Sung Wook Kang

Renoprotective effect of Tanshinone IIA, an active component of Salvia miltiorrhiza, on rats with chronic kidney disease.

Chronic kidney disease (CKD) is a common cause of end‐stage renal disease. Antihypertensive agents are used clinically to inhibit the progression of CKD, but cannot prevent eventual renal failure. This study investigated the effect of Tanshinone IIA, an active component of Salvia miltiorrhiza, in rats suffering from CKD induced by 5/6 nephrectomy. After development of renal insufficiency, the rats were treated with Tanshinone IIA (10 mg/kg) for 8 weeks. Serum creatinine, angiotensin II (Ang II), transforming growth factor β1 (TGF‐β1) and collagen IV levels were significantly reduced in Tanshinone IIA treated rats compared with a control group. In addition, Tanshinone IIA suppressed increases in urinary protein excretion in CKD rats. These findings suggest that chronic oral administration of Tanshinone IIA can improve renal dysfunction associated with CKD. Copyright

Effects of nicotine on apoptosis in human gingival fibroblasts

AIM Cigarette smoke is a complex mixture of more than 4700 chemical compounds including free radicals and oxidants and it is a world widely known problem to health. Nicotine is the major compound of tobacco and known as the cause of gingivitis and periodontitis. It induces intracellular oxidative stress recognized as the important agent in the damage of biological molecules. The aim of this study is to clarify the cytotoxic pathway of nicotine in human gingival fibroblasts (HGFs). METHODS Human gingival fibroblasts stimulated by nicotine were used as an in vitro model. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect cell viability and reactive oxygen species (ROS) generation was assessed with 2,7-dichlorofluoroscein diacetate (DCF-DA). Morphological change was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labelling (TUNEL) assay, stained with 4,6-diamidino-2-phenylindole (DAPI). To delineate the roles of extracellular signal-regulated kinase (ERK), P38 and c-Jun N-terminal kinase (JNK), Western blot and caspase-3 (CASP3) activity assay were performed. RESULTS Exposure of the human gingival fibroblasts to nicotine reduced cell viability by time and dose dependent and increased the generation of ROS. It also showed morphological evidence of increased apoptosis, resulted in transient activation of JNK and ERK concomitant with activation of P38, and stimulated apoptosis as evidenced by CASP3 activation and Poly ADP ribose polymerase (PARP) cleavage. CONCLUSION These results suggest that nicotine induces apoptosis through the ROS generation and CASP3 dependent pathways in HGFs.

Therapeutic Effect of Korean Red Ginseng on Inflammatory Cytokines in Rats with Focal Cerebral Ischemia/Reperfusion Injury

This study aims to identify the therapeutic effect of Korean red ginseng (KRG) on the expression of inflammatory cytokines in rats with focal cerebral ischemia/reperfusion injury. Adult male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion (tMCAO) for two hours. They were fed KRG extract (100 mg/kg/day per orally) or saline after reperfusion. Tests for neurological deficits, using the modified neurologic severity score and the corner turn test, were performed before the ischemic event, and one, three, and seven days after tMCAO. Serum levels of cytokines were measured three and seven days after the operation, using enzyme-linked immunosorbent assays. The infarct volume was assessed after seven days by staining brain tissue with 2% 2, 3, 5-triphenyltetrazolium chloride. Oral administration of KRG significantly reduced the infarct volumes and rapidly improved neurological deficits. Serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-6 were higher in tMCAO-operated rats than in the sham-operated rats. These changes were attenuated by daily KRG intake for seven days. Serum IL-10 levels were significantly increased in KRG-fed rats, as compared to sham-operated and saline-fed rats. Our results suggested that KRG provides neuroprotection for rats with focal cerebral ischemia/reperfusion injury. This neuroprotection may be due to raised IL-10 expression and a reduction in the serum levels of TNF-α, IL-1β, and IL-6.

Neuroprotective effects of magnesium-sulfate on ischemic injury mediated by modulating the release of glutamate and reduced of hyperreperfusion.

