Young Seol Kim

Soybean ethanol extract increases the function of osteoblastic MC3T3-E1 cells.

To investigate the bioactivities of soybean, which act on bone metabolism, we studied the effect of a soybean ethanol extract on the activity of osteoblast MC3T3-E1 cells. Soy extract (0.01-0.1 g/l) dose-dependently increased survival (P<0.05) and DNA synthesis (P<0.05) of MC3T3-E1 cells. In addition, soy extract (0.05 g/l) increased alkaline phosphatase activity (P<0.05) and collagen synthesis (P<0.05) of MC3T3-E1 cells. Moreover, the anti-estrogen tamoxifen eliminated the stimulation of MC3T3-E1 cells on the proliferation, ALP activity and collagen synthesis by soy extract, indicating that the main action of the soy extract on osteoblastic MC3T3-E1 cells is similar to that of estrogen effects. Treatment with soy extract prevented apoptosis, as assessed by a one-step sandwich immunoassay and DNA gel electrophoresis studies. This effect may be associated with the activation of the estrogen receptor, since we observed soy extract-mediated survival against apoptosis was blocked by the estrogen receptor antagonist tamoxifen in cells, further supporting a receptor-mediated mechanism of cell survival. These results suggest that osteoblast function is promoted by soy extract and that the estrogen receptor is involved in the response, thereby playing an important role in bone remodeling. In conclusion, soy extract has a direct stimulatory effect on bone formation in cultured osteoblastic cell in vitro. Presumably, dietary soy products are useful in the prevention of osteoporosis.

Sarcopenia is independently associated with cardiovascular disease in older Korean adults: the Korea National Health and Nutrition Examination Survey (KNHANES) from 2009.

Background The association between sarcopenia and cardiovascular disease (CVD) in elderly people has not been adequately assessed. The aim of this study was to investigate whether CVD is more prevalent in subjects with sarcopenia independent of other well-established cardiovascular risk factors in older Korean adults. Method This study utilized the representative Korean population data from the Korea National Health and Nutrition Examination Survey (KNHANES) which was conducted in 2009. Subjects older than 65 years of age with appendicular skeletal muscle mass (ASM) determined by dual energy X-ray absorptiometry were selected. The prevalence of sarcopenia in the older Korean adults was investigated, and it was determined whether sarcopenia is associated with CVD independent of other well-known risk factors. Results 1,578 subjects aged 65 years and older with the data for ASM were selected, and the overall prevalence of sarcopenia was 30.3% in men and 29.3% in women. Most of the risk factors for CVD such as age, waist circumference, body mass index, fasting plasma glucose and total cholesterol showed significant negative correlations with the ratio between appendicular skeletal muscle mass and body weight. Multiple logistic regression analysis demonstrated that sarcopenia was associated with CVD independent of other well-documented risk factors, renal function and medications (OR, 1.768; 95% CI, 1.075–2.909, P = 0.025). Conclusions Sarcopenia was associated with the presence of CVD independent of other cardiovascular risk factors after adjusting renal function and medications.

Non-association of estrogen receptor genotypes with bone mineral density and bone turnover in Korean pre-, peri-, and postmenopausal women

Abstract: Estrogen is known to play a critical role in both skeletal maturity and the rate of bone loss. This suggests the possibility that the estrogen receptor (ER) gene is one of the candidate genes that determines peak bone density and/or bone turnover rate. We investigated two established restriction fragment length polymorphisms (RFLPs) in intron 1 at the ER gene, represented as PvuII and XbaI. In 598 healthy Korean women aged 20–74 years, we examined the association of these ER genotypes with bone mineral density (BMD) and bone turnover status. The distribution of the PvuII and XbaI RFLPs was as follows: pp 205 (34.3%), Pp 308 (51.5%), PP 85 (14.2%) and xx 384 (64.2%), Xx 180 (30.1%), XX 34 (5.7%), respectively (where capital letters signify the absence of, and lower-case letters signify the presence of, the restriction site of each RFLP). No significant genotypic differences were found in BMD and bone markers. We grouped the subjects into three categories according to their menstrual status: 104 premenopausal women with regular menstruation, 182 perimenopausal women who had amenorrhea of not less than 3 months and not more than 12 months’ duration, and 312 postmenopausal women whose last menstruation was at least 12 months previously. No significant genotypic difference in either BMD or bone markers was found in any of these three groups. Furthermore we categorized women in peri- and postmenopause into a high loser group and a normal loser group according to the level of bone resorption markers. There was no difference in genotypic proportions between the high and normal loser groups. Our data suggest that these ER polymorphisms are not associated with BMD or bone turnover in Korean women.

Mitochondria-targeted antioxidants protect pancreatic β-cells against oxidative stress and improve insulin secretion in glucotoxicity and glucolipotoxicity.

