The Effects of Glyburide on Apoptosis and Endoplasmic Reticulum Stress in INS-1 Cells in a Glucolipotoxic Condition

BACKGROUND: beta-cell death due to endoplasmic reticulum (ER) stress has been regarded as an important pathogenic component of type 2 diabetes. The possibility has been suggested that sulfonylurea, currently being used as one of the main oral hypoglycemic agents of type 2 diabetes, increases ER stress, which could lead to sulfonylurea failure. The authors of the present study examined ER stress of beta-cells in a glucolipotoxic condition using glyburide (GB) in an environment mimicking type 2 diabetes. METHODS: Apoptosis was induced by adding various concentrations of GB (0.001 to 200 microM) to a glucolipotoxic condition using 33 mM glucose, and the effects of varied concentrations of palmitate were evaluated via annexin V staining. The markers of ER stress and pro-apoptotic markers were assessed by Western blotting and semi-quantitative reverse transcription-polymerase chain reaction. Additionally, the anti-apoptotic markers were evaluated. RESULTS: Addition of any concentration of GB in 150 microM palmitate and 33 mM glucose did not increase apoptosis. The expression of phosphorylated eukaryotic initiation factor (eIF-2alpha) was increased and cleaved caspase 3 was decreased by adding GB to a glucolipotoxic condition. However, other ER stress-associated markers such as Bip-1, X-box binding protein-1, ATF-4 and C/EBP-homologous protein transcription factor and anti-apoptotic markers phosphor-p85 phosphatidylinositol 3-kinase and phosphorylation of Akt did not change significantly. CONCLUSION: GB did not show further deleterious effects on the degree of apoptosis or ER stress of INS-1 cells in a glucolipotoxic condition. Increased phosphorylation of eIF-2alpha may attenuate ER stress for adaptation to increased ER protein load.

The Effect of Glucose Fluctuation on Apoptosis and Function of INS-1 Pancreatic Beta Cells / 당뇨병

BACKGROUND: Blood glucose level continuously fluctuates within a certain range in the human body. In diabetes patients, the extent of such fluctuation is large, despite the strict control of blood glucose. Blood glucose fluctuation has been shown to mediate more adverse effects on vascular endothelial cells and diabetes complications than chronic hyperglycemia, which has been explained as due to oxidative stress. As few previous studies have reported the effects of chronic and intermittent hyperglycemia on the apoptosis and function of pancreatic beta cells, this study reported herein was performed to investigate such effects on these cells. METHODS: For chronic hyperglycemia, INS-1 cells were cultured for 5 days with changes of RPMI 1640 medium containing 33 mM glucose every 12 hours. For intermittent hyperglycemia, the medium containing 11 mM glucose was exchanged with the medium containing 33 mM glucose every 12 hours. Apoptosis was assessed by TUNEL assay Hoechst staining and cleaved caspase 3. Insulin secretory capacity was assessed, and the expression of Mn-SOD and Bcl-2 was measured by Western blotting. RESULTS: In comparison to the control group, INS-1 cells exposed to chronic hyperglycemia and intermittent hyperglycemia showed an increase in apoptosis. The apoptosis of INS-1 cells exposed to intermittent hyperglycemia increased significantly more than the apoptosis of INS-1 cells exposed to chronic hyperglycemia. In comparison to the control group, the insulin secretory capacity in the two hyperglycemic states was decreased, and more with intermittent hyperglycemia than with chronic hyperglycemia. The expression of Mn-SOD and Bcl-2 increased more with chronic hyperglycemia than with intermittent hyperglycemia. CONCLUSION: Intermittent hyperglycemia induced a higher degree of apoptosis and decreased the insulin secretory capacity more in pancreatic beta cells than chronic hyperglycemia. This activity may be mediated by the anti-oxidative enzyme Mn-SOD and the anti-apoptotic signal Bcl-2.

