[Show abstract][Hide abstract]ABSTRACT: Peroxisome proliferator-activated receptors (PPARs) and related inflammatory and oxidative molecule expression were investigated in a hyperoxaluric rodent model to evaluate the in vivo efficacy of PPAR agonists in preventing renal crystal formation. PPAR expression was examined in a mouse hyperoxaluria kidney stone model induced by daily intra-abdominal glyoxylate injection. Therapeutic effects of the PPARα agonist fenofibrate and PPARγ agonist pioglitazone were also assessed in a 1% ethylene glycol-induced rat model of hyperoxaluria. Crystal formation, inflammation, cell injury, apoptosis, and oxidative stress were compared to those of vehicle-treated controls. Quantitative reverse transcription-polymerase chain reaction revealed that PPARα and PPARγ expression decrease and increase, respectively, during crystal formation in hyperoxaluric kidneys. In addition, PPARα localized to the cytoplasm of both proximal and distal tubular cells, whereas PPARγ accumulated in the nucleus of proximal tubular cells. Furthermore, renal crystal formation was significantly less prevalent in pioglitazone-treated rats but higher in the fenofibrate-treated and fenofibrate/pioglitazone-cotreated groups compared to controls, thus indicating that pioglitazone, but not fenofibrate, markedly decreased cell inflammation, oxidative stress, and apoptosis. Collectively, the results demonstrated that PPARγ suppressed renal crystal formation via its antioxidative and anti-inflammatory effects; however, the renotoxicity of PPARα may elicit the opposite effect.
Full-text available · Article · Feb 2016 · PPAR Research
[Show abstract][Hide abstract]ABSTRACT: DHCR24 encodes 3β-hydroxysterol-Δ(24)-reductase (DHCR24) catalyzing the cholesterol synthesis from desmosterol using the flavin adenine dinucleotide (FAD) as a co-factor. It is generally accepted that U18666a inhibits the reductase activity of DHCR24, but the detailed mechanism remains elusive. To explore the mechanism of the inhibitory effect of U18666a on DHCR24, we performed molecular dynamics (MD) simulations of two complexes including complexes of DHCR24-FAD-desmosterol enzymatic reactive components with and without the inhibitor U18666a. We found that the U18666a bound into the hydrophobic package near the FAD package of DHCR24. Furthermore, binding free energy of DHCR24 and desmosterol without U18666a is -54.86 kcal/mol, while the system with U18666a is -62.23 kcal/mol, suggesting that the affinity of the substrate desmosterol to DHCR24 was increased in response to the U18666a. In addition, U18666a interacts with FAD by newly forming three hydrogen bonds with Lys292, Lys367, and Gly438 of DHCR24. Finally, secondary structural analysis data obtained from the surrounding hot spots showed that U18666a induced dramatic secondary structural changes around the key residues in the interaction of DHCR24, FAD, and desmosterol. Taken together, these results for the first time demonstrate at the molecular structure level that U18666a blocks DHCR24 activity through an allosteric inhibiting mechanism, which may provide new insight into the development of a new type of cholesterol-lowering drug targeting to block the activity of DHCR24.
Article · Jan 2016 · Journal of Molecular Modeling
[Show abstract][Hide abstract]ABSTRACT: Purpose:
Solute carrier family 26 member 6 (SLC26A6) is a multifunctional anion transporter, and plays a critical physiological role in the transport of oxalate anions. Recognizing genetic variant of SLC26A6 will advance our understanding of oxalate transport in the formation of calcium oxalate stone.
Materials and methods:
All non-synonymous SNPs (nsSNPs) reported in human SLC26A6 were investigated using four different in silico tools including SIFT, PROVEAN, PhD-SNP and MutPred. 426 subjects including 225 kidney stone cases and 201 healthy controls were collected for genotyping the candidate disease-associated nsSNP using an allele-specific PCR. Furthermore, the structural consequences due to the mutation were assessed using homology modeling and molecular dynamics simulation methods RESULTS: A nsSNP (rs184187143) was identified more probable disease-associated variant in SLC26A6 gene by in silico screening. The C allele carrier had a 6.1-fold increased kidney stone risk compared with G allele carriers in the nsSNP (OR=6.1; 95%CI, 1.36-27.38; p=0.007). The mutation from arginine to glycine leads to loss of two hydrogen bonds and unstable structure in STAS domain of SLC26A6.