Mitochondrial oxidative damage is thought to play a key role in pancreatic β-cell failure in the pathogenesis of type 2 diabetes. Despite this, the potential of mitochondria-targeted antioxidants to protect pancreatic β-cells against oxidative stress has not yet been studied. Therefore, we investigated if mitochondria-targeted antioxidants protect pancreatic β-cells such as RINm5F and HIT-T15 cells against oxidative stress under glucotoxic and glucolipotoxic conditions. When β-cells were incubated under these conditions, the expression levels of mitochondrial electron transport chain complex subunits, mitochondrial antioxidant enzymes (such as MnSOD and Prx3), β-cell apoptosis, lipogenic enzymes (such as ACC, FAS and ABCA1), intracellular lipid accumulation, oxidative stress, ER stress, mitochondrial membrane depolarization, nuclear NF- ĸB and sterol regulatory element binding protein 1c (SREBP1c) were all increased, in parallel with decreases in intracellular ATP content, citrate synthase enzymatic activity and glucose-stimulated insulin secretion. These changes were consistent with elevated mitochondrial oxidative stress, and incubation with the mitochondria-targeted antioxidants, MitoTempol or Mitoquinone (MitoQ), prevented these effects. In conclusion, mitochondria-targeted antioxidants protect pancreatic β-cells against oxidative stress, promote their survival, and increase insulin secretion in cell models of the glucotoxicity and glucolipotoxicity associated with Type 2 diabetes.

C1q/TNF-Related Protein-3 (CTRP-3) and Pigment Epithelium-Derived Factor (PEDF) Concentrations in Patients With Type 2 Diabetes and Metabolic Syndrome

Recent studies have suggested that a novel adipokine, C1q/tumor necrosis factor-related protein-3 (CTRP-3), a paralog of adiponectin, may play an important role in the regulation of glucose metabolism and innate immunity. Pigment epithelium-derived factor (PEDF), a multifunctional protein with antioxidant and anti-inflammatory properties, is associated with insulin resistance and metabolic syndrome. We examined circulating CTRP-3 and PEDF concentrations in 345 subjects with diverse glucose tolerance statuses. Furthermore, we evaluated the involvement of CTRP-3 and PEDF with cardiometabolic risk factors including insulin resistance, high-sensitivity C-reactive protein (hsCRP), estimated glomerular filtration rate (eGFR), and brachial-ankle pulse wave velocity (baPWV). CTRP-3 concentrations were significantly higher in patients with type 2 diabetes or prediabetes than the normal glucose tolerance group, whereas PEDF levels were not different. Subjects with metabolic syndrome showed significantly higher levels of both CTRP-3 and PEDF compared with subjects without metabolic syndrome. Both CTRP-3 and PEDF were significantly associated with cardiometabolic parameters, including waist-to-hip ratio, triglycerides, HDL-cholesterol, alanine aminotransferase, eGFR, hsCRP, and baPWV. In conclusion, circulating CTRP-3 concentrations were elevated in patients with glucose metabolism dysregulation. Both CTRP-3 and PEDF concentrations were increased in subjects with metabolic syndrome and associated with various cardiometabolic risk factors.

Prevalence of Chronic Complications in Korean Patients with Type 2 Diabetes Mellitus Based on the Korean National Diabetes Program

Background The Korean National Diabetes Program (KNDP) cohort study is performing an ongoing large-scale prospective multicenter investigation to discover the pathogenesis of type 2 diabetes in Korean patients. This study was performed to examine the prevalence of chronic complications in patients with type 2 diabetes among those registered in the KNDP cohort within the past 4 years. Methods This study was performed between June 2006 and September 2009 at 13 university hospitals and included 4,265 KNDP cohort participants. Among the participants, the crude prevalence of microvascular and macrovascular diseases of those checked for diabetes-related complications was determined, and the adjusted standard prevalence and standardization of the general population prevalence ratio (SPR) was estimated based on the 2005 Korean National Health and Nutrition Examination Survey (KNHANES) population demographics. Results Among the KNDP registrants, 43.2% had hypertension, 34.8% had dyslipidemia, 10.8% had macrovascular disease, and 16.7% had microvascular disease. The SPR of the KNDP registrants was significantly higher than that of the KNHANES subjects after adjusting for demographics in the KNHANES 2005 population. However, with the exception of cardiovascular disease in females, the standardized prevalence for the most complicated items in the survey was significantly higher than that in the KNHANES subjects. Conclusion The prevalence of macrovascular disease and peripheral vascular disease were significantly higher in Korean patients with type 2 diabetes than in the normal population. However, no significant difference was noted in the prevalence of cardiovascular disease in females.