The Effect of Atorvastatin and Simvastatin on NIS Expression of the TPC-1 Cell under the Therapeutic Blood Concentrations

BACKGROUND: Although so many experimental trials have been done to improve the redifferentiation and responsiveness of radioiodide therapy, they have not yet yielded any satisfactory results. As statins inhibit both farnesylation and geranylgeranylation, they have been reported to have an antineoplastic and redifferentiation effect in experimental and clinical studies. In this study, we investigated the relationship between statins and the alteration of the NIS expression and, TPC-1 cell apotosis to evaluate the possibility of using statins as adjuvant therapeutic agents for papillary thyroid cancer. METHODS: We used the TPC-1 cell lines for our experiments. Cell viabilities were measured by CCK-8. The degrees of apoptosis and, the expressions of NIS mRNA and NIS protein were measured by flow cytometry, semi quantitative RT-PCR and Western blot assay. RESULTS: Increased levels of NIS mRNA and NIS protein were observed under therapeutic blood concentrations (concentrations of simvastatin: 20, 50, 80 nM, concentrations of atorvastatin: 50, 80,110 nM), but the dose-response relationship was only manifested within simvastatin. The TPC-1 cells showed a concentration dependent decrease of viability and an increase of apoptosis not under therapeutic blood concentrations, but under excessively high concentrations (after treatment with 10-50 microM of atorvastatin and with 1-10 microM of simvastatin). CONCLUSION: The results of this study show that effective therapeutic blood concentrations of simvastatin and atorvastatin can give a favorable effect on the NIS expression under effective therapeutic blood concentrations. Therefore, we demonstrated the possibility that simvastatin and atorvastatin might have an important role as adjuvant therapeutic agents to improve the responsiveness of radioiodide therapy for papillary thyroid cancer. Further studies are needed to clarify this issue.

A Case with Patent Ductus Arteriosus Complicated by Pulmonary Artery Endarteritis

Infective endarteritis in the pulmonary artery is unusual. However, congenital heart disease such as patent ductus arteriosus (PDA) could be a predisposing factor of infective endarteritis. We report a patient with PDA complicated by infective endarteritis and large pulmonary artery vegetation. After three weeks of antibiotic treatment, the patient underwent surgical closure of the PDA and removal of the vegetation.

A case of Gitelman's Syndrome with Chronic Hypotension and Normomagnesemia / 대한신장학회지

Gitelman's syndrome is a heritable renal disorder characterized by hypomagnesemia, hypokalemia and hypocalciuria. Interestingly, we have experienced one patient who had chronic hypotension, normal serum magnesium level, normal plasma ionized magnesium level, hypokalemia and hypocalciuria. Immunohistochemistry showed the absence of NCCT staining in renal tissues of the patient. We report the case of atypical Gitelman's syndrome with a brief review of related literature.

Comparison of oral N-acetylcysteine(NAC) and prehydration for preventing contrast-induced nephropathy in patients with renal dysfunction / 대한내과학회지

BACKGROUND: Contrast induced nephropathy (CIN) is an important cause of acute renal failure in patients with renal dysfunction. We investigated whether oral NAC alone was sufficient to prevent CIN to the same extent as hydration in patients with renal dysfunction, and whether these treatments resulted in diffierences in the urinary excretion of nitric oxide, a vasodilator. METHODS: A total of 27 patients with renal dysfunction, who underwent radiographic examination with nonionic and low osmolar contrast, were randomly assigned to receive either NAC (600 mg orally twice daily; N=11) or 0.45% saline hydration (1 mL/kg/Hr; N=16) 12 hours prior to and 12 hours after the contrast procedure. We measured serum creatinine (sCr), fractional excretion of sodium (FENa), creatinine clearance (CCr), and urinary nitrite before and after contrast administration. RESULTS: The mean volume of contrast used was similar in the two groups (100.9+/-54.8 mL vs 114.7+/-38 mL; p=0.43), as was baseline sCr in the two groups (2.31+/-1.59 mg/dL vs 2.18+/-1.41 mg/dL; p=0.98). Treatment did not significantly affect the incidence of CIN, with 18.2% and 12.5% in the NAC group and hydration group, respectively (p=1.0). The urinary nitrite/creatinine ratio (micro mol/mg) was 1.26+/-0.57 and 1.43+/-0.64 at baseline and 48 hours after contrast exposure in the NAC group, respectively, and 0.80+/-0.40 and 1.18+/-0.60 in the hydration group, respectively, which were not significantly different. FENa increased significantly after contrast exposure in the NAC group compared with hydration group (p=0.04) CONCLUSIONS: NAC alone may prevent CIN. When bolus hydration is contraindicated in patients with renal dysfunction, administration of NAC alone may be sufficient.