-defined borders and less frequency of overall calcification, punctate calcification, and heterogeneous echogenicity, although the difference was not statistically significant. Our results suggest that patients with Graves' disease more frequently have atypical PTC findings on ultrasonography.
    The Korean Journal of Internal Medicine 03/2010; 25(1):71-6.
  • Endocrinology and Metabolism. 01/2010; 25(2).
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    ABSTRACT: Type 2 diabetes is characterized by progressive β-cell dysfunction. Family history of type 2 diabetes has been known to be associated with an increased risk for the development of the disease. However, few studies have evaluated the effects of family history of diabetes on residual β-cell function in type 2 diabetic patients. We investigated associations among family histories, clinical characteristics and plasma C-peptide levels in type 2 diabetic patients. A total of 1,350 patients with type 2 diabetes were recruited. The patients with a family history of type 2 diabetes had younger age at onset of diabetes, longer diabetes duration, higher LDL-cholesterol, and lower fasting C-peptide levels than the patients without family history. When divided according to the tertiles of diabetes duration, patients with a family history of type 2 diabetes had more decreased concentrations of fasting C-peptide as duration of diabetes increased, but patients without a family history did not. Multiple regression models were used to determine the association between fasting plasma C-peptide levels and a family history of type 2 diabetes mellitus. With adjustments for age and sex, glycated hemoglobin (HbA(1C)), fasting plasma glucose, free fatty acids, body mass index and diabetes mellitus (DM) duration, there was a significant association (P < 0.01). Our results showed that a family history of diabetes was significantly associated with the progressive decline of fasting plasma C-peptide levels in Korean type 2 diabetes mellitus.
    Endocrine Journal 01/2010; 57(10):931-8. · 2.23 Impact Factor
  • Journal of Korean Endocrine Society 01/2009; 24(3).
  • Korean Diabetes Journal 01/2009; 33(2).
  • Journal of Korean Endocrine Society 01/2009; 24(3).
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    ABSTRACT: An insulinoma is characterized by endogenous hyperinsulinemia and hypoglycemia. However, it has been reported that insulinomas with normal levels of plasma insulin and a normal insulin to glucose ratio occur in patients with hypoglycemia. Although overproduction of Insulin-like growth factor II (IGF-II) by non-islet cell tumors such as large mesenchymal tumors, can cause hypoglycemia, no cases of circulating plasma IGF-II from an islet cell tumor contributing to hypoglycemia have been reported. We report here a rare case of a pancreatic islet tumor in a patient with hypoglycemia that was associated with increased plasma IGF-II, which returned to normal after tumor resection.
    Endocrine Journal 08/2008; 55(3):607-12. · 2.23 Impact Factor
  • Journal of Korean Endocrine Society 01/2008; 23(3).
  • Journal of Korean Endocrine Society 01/2007; 22(4).