Our results indicate that the variant (G539R) in the SLC26A6 gene is associated with kidney stone risk, and provide a clear clue for further achieving insight into oxalate transport in the kidney stone formation.
[Show abstract][Hide abstract]ABSTRACT: 3β-Hydroxysteroid-Δ24 reductase (DHCR24) is a multifunctional enzyme that localizes to the endoplasmic reticulum and has neuroprotective and cholesterol-synthesizing activities. DHCR24 overexpression confers neuroprotection against apoptosis caused by amyloid β deposition. The present study aimed to construct two recombinant adenoviruses driving DHCR24 expression specifically in neurons. Two SYN1 promoter DNA fragments were obtained from human (h) and rat (r). Recombinant Ad-r(h)SYN1-DHCR24 was transfected into AD-293, N2A (mouse neuroblastoma), and MIN6 (mouse pancreatic carcinoma) cells. Western blot analysis showed DHCR24 was specially expressed in 293 and N2A cells, but no specific band was found in MIN6 cells. This demonstrates that the recombinant adenoviruses successfully express DHCR24, and no expression is observed in non-neuronal cells. TUNEL assay results showed apoptosis was inhibited in adenovirus-transfected neurons. Detecting reactive oxygen species by immunofluorescence, we found that adenovirus transfection inhibits apoptosis through scavenging excess reactive oxygen species. Our findings show that the recombinant DHCR24 adenoviruses induce neuron-specific DHCR24 expression, and thereby lay the foundation for further studies on DHCR24 gene therapy for Alzheimer's disease.
Full-text available · Article · Mar 2014 · Neural Regeneration Research
[Show abstract][Hide abstract]ABSTRACT: Melamine was recently identified as a risk factor for renal calculi following the milk powder contamination in China. However, the long-term natural history of melamine exposure and its renal effects remain unknown. We evaluated renal function and other adverse health effects using a rat model administered melamine and cyanuric aid, considering age and sex.
Twelve male F334/N rats each of ages 6, 10, and 26 weeks (N = 36) were equally assigned to Group M + C or controls. Group M + C rats were administered 12 mg . kg-1 . day-1 of melamine and cyanuric acid for 28 days. Serum and urine samples and kidney sections were evaluated on day 28. Six-week-old male and female F344/N rats were administered 12 mg of melamine and cyanuric acid for 28 days. Body weights were measured weekly; on days 0, 28, 90, and 180 after the 28-day period of melamine and cyanuric acid administration, serum samples and kidney sections were obtained.
Although the control group had no crystals, 6-week-old Group M + C rats had more crystals compared to the 10- and 26-week old Group M + C rats. Male rats also had significantly more crystals than females of the same age. Male rats were affected to a greater extent than females.
Younger rats experienced more severe renal failure and greater renal crystal deposition following melamine and cyanuric acid administration. However, after melamine and cyanuric acid administration cessation, crystal deposition and renal failure improved and did not cause growth arrest. Therefore, early diagnosis of melamine-associated calculi is critical.
Full-text available · Article · Feb 2014 · BMC Research Notes
[Show abstract][Hide abstract]ABSTRACT: 3β-Hydroxysteroid-Δ24 reductase (DHCR24) is an endoplasmic reticulum (ER)-localized multifunctional enzyme that possesses anti-apoptotic and cholesterol-synthesizing activities. Accumulating evidence suggests that ER stress is involved in the pathogenesis of neurodegenerative disease. In this study, we investigated whether DHCR24 may function as a neuroprotective protein under ER stress. Neuroblastoma N2A cells were infected with adenovirus expressing myc-tagged DHCR24 (Ad-DHCR24) or lacZ (Ad-lacZ, serving as a control) and subjected to ER-stress, induced with Tunicamycin (TM). Cells infected with Ad-DHCR24-myc were resistant to TM-induced apoptosis, and showed weaker level of caspase-12 activity. These cells also exhibited lower levels of Bip and CHOP proteins than Ad-LacZ-infected cells. Moreover, a stronger and rapid activation of PERK, and a prolonged activation of JNK and p38 were observed in Ad-LacZ-infected cells. The generation of intracellular reactive oxygen species from ER stress was also diminished by the overexpression of DHCR24. Additionally, intracellular cholesterol level was also elevated in the Ad-DHCR24-infected cells, accompanied by a well-organized formation of caveolae (cholesterol-rich microdomain) on the plasma membrane, and improved colocalization of caveolin-1 and insulin-like growth factor 1 receptor. These results demonstrated for the first time that DHCR24 could protect neuronal cells from apoptosis induced by ER stress.