Kaempferol protects HIT-T15 pancreatic beta cells from 2-deoxy-D-ribose-induced oxidative damage

During the progression of Type 2 diabetes, glucose toxicity is likely to contribute importantly to progressive beta cell failure. Oxidative stress is an important aspect of glucose toxicity in pancreatic beta cells, and reducing sugars, such as 2‐deoxy‐D‐ribose (dRib), produce reactive oxygen species. Furthermore, many of the biological properties of flavonoids are likely to be related to their antioxidant and free‐radical scavenging abilities. Accordingly, in the present study, we investigated whether kaempferol (a flavonol) protects beta cells from dRib‐induced oxidative damage. HIT‐T15 cells were cultured with various concentrations of dRib for 24h. Cell survivals, amounts of reactive oxygen species (ROS) generated, apoptosis, and lipid peroxidation were measured. dRib was found to dose‐dependently reduce cell survival and to markedly increase intracellular ROS levels, apoptosis, and lipid peroxidation. However, kaempferol (10 µM) suppressed dRib (20 mM) induced intracellular ROS, apoptosis, and lipid peroxidation. So, we demonstrate that kaempferol reduces dRib‐mediated beta cell damage interfering with ROS metabolism and protective effects against lipid peroxidation. Our findings indicate that kaempferol protects HIT‐T15 cells from dRib‐induced associated oxidative damage. Copyright

Atrial natriuretic factor is released from rat hypothalamus in vitro

In vitro release of atrial natriuretic factor (ANF) from rat hypothalamic fragment during 60 min incubation was studied using a specific and sensitive radioimmunoassay (RIA). The Sephadex G-75 gel filtration profiles of the incubation medium revealed that the majority of released ANF-like immunoreactivity (LI) had a molecular weight same as alpha-atrial natriuretic polypeptide and a small amount of ANF-LI of larger molecular size was also released. The release of ANF was increased by addition of 50 mM KCl and the release by 50 mM KCl was completely suppressed in the presence of 2 mM EGTA, a chelating agent of Ca2+. A23187, a Ca2+ ionophore, at a concentration of 2 X 10(-4) M augmented the release of ANF-LI. These results indicate that hypothalamic ANF is released in a Ca2+-dependent manner like other hypothalamic peptides. This suggests that hypothalamic ANF acts as a neurotransmitter and/or neuromodulator in the hypothalamus and possesses some role in the regulation of pituitary hormone secretion.

Polymorphisms in Interleukin-1β and Interleukin-1 Receptor Antagonist Genes Are Associated with Kidney Failure in Korean Patients with Type 2 Diabetes mellitus

Background/Aim: Cytokines play an important role in the pathogenesis of kidney diseases. The aim of the study was to investigate the impact of interleukin (IL)-1 cluster genes on diabetic nephropathy in Korean patients with type 2 diabetes mellitus (DM). Methods: We investigated –511 C/T polymorphism of IL-1β and tandem repeat polymorphism in intron 2 of IL-1 receptor antagonist in type 2 DM patients with end-stage kidney failure as compared with patients without nephropathy. Results: The IL1B2 allele was found more frequently in patients with kidney failure than in controls (57.4 vs. 46.1%, p < 0.05). An excessive homozygous carriage of IL1B2 was found in patients with kidney failure when compared with controls (30.5 vs. 18.3%, p < 0.05). The allelic frequency of IL1RN*2 was also higher in cases than in controls without nephropathy (8.4 vs. 2.8 %, p < 0.05). The carriage rate of IL1RN*2 was significantly associated with an increased risk of kidney failure (15.8 vs. 5.6%; OR 3.19, 95% CI 1.24–8.17). The risk of kidney failure was highest in those carrying both IL1RN*2 and IL1B2 (OR 3.90, 95% CI 1.34–11.40). Conclusion: IL1B2 and IL1RN*2 genotypes of the IL-1 cluster genes are associated with diabetic nephropathy in Korean patients with type 2 DM.

Blood lead is significantly associated with metabolic syndrome in Korean adults: an analysis based on the Korea National Health and Nutrition Examination Survey (KNHANES), 2008

BackgroundAlthough an association between low-level environmental heavy metal exposure and the incidence of metabolic syndrome (MS) has been hypothesized, little research on this topic has been conducted on a population-wide level.MethodsWe analyzed MS status and whole blood lead, mercury, cadmium, manganese, and creatinine-adjusted urine arsenic concentrations in 1,405 subjects, ≥ 20 years of age, who were registered for the Korea National Health and Nutrition Examination Survey, 2008.ResultsVarious demographic and biochemical parameters were associated with MS and blood heavy metal status. After adjusting for these variables, lead was the only heavy metal that was significantly associated with MS. Lead concentrations in subjects with MS were significantly higher than those in subjects without MS (p = 0.015). The prevalence of MS and a moderate/high risk for cardiovascular disease, as determined by Framingham risk score, also increased significantly according to the logarithmic transformation of the lead quartile (p < 0.001). The odds ratios and 95% confidence intervals for MS were 1.56 (0.90–2.71), 1.63 (0.94–2.83), and 2.57 (1.46–4.51) for the second, third, and fourth quartiles of the log-transformed lead quartile, respectively, as compared with those of the lowest quartile after multiple adjustments for confounding factors. Serum triglyceride level was the only MS diagnostic component significantly associated with lead level in a multiple linear regression analysis (p = 0.006).ConclusionsThese findings suggest that a higher prevalence of MS is associated with higher blood lead levels in the Korean population.