Seok Hong Lee

Receptor activator of nuclear factor-κB ligand is a novel inducer of myocardial inflammation

AIMS Although increased levels of myocardial receptor activator of nuclear factor (NF)-κB ligand (RANKL) have been reported in heart failure, the role of this pathway in mediating activation of inflammatory pathways during myocardial remodelling is less well understood. This study sought to determine the role of myocardial RANKL in regulating cytokine expression. METHODS AND RESULTS A marked increase in RANKL expression occurred as early as 6h following transverse aortic constriction (TAC) in mouse hearts and persisted at 3 and 17 days. An increase in tumour necrosis factor-α (TNF-α), interleukin (IL)-1α, and IL-1β was observed in the hypertrophied hearts only at 3 or 17 days after TAC. Treatment with losartan significantly attenuated TAC-induced cardiac hypertrophy, in parallel with decreased expression of RANKL, TNF-α, IL-1α, and IL-1β. Furthermore, injection of a RANKL-neutralizing monoclonal antibody attenuated RANKL-induced cytokine expression. RANKL stimulated expression of TNF-α, IL-1α, and IL-1β in neonatal rat cardiomyocytes via activation of NF-κB. RANKL-induced NF-κB activation and expression of these cytokines were both attenuated when RANK, receptor for RANKL, or TRAF2 or TRAF6, adaptors for RANK, was silenced by siRNA. Furthermore, inhibitors of phospholipase C (PLC), protein kinase C (PKC), and inhibitor of κB kinase also significantly inhibited RANKL-induced cellular activities, but inhibitors of phosphatidylinositol 3-kinase, extracellular signal-regulated kinase, or p38 mitogen-activated protein kinase were without effect. CONCLUSION Our data demonstrate for the first time that the pressure-overloaded myocardium generates RANKL, which induces TNF-α, IL-1α, and IL-1β production via a RANK-TRAF2/TRAF6-PLC-PKC-NF-κB-mediated autocrine mechanism.

Reliability and validity of a self-reported measure of medication adherence in patients with type 2 diabetes mellitus in Korea

Objective This study examined the psychometric properties of the Korean version of the eight-item Morisky Medication Adherence Scale (MMAS-8) to measure adherence to diabetes medication in patients with type 2 diabetes mellitus. Methods The English version of the MMAS-8 was translated into Korean and administered to patient with type 2 diabetes mellitus via face-to-face interviews, conducted by an independent interviewer. Patient characteristics and glycosylated haemoglobin (HbA1c) levels were assessed at the same clinic visit. A proportion of patients was randomly selected for 2-week test-retest reliability via telephone interviews. Convergent validity of the MMAS-8 against a four-item MMAS, correlations with HbA1c levels and construct validity of the MMAS-8 were evaluated. Results In total, 317 patients were included; 70 completed the 2-week test–retest interview. Internal consistency reliability was moderate and test–retest reliability of the MMAS-8 was excellent, although a ceiling effect was detected. Good convergent validity was shown by the high correlation of the new scale scores with the original MMAS-4. A significant association was found between MMAS-8 scores and HbA1c levels. Using glycaemic control as a gold standard, sensitivity was 74.1% and specificity was 38.3%. Explanatory factor analysis identified three dimensions of the scale. Conclusions In light of acceptable reliability and validity, the MMAS-8 is a simple and quick method for the assessment of medication adherence among patient with type 2 diabetes mellitus, in a busy clinic setting.

IGF-1 receptor deficiency in thyrocytes impairs thyroid hormone secretion and completely inhibits TSH-stimulated goiter

Although thyroid‐stimulating hormone (TSH) is known to be a major regulator of thyroid hormone biosynthesis and thyroid growth, insulin‐like growth factor 1 (IGF‐1) is required for mediating thyrocyte growth in concert with TSH in vitro. We generated mice with thyrocyte‐selective ablation of IGF‐1 receptor (TIGF1RKO) to explore the role of IGF‐1 receptor signaling on thyroid function and growth. In 5‐wk‐old TIGF1RKO mice, serum thyroxine (T4) concentrations were decreased by 30% in concert with a 43% down‐regulation of the monocarboxylate transporter 8 (MCT8), which is involved in T4 secretion. Despite a 3.5‐fold increase in circulating concentrations of TSH, thyroid architecture and size were normal. Furthermore, thyrocyte area was increased by 40% in WT thyroids after 10 d TSH injection, but this effect was absent in TSH‐injected TIGF1RKO mice. WT mice treated with methimazole and sodium perchlorate for 2 or 6 wk exhibited pronounced goiter development (2.0 and 5.4‐fold, respectively), but in TIGF1RKO mice, goiter development was completely abrogated. These data reveal an essential role for IGF‐1 receptor signaling in the regulation of thyroid function and TSH‐stimulated goitrogenesis.—Ock, S., Ahn, J., Lee, S. H., Kang, H., Offermanns, S., Ahn, H. Y., Jo, Y.S., Shong, M., Cho, B. Y., Jo, D., Abel, E. D., Lee, T. J., Park, W. J., Lee, I.‐K., Kim, J. IGF‐1 receptor deficiency in thyrocytes impairs thyroid hormone secretion and completely inhibits TSH‐stimulated goiter. FASEB J. 27, 4899–4908 (2013). www.fasebj.org