Full-text available · Article · Jan 2014 · PLoS ONE
[Show abstract][Hide abstract]ABSTRACT: Abstract Background: In view of their high level of variability, autosomal short tandem repeats (STRs) are very useful as markers in the disciplines of forensic and population genetics studies. Aim: To investigate the diversity distributions of allelic frequencies of 15 loci from a sample from the Chinese Xibe ethnic group in Liaoning. Subjects and methods: Fifteen STR loci for 150 unrelated Xibe individuals from Liaoning, China were amplified simultaneously in a fluorescence-based reaction using a 2720 Thermal cycler (ABI). Separation and detection of the amplified product were conducted with the Li-COR 4300 DNA Analyzer. Results: In total, 117 alleles were observed, with the corresponding allele frequencies ranging from 0.001 to 0.507. D18S51 had the highest polymorphism (PIC = 0.840) among all 15 STR loci, whereas TPOX had the lowest (PIC = 0.590). The power of discrimination ranged from 0.801 for TH01 locus to 0.957 for D18S51 locus, whereas the power of exclusion ranged from a minimum 0.316 for TPOX locus to a maximum 0.720 for D21S11 locus. The phylogenetic tree established among worldwide populations showed that the Xibe population is far from other populations. Conclusion: Databases for the 15 STR loci will be useful for personal identification and paternity tests in the Xibe population and for the establishment of phylogenetic relationships between populations.
[Show abstract][Hide abstract]ABSTRACT: The aim of this study was to estimate the allelic frequencies of the 19 STR loci with the Goldeneye™ DNA ID system 20A kit in a sample of 150 Manchu individuals from China to be used for forensic purposes and population studies. The observed heterozygosity(HO)values of these 19 STR loci ranged from 0.600 (D3S1358) to 0.914 (D18S51), the expected (HE) ranged from 0.615 (TPOX) to 0.876 (D16S1043). The power of discrimination (PD) values were found to range from 0.793 (TPOX) to 0.950 (D16S1043) and the probability of exclusion (PE) varies between 0.291 (D3S1358) and 0.825 (D18S51 and Penta E ). Among all the 19 loci, D16S1043 had the highest polymorphism (PIC=0.860), whereas TPOX had the lowest (PIC=0.550). For the 19 loci, the combined power of discrimination and the combined probability of exclusion are 0.9999999999999999999942 and 0.999999996777, respectively. The phylogenetic tree established among worldwide populations shows different populations who say the same language usually have a close genetic relationship with each other across the three language families studied (Sino-Tibetan, Altaic and Arabic).
[Show abstract][Hide abstract]ABSTRACT: The biphenylsulfonacetic acid and its derivatives were found to inhibit ATP hydrolysis by an allosteric mechanism involving tyrosine 486 of HPV6 E1 Helicase as well as tyrosine 492 of HPV 18 E1. A theoretical study on the binding conformations and allosteric function of these inhibitors has been carried out using docking analysis and molecular dynamics (MD) simulation. The appropriate binding orientations and conformations of the (biphenyl-4-ylsulfonyl) acetic acid interacting with HPV 18 E1 were revealed by the docking study. The MD simulation results obtained from NAMD showed that the binding of (biphenyl-4-ylsulfonyl) acetic acid at the site of Tyr492 was stabilizing around the Lys490 of HPV18 E1, the active site of its ATP hydrolysis. And the protein structure near its predicted allosteric and active sites of HPV 18 E1 has been altered after the binding of the inhibitor to the protein E1 with the different second structure type and length, suggesting that this compound could change the structure conformation near the active center of E1, through which exerts its enzyme-inhibiting function. A series of biphenylsulfonacetic acid derivatives, the reported HPV18 E1 inhibitors, have been then analyzed by docking study. The results revealed that all these compounds could stably bind to the protein with a good binding free energy, suggesting these derivatives could exert a similar allosteric effect on the E1 protein. Taken together, these theoretical results can offer useful references for understanding the mechanisms of allosteric effect of these compounds and directing the molecular design of this kind of inhibitor with improved activity.
