Advanced Glycation End-Products Induce Apoptosis of Vascular Smooth Muscle Cells: A Mechanism for Vascular Calcification.

Vascular calcification, especially medial artery calcification, is associated with cardiovascular death in patients with diabetes mellitus and chronic kidney disease (CKD). To determine the underlying mechanism of vascular calcification, we have demonstrated in our previous report that advanced glycation end-products (AGEs) stimulated calcium deposition in vascular smooth muscle cells (VSMCs) through excessive oxidative stress and phenotypic transition into osteoblastic cells. Since AGEs can induce apoptosis, in this study we investigated its role on VSMC apoptosis, focusing mainly on the underlying mechanisms. A rat VSMC line (A7r5) was cultured, and treated with glycolaldehyde-derived AGE-bovine serum albumin (AGE3-BSA). Apoptotic cells were identified by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. To quantify apoptosis, an enzyme-linked immunosorbent assay (ELISA) for histone-complexed DNA fragments was employed. Real-time PCR was performed to determine the mRNA levels. Treatment of A7r5 cells with AGE3-BSA from 100 µg/mL concentration markedly increased apoptosis, which was suppressed by Nox inhibitors. AGE3-BSA significantly increased the mRNA expression of NAD(P)H oxidase components including Nox4 and p22(phox), and these findings were confirmed by protein levels using immunofluorescence. Dihydroethidisum assay showed that compared with cBSA, AGE3-BSA increased reactive oxygen species level in A7r5 cells. Furthermore, AGE3-induced apoptosis was significantly inhibited by siRNA-mediated knockdown of Nox4 or p22(phox). Double knockdown of Nox4 and p22(phox) showed a similar inhibitory effect on apoptosis as single gene silencing. Thus, our results demonstrated that NAD(P)H oxidase-derived oxidative stress are involved in AGEs-induced apoptosis of VSMCs. These findings might be important to understand the pathogenesis of vascular calcification in diabetes and CKD.

Osteomalacia caused by atypical renal tubular acidosis with vitamin D deficiency: a case report.

Osteomalacia is a systemic metabolic bone disease. Hypophosphatemia is one of the most important causes of impaired mineralization. Here, we describe a case of osteomalacia associated with atypical renal tubular acidosis. A 43-year-old woman was admitted to our hospital due to sustained unrelieved bilateral flank pain. She had a history of fragile fracture with vitamin D deficiency and had been treated with active vitamin D. On admission, she presented with hypophosphatemia, hypocalcemia, high bone-specific alkaline phosphatase level, bone pain, and low bone mineral density. Multiple areas of uptake were also confirmed by bone scintigraphy, and she was diagnosed with osteomalacia. An increased dose of alfacalcidol was initiated for her vitamin D deficiency; her symptoms remained unstable and unrelieved. Her blood gas examination revealed metabolic acidosis without an increase in the anion gap (HCO3- 11.8 mEq/L, anion gap 3.2 mEq/L). Tubular dysfunction, tubular damage, kidney stones, and inadequate urinary acidification were all observed, suggesting the presence of renal tubular acidosis from a combination of both distal and proximal origin. She also had overt proteinuria, decreased renal function, and hypothalamic hypogonadism. In addition to alfacalcidol, sodium bicarbonate and oral phosphorus supplementation were initiated. After this prescription, her pain dramatically improved in association with the restoration of acid-base balance and electrolytes; renal dysfunction and proteinuria were unaltered. This case indicated that careful assessments of tubular function and acid-base balance are essential for the management of osteomalacia in addition to the evaluation of the calcium/phosphate balance and vitamin D status.

Acute suppurative thyroiditis caused by thyroid papillary carcinoma in the right thyroid lobe of a healthy woman.

BACKGROUND: The thyroid gland is resistant to microbial infection, because of its organ characteristics such as encapsulation, iodine content, and rich blood supply. Therefore, acute suppurative thyroiditis (AST), as a bacterial infection of the thyroid gland, is rarely seen. AST typically takes places on the left side the neck region in children, because of the coincidence of the left piriform sinus fistula, as a most common route of infection. AST is also usually seen in immunocompromised hosts. Herein, we report a rare case of AST in the right thyroid lobe of adult woman without any immunocompromised condition. CASE PRESENTATION: A 59-year-old woman was introduced to our hospital for the further examination with fever, sore throat, and right anterior neck swelling. The patient appeared not to be immunodeficient. Neck ultrasonography showed a 47-mm, hypoechoic, heterogeneous nodule with ill-defined margins and irregular form, suggesting a right thyroid malignant nodule. Fine needle aspiration (FNA) biopsy specimen revealed numerous number of neutrophils in the background without nuclear atypia. Based on the clinical course and cytology, AST was confirmed to be diagnosed. Complete response was obtained by an intravenous administration of antimicrobial agents within a week. Image findings such as CT scan did not show any piriform sinus fistula. Four months later, neck ultrasonography showed a significant decrease in size of the nodule in the right thyroid gland to 27 mm, but the lesion still resembled a malignant nodule. So, FNA was repeated again and cytological examination confirmed papillary thyroid carcinoma (PTC). The patient subsequently underwent total thyroidectomy and bilateral level D1 lymph node dissection. Histological findings revealed a 20-mm PTC in the right lobe with sternothyroid muscle invasion of the tumor. CONCLUSIONS: This report represents a rare case of AST associated with PTC on the right side of thyroid gland, found in a healthy adult woman. The reason why AST coincided with malignant thyroid tumor is unclear. We have to take it into our account that malignant tumor may exist in the background when AST is identified on the right side of thyroid gland with a healthy subject.

Long-term efficacy and safety of vildagliptin add-on therapy in type 2 diabetes mellitus with insulin treatment.

BACKGROUND: The use of dipeptidyl peptidase (DPP)-4 inhibitors in patients with type 2 diabetes treated with insulin may be beneficial. However, the long-term efficacy and safety of vildagliptin add-on therapy in these patients remains unclear. SUBJECTS AND METHODS: A total of 73 patients with type 2 diabetes treated with insulin were randomly assigned to receive either add-on therapy of vildagliptin (n=37) or conventional therapy without DPP-4 inhibitors (n=36) for glucose control. Hemoglobin A1c (HbA1c) levels, dose and number of insulin injections, number of hypoglycemia episodes, and liver and renal function were monitored for 2years. RESULTS: The baseline characteristics of subjects, including age, dose of insulin injections, or HbA1c levels, did not differ between the two groups. In the vildagliptin group, HbA1c levels significantly decreased and the significance of HbA1c reduction was maintained for 24months (from 8.0±1.2% to 7.4±1.0%, p<0.05, at the end of observational period). In addition, the dose and number of insulin injections significantly reduced (-5.6units, p<0.01, and -0.9 times, p<0.001). However, these parameters were unchanged in the control group. The number of patients who experienced three or more episodes of hypoglycemia per year was significantly lower in the vildagliptin group (n=4) than in the control group (n=11) (odds ratio, 0.28; 95% confidence interval, 0.08-0.97; p<0.05). CONCLUSION: Vildagliptin as an add-on to insulin treatment for 24months was well tolerated and led to sustained reductions in HbA1c, the dose and number of insulin injections, and the risk of hypoglycemia.