This study examined the neuroprotective effects of magnesium-sulfate (MgSO(4)) on the cerebral blood flow (CBF) and extracellular glutamate concentration in an eleven vessel occlusion (11VO) rat model. Twenty-one male Sprague-Dawley rats (250-350g) were used for the 11VO ischemic model, which was induced by a 10-min transient occlusion. The animals were divided into 3 groups, including ischemic-induced animals (ischemia group), ischemic-induced and MgSO(4) treated animals (MgSO(4) group), and sham animals for comparison. The real-time extracellular glutamate concentration was measured using a microdialysis biosensor, and the CBF was monitored by laser Doppler flowmetry. Neuronal cell death in the hippocampal region was observed 72h after ischemia by several stains (Nissl, DAPI, NeuN, and cleaved caspase3). A significant decrease in %CBF was observed in both the ischemia and MgSO(4) groups, such as ~10% during the ischemic period. However, the MgSO(4) group showed a significant decrease in the initial reperfusion %CBF compared to the ischemia group. A significantly lower level of glutamate release was observed in the MgSO(4) group than in the ischemia group during the ischemic and reperfusion episode. Our staining results revealed a significant decrease in neuronal cell death in the hippocampus in the MgSO(4) group compared to the ischemia group. These results suggest that MgSO(4) is responsible for the protection of neuronal cells by suppressing the release of extracellular glutamate under ischemic conditions and the CBF response during the initial reperfusion period.

Association between interleukin 15 receptor, alpha (IL15RA) polymorphism and Korean patients with ossification of the posterior longitudinal ligament

OBJECTIVES Recently, a number of evidences have been reported concerning the genetic factor involved in the development of ossification of the posterior longitudinal ligament (OPLL). The purpose of this study was to investigate single nucleotide polymorphisms (SNPs) of the interleukin 15 receptor, alpha (IL15RA) gene as a risk factor in Korean patients with OPLL. DESIGN To investigate the genetic association, two coding SNPs (rs2296139, Thr73Thr; rs2228059, Asn182Thr) in IL15RA were genotyped in 166 OPLL patients and 230 control subjects. SNPStats, SNPAnalyzer, and Helixtree programs were used for association analysis. RESULTS In the present study, we found the association between a missense SNP (rs2228059) and the risk of OPLL in codominant (p = 0.0028, OR = 1.58, 95% CI = 1.17-2.14), dominant (p = 0.0071, OR = 1.82, 95% CI = 1.17-2.82), and recessive models (p = 0.036, OR = 1.79, 95% CI = 1.04-3.09). The frequency of rs2228059 allele was significantly associated with the susceptibility of OPLL (p = 0.0043, OR = 1.52, 95% CI = 1.14-2.02). After Bonferroni correction, the missense SNP (rs2228059, Asn182Thr) still had significant correlations (p = 0.0056 in codominant model; p = 0.0142 in dominant model; p = 0.0086 in allele analysis). Haplotype variation in IL15RA was associated with OPLL (global haplotype test, p = 0.025). CONCLUSIONS These results suggest that IL15RA polymorphism may be associated with the susceptibility of OPLL in Korean population.

No association between polymorphisms of WNT2

BackgroundWingless-type MMTV integration site family member 2 (WNT2) has a potentially important role in neuronal development; however, there has yet to be an investigation into the association between single nucleotide polymorphisms (SNPs) of WNT2 and schizophrenia. This study aimed to determine whether certain SNPs of WNT2 were associated with schizophrenia in a Korean population.Methodse genotyped 7 selected SNPs in the WNT2 gene region (approximately 46 Kb) using direct sequencing in 288 patients with schizophrenia and 305 healthy controls.ResultsOf the SNPs examined, one SNP showed a weak association with schizophrenia (p = 0.017 in the recessive model). However, this association did not remain statistically significant after Bonferroni correction.ConclusionThe present study does not support a major role for WNT2 in schizophrenia. This could be due to the size of the population. Therefore, additional studies would be needed to definitively rule out the genes minor effects.

Label-free and quantitative evaluation of cytotoxicity based on surface nanostructure and biophysical property of cells utilizing AFM.

In this study, the four commonly used cytotoxicity assays and the mechanical properties as evaluated by atomic force microscopy (AFM) were compared in a cellular system. A cytotoxicity assay is the first and most essential test to evaluate biocompatibility of various toxic substances. Many of the cytotoxicity methods require complicated and labor-intensive process, as well as introduce experimental error. In addition, these methods cannot provide instantaneous and quantitative cell viability information. AFM has become an exciting analytical tool in medical, biological, and biophysical research due to its unique abilities. AFM-based force-distance curve measurements precisely measure the changes in the biophysical properties of the cell. Therefore, we observed the morphological changes and mechanical property changes in L929 cells following sodium lauryl sulfate (SLS) treatment utilizing AFM. AFM imaging showed that the toxic effects of SLS changed not only the spindle-like shape of L929 cells into a round shape, but also made a rough cell surface. As the concentration of SLS was increased, the surface roughness of L929 cell was increased, and stiffness decreased. We confirmed that inhibition of proliferation clearly increased with increases in SLS concentration based on results from MTT, WST, neutral red uptake, and LIVE/DEAD viability/cytotoxicity assays. The estimated IC₅₀ value by AFM analysis was similar to those of other conventional assays and was included within the 95% confidence interval range. We suggest that an AFM quantitative analysis of the morphological and biophysical changes in cells can be utilized as a new method for evaluating cytotoxicity.