[Show abstract][Hide abstract]ABSTRACT: To clarify the association between regional variations in urolithiasis incidence and nutrition intake, we evaluated associated data from Japanese national surveys. The incidence of urolithiasis in 12 regions of Japan was calculated from 2005 patient data obtained from 430 hospitals (n = 92,797). Nutrition intake data were obtained from the National Health and Nutrition Survey. We examined the association between urolithiasis incidence and average intake of various types of food or nutrients by region. Continuing surveys in Japan reveal fixed variations in urolithiasis incidence among geographic regions. The national average of patients with urolithiasis was estimated as 203.1 per 100,000 citizens. Regarding food, intake of fruit correlated negatively with the incidence of urolithiasis (r = -0.721, p = 0.008), while intake of eggs (r = 0.537, p = 0.072) and sugar (r = 0.475, p = 0.119) tended to positively correlate with incidence. Regarding nutrients, intake of potassium (r = -0.500, p = 0.098), vitamin K (r = -0.562, p = 0.057), and pantothenic acid (r = -0.560, p = 0.058) tended to negatively correlate with incidence. The incidence of urolithiasis is higher in geographic areas with populations having low fruit and high sugar intake.
[Show abstract][Hide abstract]ABSTRACT: Background:
Matrix Gla protein (MGP) is a molecular determinant regulating vascular calcification of the extracellular matrix. However, it is still unclear how MGP may be involved in crystal formation in the kidney of hyperoxaluric rats.
Male Sprague-Dawley rats were divided into the hyperoxaluric group and control group. Hyperoxaluric rats were administrated by 0.75% ethylene glycol (EG) for up to 8 weeks. Renal MGP expression was detected by the standard avidin-biotin complex (ABC) method. Renal crystal deposition was observed by a polarizing microscope. Total RNA and protein from the rat kidney tissue were extracted. The levels of MGP mRNA and protein expression were analyzed by the real-time polymerase chain reaction (RT-PCR) and Western blot.
Hyperoxaluria was induced successfully in rats. The MGP was polarly distributed, on the apical membrane of renal tubular epithelial cells, and was found in the ascending thick limbs of Henle's loop (cTAL) and the distal convoluted tubule (DCT) in hyperoxaluric rats, its expression however, was present in the medullary collecting duct (MCD) in stone-forming rats. Crystals with multilaminated structure formed in the injurious renal tubules with lack of MGP expression.MGP mRNA expression was significantly upregulated by the crystals' stimulations.
Our results suggested that the MGP was involved in crystals formation by the continuous expression, distributing it polarly in the renal tubular cells and binding directly to the crystals.
Article · Feb 2013 · Kidney and Blood Pressure Research
[Show abstract][Hide abstract]ABSTRACT: Purpose:
Matrix Gla protein (MGP) is a molecular determinant regulating the extracellular matrix calcification. To further confirm whether the MGP genetic polymorphism was universally associated with the risk of kidney stone, we investigated the association of genetic polymorphisms of MGP with kidney stone in the Chinese Han population.
Materials and methods:
728 subjects were recruited for the study. We firstly re-sequenced the human genomic MGP gene including the 1500 bp promoter, 5'-UTR, 4 exons and 3'-untranslated regions, identified single nucleotide polymorphisms (SNPs) in MGP, and performed an association analysis with kidney stones in 54 subjects of the Chinese Han population. A candidate tag SNP was genotyped in total subjects using an allele specific PCR, and further analyzed the association with kidney stone.
We identified 18 polymorphisms including four tag SNPs. A tag SNPrs4236 was associated with kidney stones. The G allele carrier had a 1.373-fold reduced kidney stone risk compared with A allele carriers in SNPrs4236 (odds ratios (OR)=1.373; 95%CI, 1.051-1.793; p=0.019). However, we did not find an association between the polymorphism and clinical characteristics of kidney stones.
Our findings showed that SNPrs4236 of the MGP gene is associated with kidney stones in the Chinese Han population, and influences the genetic susceptibility to kidney stones. In the future, functional assays of the polymorphism should permit a better understanding of the role of MGP genetic variants and kidney stones.
