Reducing Oxidative Stress and Inflammation by Pyruvate Dehydrogenase Kinase 4 Inhibition Is Important in Prevention of Renal Ischemia-Reperfusion Injury in Diabetic Mice.

BACKGRUOUND: Reactive oxygen species (ROS) and inflammation are reported to have a fundamental role in the pathogenesis of ischemia-reperfusion (IR) injury, a leading cause of acute kidney injury. The present study investigated the role of pyruvate dehydrogenase kinase 4 (PDK4) in ROS production and inflammation following IR injury. METHODS: We used a streptozotocin-induced diabetic C57BL6/J mouse model, which was subjected to IR by clamping both renal pedicles. Cellular apoptosis and inflammatory markers were evaluated in NRK-52E cells and mouse primary tubular cells after hypoxia and reoxygenation using a hypoxia work station. RESULTS: Following IR injury in diabetic mice, the expression of PDK4, rather than the other PDK isoforms, was induced with a marked increase in pyruvate dehydrogenase E1α (PDHE1α) phosphorylation. This was accompanied by a pronounced ROS activation, as well as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1ß (IL-1ß), and monocyte chemoattractant protein-1 (MCP-1) production. Notably, sodium dichloroacetate (DCA) attenuated renal IR injury-induced apoptosis which can be attributed to reducing PDK4 expression and PDHE1α phosphorylation levels. DCA or shPdk4 treatment reduced oxidative stress and decreased TNF-α, IL-6, IL-1ß, and MCP-1 production after IR or hypoxia-reoxygenation injury. CONCLUSION: PDK4 inhibition alleviated renal injury with decreased ROS production and inflammation, supporting a critical role for PDK4 in IR mediated damage. This result indicates another potential target for reno-protection during IR injury; accordingly, the role of PDK4 inhibition needs to be comprehensively elucidated in terms of mitochondrial function during renal IR injury.

The Ratio of Estimated Glomerular Filtration Rate Based on Cystatin C and Creatinine Reflecting Cardiovascular Risk in Diabetic Patients.

BACKGROUND: The ratio of estimated glomerular filtration rate (eGFR) based on cystatin C and creatinine (eGFRcystatin C/eGFRcreatinine ratio) is related to accumulating atherosclerosis-promoting proteins and increased mortality in several cohorts. METHODS: We assessed whether the eGFRcystatin C/eGFRcreatinine ratio is a predictor of arterial stiffness and sub-clinical atherosclerosis in type 2 diabetes mellitus (T2DM) patients, who were followed up during 2008 to 2016. GFR was estimated using an equation based on cystatin C and creatinine. RESULTS: A total of 860 patients were stratified according to their eGFRcystatin C/eGFRcreatinine ratio (i.e., <0.9, 0.9-1.1 [a reference group], and >1.1). Intima-media thickness was comparable among the groups; however, presence of carotid plaque was frequent in the <0.9 group (<0.9 group, 38.3%; 0.9-1.1 group, 21.6% vs. >1.1 group, 17.2%, P<0.001). Brachial-ankle pulse wave velocity (baPWV) was faster in the <0.9 group (<0.9 group, 1,656.3±333.0 cm/sec; 0.9-1.1 group, 1,550.5±294.8 cm/sec vs. >1.1 group, 1,494.0±252.2 cm/sec, P<0.001). On comparing the <0.9 group with the 0.9-1.1 group, the multivariate-adjusted odds ratios of prevalence of high baPWV and carotid plaque were 2.54 (P=0.007) and 1.95 (P=0.042), respectively. Cox regression analysis demonstrated near or over 3-fold higher risks of the prevalence of high baPWV and carotid plaque in the <0.9 group without chronic kidney disease (CKD). CONCLUSION: We concluded that eGFRcystatin C/eGFRcreatinine ratio <0.9 was related to an increased risk of high baPWV and carotid plaque in T2DM patients, especially, those without CKD. Careful monitoring of cardiovascular disease is needed for T2DM patients with low eGFRcystatin C/eGFRcreatinine ratio.

Relative handgrip strength as a marker of metabolic syndrome: the Korea National Health and Nutrition Examination Survey (KNHANES) VI (2014-2015).

Purpose: Muscles play an important role in energy metabolism. Several studies have investigated the association between muscle mass and metabolic syndrome (MetS), reporting conflicting results. However, studies concerning the association between muscle strength and MetS are limited. We aimed to investigate the association between relative handgrip strength (HGS) and MetS in Korean adults. Participants and methods: We analyzed data from 5,014 Korean adults aged ≥20 years (2,472 men and 2,542 women) who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) VI (2014-2015). Results: The increasing quartiles of relative HGS (defined as the sum of both hands' HGS divided by body mass index) were inversely associated with the risk of MetS in both men and women (OR, 0.37; 95% CI, 0.30-0.45, vs OR, 0.19; 95% CI, 0.14-0.27, respectively) after multivariable adjustment for age, region of residence, smoking status, heavy alcohol consumption, regular exercise, family income, and education level. On multivariable logistic regression analyses, participants with the highest relative HGS had a significant decrease in relative risk of MetS, compared with those with the lowest relative HGS. The multivariable-adjusted ORs (with 95% CIs) for MetS in quartiles 1, 2, 3, and 4 were 1.00, 0.72 (0.55-0.94), 0.34 (0.26-0.46), and 0.22 (0.15-0.32) in men and 1.00, 0.50 (0.36-0.68), 0.26 (0.17-0.40), and 0.16 (0.09-0.27) in women, respectively. Conclusion: Relative HGS showed a highly significant inverse association with the risk of MetS in Korean adults, and it can be a novel biomarker for assessing the risk of MetS.