Cardiomyocyte Specific Deletion of Crif1 Causes Mitochondrial Cardiomyopathy in Mice

Mitochondria are key organelles dedicated to energy production. Crif1, which interacts with the large subunit of the mitochondrial ribosome, is indispensable for the mitochondrial translation and membrane insertion of respiratory subunits. To explore the physiological function of Crif1 in the heart, Crif1f/f mice were crossed with Myh6-cre/Esr1 transgenic mice, which harbor cardiomyocyte-specific Cre activity in a tamoxifen-dependent manner. The tamoxifen injections were given at six weeks postnatal, and the mutant mice survived only five months due to hypertrophic heart failure. In the mutant cardiac muscles, mitochondrial mass dramatically increased, while the inner structure was altered with lack of cristae. Mutant cardiac muscles showed decreased rates of oxygen consumption and ATP production, suggesting that Crif1 plays a critical role in the maintenance of both mitochondrial structure and respiration in cardiac muscles.

A Case of Teriparatide on Pregnancy-Induced Osteoporosis

Pregnancy-induced osteoporosis is a rare disorder characterized by fragility fracture and low bone mineral density (BMD) during or shortly after pregnancy, and its etiology is still unclear. We experienced a case of a 39-year-old woman who suffered from lumbago 3 months after delivery. Biochemical evidence of increased bone resorption is observed without secondary causes of osteoporosis. Radiologic examination showed multiple compression fractures on her lumbar vertebrae. We report a case of patient with pregnancy-induced osteoporosis improved her clinical symptom, BMD and bone turnover marker after teriparatide therapy.

True euglycemic diabetic ketoacidosis in a person with type 2 diabetes and Duchenne muscular dystrophy

True euglycemic diabetic ketoacidosis is a rare complication of diabetes. We describe a case of diabetic ketoacidosis in a male with type 2 diabetes and Duchenne muscular dystrophy. He presented with normal plasma glucose as a consequence of starvation, reduced muscle mass and increased body fat.

Thyrocyte-specific deletion of insulin and IGF-1 receptors induces papillary thyroid carcinoma-like lesions through EGFR pathway activation: Insulin and IGF-1 receptors in thyroid cancer development

Insulin and insulin‐like growth factor (IGF)‐1 signaling in the thyroid are thought to be permissive for the coordinated regulation by thyroid‐stimulating hormone (TSH) of thyrocyte proliferation and hormone production. However, the integrated role of insulin receptor (IR) and IGF‐1 receptor (IGF‐1R) in thyroid development and function has not been explored. Here, we generated thyrocyte‐specific IR and IGF‐1R double knockout (DTIRKO) mice to precisely evaluate the coordinated functions of these receptors in the thyroid of neonates and adults. Neonatal DTIRKO mice displayed smaller thyroids, paralleling defective folliculogenesis associated with repression of the thyroid‐specific transcription factor Foxe1. By contrast, at postnatal day 14, absence of IR and IGF‐1R paradoxically induced thyrocyte proliferation, which was mediated by mTOR‐dependent signaling pathways. Furthermore, we found elevated production of TSH during the development of follicular hyperplasia at 8 weeks of age. By 50 weeks, all DTIRKO mice developed papillary thyroid carcinoma (PTC)‐like lesions that correlated with induction of the ErbB pathway. Taken together, these data define a critical role for IR and IGF‐1R in neonatal thyroid folliculogenesis. They also reveal an important reciprocal relationship between IR/IGF‐1R and TSH/ErbB signaling in the pathogenesis of thyroid follicular hyperplasia and, possibly, of papillary carcinoma.