[Show abstract][Hide abstract]ABSTRACT: The objective of this study is to understand pathogenesis of melamine-related kidney stone formation. We investigated the characterization of renal tubular cell under exposure to a mixture of melamine and cyanuric acid in vivo. Male Sprague-Dawley rats were separated into two experimental groups. Treatment group was administered daily with a standard commercial diet mixing with melamine and cyanuric acid, and control group was given a normal diet. Rat kidney specimens were stained with hematoxylin/eosin and the crystals were examined using a polarizing microscope. Renal tubular epithelial cells were observed by transmission electron microscopy. Semiquantitative RT-PCR assay was performed to determine monocyte chemoattractant protein-1 (MCP-1) mRNA expression, a protein in response to various proinflammatory stimuli. Apoptotic cells were examined by TUNEL assay. Melamine-associated crystals formed in glomerulus and wide renal tubule segment including proximal convoluted renal tubules, distal convoluted renal tubules, the limb loops of Henle and medullary collecting ducts in the cortex and medulla. Light microscopy results showed that the crystals lead to tubular lumen dilatation and tubular epithelial cell necrosis. It was observed that nucleus of renal tubular epithelial cells became irregular outlines and condensed, lysosomal-related structures increased, and integrity of renal tubule was deficient under electron microscopy. Apoptotic cells were noted widely in cortex and medulla. MCP-1 mRNA expression was significantly increased in the melamine and cyanuric acid-administrated group. Renal tubular epithelial cell injury, apoptosis and inflammation are involved in melamine-related kidney stone formation. Our findings are important for understanding pathogenesis of melamine-related kidney stone formation and estimating its clinical prognosis.
[Show abstract][Hide abstract]ABSTRACT: Keap1 negatively regulates the function of Nrf2 that is a major activator of genes encoding phase 2 detoxifying enzymes via sequestering cytoplasmic Nrf2 and subsequent degradation through the proteasome system. Reactive cysteine residues of Keap1 could be modified by Michael reaction acceptor molecules. Previous studies have shown that adduction at Cys151 by diethyl maleate (DEM) can give rise to a significant conformational change in Keap1 that leads to the dissociation of Keap1 from CUL3, hence inhibits Nrf2 ubiquitylation. The BTB domain of Keap1 plays a crucial role in both forming self-dimerization and binding to CUL3. In order to better understanding the molecular mechanism how DEM interact with amino acid residues around Cys151, we performed two molecular dynamics (MD) simulations including Keap1-DEM complex and Keapl alone (control group). Interestingly, we found that after a short period of lingering around Cys151, DEM ultimately stabilized in a gap between two specific helixes away from the cavity around Cys151 and induced a concomitant significant conformational change of BTB domain of Keap1. Similar phenomenon, however, was not observed in the control group. These results suggested that DEM could impair the normal function of Keap1 by inducing the conformational change of BTB domain via direct noncovalent bonded interaction. Our research provides a new insight into another way of interaction between Keap1 and DEM in spite of their known Michael addition reaction, by which novel phase2 enzyme inducer drugs with higher specificity could be discovered in the future.
Article · Jul 2012 · Applied Mechanics and Materials
[Show abstract][Hide abstract]ABSTRACT: DHCR24 encodes 3β-hydroxysteroid-Δ24 reductase, catalyzing the conversion of desmosterol to cholesterol. Our previous study demonstrated that DHCR24 exerts an anti-apoptotic function as a reactive oxygen species (ROS) scavenger, for which it needs its FAD-binding domain. The membrane topology of DHCR24 on endoplasmic reticulum (ER) and the functional significance of its FAD-binding domain are not completely understood. Based on the structure predicted by bioinformatics, we studied the membrane topology of DHCR24 in murine neuroblastoma cells (N2A), using the fluorescent protease protection (FPP) technique. We showed that full-length DHCR24 is localized to the membrane of ER, whereas the predicted transmembrane (TM) domain-deleted DHCR24 mutation is localized to the cytoplasm. The change of DHCR24 localization suggests that the N-terminal TM domain is essential for the ER membrane targeting of DHCR24. The FPP assay demonstrated the membrane topology of DHCR24 with an N-terminal luminal/C-terminal cytoplasmic orientation. Measurement of intracellular ROS using H(2)DCFDA revealed that the ROS levels of cells infected by plasmids driving expression of full-length DHCR24 or the TM domain-deleted DHCR24 mutation after H(2)O(2) exposure were lower than those of control cells, suggesting that the ER membrane targeting of DHCR24 is not required for its enzymatic ROS scavenging activity. Confocal fluorescence microscopy revealed that the DHCR24-overexpressed cells were protected from apoptosis in response to oxidative stress, which was accompanied by a decrease in DHCR24 content on the ER and activation of caspase-3, suggesting that the anti-apoptotic function of DHCR24 is associated with its cleavage by caspase.