Association between serum cystatin C and bone mineral density in Korean adults.

Background: Serum cystatin C has been known as a novel marker of preclinical renal dysfunction, and higher cystatin C levels are associated with increased risks of hip and nonvertebral fractures. However, there are few reports on the association between serum cystatin C and bone mineral density (BMD), especially in the Asian population. We evaluated the association between cystatin C levels and BMD of the spine and hip in Korean adults. Methods: A cross-sectional study was performed in 865 Korean adults (325 men and 540 women) who participated in a comprehensive medical examination program and underwent bone densitometry. Renal function was assessed by the estimated glomerular filtration rate (eGFR), which was calculated using an equation based on creatinine (eGFRcre) and cystatin C (eGFRcys). Results: The serum cystatin C level was negatively correlated with different types of BMD, including the lowest lumbar, total lumbar, femoral neck, and total femur BMD, in women, but not in men. Higher cystatin C levels were associated with a higher prevalence of osteoporosis in women (odds ratio [OR], 3.68; 95% confidence interval [CI], 1.69-8.03; P=0.001), but not in men (OR, 0.85; 95% CI, 0.30-2.38; P=0.761). However, this association was attenuated in the multivariable model adjusted for age, body mass index, serum 25-hydroxyvitamin D3, and creatinine (OR, 1.01; 95% CI, 0.38-2.71) in women. In addition, the eGFRcys showed a stronger positive correlation with BMD than the eGFRcre. Conclusion: Our findings suggest that serum cystatin C levels might help identify women with osteoporosis who are susceptible to fractures.

Sex differences in the prevalence of metabolic syndrome and its components in hypopituitary patients: comparison with an age- and sex-matched nationwide control group.

PURPOSE: Hypopituitary patients have a reduced life expectancy owing to cardiovascular events. We investigated the prevalence of metabolic syndrome in hypopituitary patients for a follow-up period of at least 1 year in comparison with an age- and sex-matched nationwide control group. METHODS: A total of 515 patients with hypopituitarism who visited Seoul National University Hospital between January 2000 and December 2010 were included. Data for an age- and sex-matched control group were obtained from the Korean National Health and Nutrition Examination Surveys (KNHANES) (n = 1545). Metabolic syndrome was defined according to the modified National Cholesterol Education Program (NCEP-ATPIII). RESULTS: The prevalence of metabolic syndrome did not differ significantly between the hypopituitary and control groups for men (34.9 versus 30.3 %), but the risk of metabolic syndrome was higher in hypopituitary women than in controls (39.8 versus 28.5 %). In both sexes, the risks of central obesity and dyslipidemia were higher in the hypopituitary group than in the control group. Men had lower risks of hypertension and hyperglycemia in the hypopituitary group, which attenuated the risk of metabolic syndrome. Age greater than 40 years and obesity (BMI ≥25 kg/m2) contributed to a higher risk of metabolic syndrome. CONCLUSIONS: The metabolic syndrome prevalence was higher in the hypopituitry group than in the control group in Korean women, and this was attributed to an increased risk of central obesity and dyslipidemia. Accordingly, early intervention to reduce metabolic syndrome needed in hypopituitary patients, i.e. women.

The risk of second primary malignancy is increased in differentiated thyroid cancer patients with a cumulative (131)I dose over 37 GBq.

BACKGROUND: The aim of this study was to investigate the risk factors for second primary malignancy (SPM) diagnosed after differentiated thyroid cancer (DTC). METHODS: A total of 2468 DTC patients who underwent thyroidectomy were reviewed. SPM was defined as a non-thyroidal malignancy, diagnosed at least 1 year after the diagnosis of thyroid cancer. Patients were divided into five groups according to cumulative (131)I dose: very high-activity (≥ 37.0 GBq), high-activity (22.3-36.9 GBq), intermediate-activity (5.56-22.2 GBq), low-activity (1.1-5.55 GBq) and no RAI. RESULTS: Among the 2468 patients, 61 (2.5%) had SPMs during 7.0 (1.0-33.0) years of median follow-up. Age above 40 years, male sex and very high-activity RAI were independent risk factors for the development of SPM. SPM-related mortality was highest in the very high-activity group, while DTC-related mortality was highest in the high-activity group. The overall mortality both from SPM and DTC was highest in the high-activity group. CONCLUSION: A cumulative (131)I dose <37.0 GBq did not increase the risk of SPM. A cumulative (131) I dose ≥ 37.0 GBq increased the risk of SPM and SPM-related mortality and decreased the DTC-specific mortality, resulting in a similar all-cause mortality compared with the low-activity RAI group. Using repeated high-dose RAI for treating RAI-responsive but persistent DTC patients needs careful consideration of the individual benefits from RAI vs the risk of developing SPM.