The effect of extracellular glutamate release on repetitive transient ischemic injury in global ischemia model.

During operations, neurosurgeons usually perform multiple temporary occlusions of parental artery, possibly resulting in the neuronal damage. It is generally thought that neuronal damage by cerebral ischemia is associated with extracellular concentrations of the excitatory amino acids. In this study, we measured the dynamics of extracellular glutamate release in 11 vessel occlusion (VO) model to compare between single occlusion and repeated transient occlusions within short interval. Changes in cerebral blood flow were monitored by laser-Doppler flowmetry simultaneously with cortical glutamate level measured by amperometric biosensor. From real time monitoring of glutamate release in 11 VO model, the change of extracellular glutamate level in repeated transient occlusion group was smaller than that of single occlusion group, and the onset time of glutamate release in the second ischemic episode of repeated occlusion group was delayed compared to the first ischemic episode which was similar to that of single 10 min ischemic episode. These results suggested that repeated transient occlusion induces less glutamate release from neuronal cell than single occlusion, and the delayed onset time of glutamate release is attributed to endogeneous protective mechanism of ischemic tolerance.

Simultaneous, real-time measurement of nitric oxide and oxygen dynamics during cardiac ischemia–reperfusion of the rat utilizing sol–gel-derived electrochemical microsensors

In this study, we simultaneously measured nitric oxide (NO) and oxygen (O2) dynamics in the myocardium during myocardial ischemia-reperfusion (IR) utilizing sol-gel modified electrochemical NO and O2 microsensors. In addition, we attempted to clarify the correlation between NO release in the ischemic period and O2 restoration in the myocardium after reperfusion, comparing a control heart with a remote ischemic preconditioning (RIPC)-treated heart as an attractive strategy for myocardial protection. Rat hearts were randomly divided into two groups: a control group (n=5) and an RIPC group (n=5, with RIPC treatment). Myocardia that underwent RIPC treatment (182±70 nM, p<0.05) released more NO during the ischemic period than those of the control group (63±41 nM). The restoration value of oxygen tension (pO2) in the RIPC group significantly increased and was restored to pre-ischemic levels (92.6±36.8%); however, the pO2 of the control group did not increase throughout the reperfusion period (5.7±7.5%, p=0.001). Myocardial infarct size measurements revealed a significant decrease in cell death in the myocardium region of the RIPC group (41.44±6.42%, p=0.001) compared with the control group (60.05±10.91%). As a result, we showed that the cardioprotective effect of RIPC could be attributed to endogenous NO production during the ischemic period, which subsequently promoted reoxygenation in post-ischemic myocardia during early reperfusion. Our results suggest that the promotion of endogenous formation during an ischemic episode might be helpful as a therapeutic strategy for protecting the myocardium from IR injury. Additionally, our NO and O2 perm-selective microsensors could be utilized to evaluate the effect of drug or treatment.

Matrix metalloproteinase-3 gene polymorphisms are associated with ischemic stroke.

Stroke is a heterogeneous disease caused by different pathogenic mechanisms. Several candidate genes for stroke have been proposed, but few have been replicated. Matrix metalloproteinases (MMPs) are expressed following stroke. We investigated the association of single nucleotide polymorphisms (SNPs) of the MMP3 gene with stroke in the Korean population. This study included 186 stroke patients [116 ischemic stroke (IS) and 70 intracerebral hemorrhage (ICH)] and 668 age-matched control subjects (267 for IS and 401 for ICH). Three SNPs [rs520540 (Ala362Ala), rs602128 (Asp96Asp), and rs679620 (Lys45Glu)] in the coding region of MMP3 were selected and genotyped by direct sequencing. HelixTree, SNPAnalyzer, SNPStats, and Haploview version 4.2 were used to analyze genetic data. Multiple logistic regression models (codominant, dominant, and recessive models) were conducted to evaluate odds ratio, 95% confidence interval, and P value. Three SNPs in the MMP3 gene were significantly associated with IS (P<0.05). The genotype distribution of 3 SNPs differed between the IS and control subjects. However, there was no association of the SNPs between the ICH and control. In analysis of gender, 3 SNPs were also associated with IS in female group (P<0.05). These SNPs remained significantly associated with IS after the Bonferroni correction for multiple testing (P(c)<0.05). Haplotype analysis revealed that no haplotypes were associated with IS or ICH. Overall, the results of our study demonstrate an association of the MMP3 gene with development of IS, and no association of MMP3 with ICH.