Article · Feb 2012 · Journal of Molecular Endocrinology
[Show abstract][Hide abstract]ABSTRACT: The growing evidences demonstrated hyperlipidemia in obesity and type 2 diabetes is characterized by high levels of free fatty acids, low-density lipoprotein (LDL), triglyceride, and cholesterol.
We investigated the effect of LDL particles (LDLs) loading on MIN6 cells derived from pancreatic β cells. Exposure of MIN6 cells to LDLs induced apoptosis in dose and time-dependent manner, demonstrated by the TUNEL in situ apoptotic assay. The immunocytochemical analysis and Western blotting revealed that the LDLs-induced apoptosis is associated with the activation of caspase 3 and upregulation of p53. The intracellular concentration of Reactive Oxygen Species (ROS) measured by use of DCFHDA was significantly increased after loading LDLs, demonstrating the induced apoptosis by LDLs loading was mediated through oxidative stress. Addition of reduced form of Glutathione (GSH) in the medium rescued MIN6 cells from apoptosis. The Cellular cholesterol level was increased significantly after LDLs loading, suggesting that the excess cholesterol induced by LDLs loading might contribute to the apoptosis in MIN6s. Agarose electrophoresis demonstrated that the LDLs added to the medium were not oxidized.
Taken together, these results demonstrate that the LDLs loading can induce apoptosis of MIN6 cells mediated by the excess cellular cholesterol and generation of oxidative stress.
Full-text available · Article · Jul 2011 · Lipids in Health and Disease
[Show abstract][Hide abstract]ABSTRACT: In the present study, we investigated the genetic polymorphisms of 6 autosomal STR loci Hum-CSF1PO, D13S317, D5S818, D16S539, TH01, and TPOX in the Xibo population of Liaoning, northeastern China as well as its genetic relationships with other populations in China. No significant deviations from Hardy-Weinberg equilibrium could be found for all loci. Allele frequencies in the Xibo population ranged from 0.001 to 0.507. Among all the 6 loci, D16S539 had the highest polymorphism (PIC=0.8632), whereas TPOX had the lowest (PIC=0.5179). A phylogenic tree was constructed using Poptree 2 software. In the phylogenic tree, Xibo population has a distant relationship with the other populations.
[Show abstract][Hide abstract]ABSTRACT: Molecular docking is a method that mimics the interactions between small ligand and its biomacromolecule receptor. The interactions between ligand and receptor are the process of molecules recognition, which include several intermolecular interactions, like hydrogen bond actions, electrostatic reactions and so on. Molecular docking can predict the binding affinity and mode of action through computational calculation so that could be used for virtual screening of drug. Its application, however, is limited on the virtual screening that is based on that the interaction between small ligand and target protein receptor is covalent bonding action. The present research took the study of interactions between Keapl protein and Michael reaction acceptor molecules as an example to explore possibility of application of molecular docking on investigating the space matching and energy matching between small ligand and active package of protein receptor. Our results demonstrated that molecular docking could also be used for the rapid investigation of matching status between ligand and active package of protein receptor based on the calculation and analysis of action degree and mode of intermolecules, which will provide a basis for virtual screening dependent on that the action mode is covalent binding action between ligand and active package of target protein receptor. Our finding expands the field of application of the molecular docking for virtual screening.
[Show abstract][Hide abstract]ABSTRACT: Melamine was known as a new risk for kidney stone due to recent incidences of milk powder contamination in China. Here, we performed a retrospective study to investigate whether age, gender, and urinary pH affect melamine-associated kidney stone risk.
A retrospective review was performed of 217 children aged less than 3 years old. All children had a history of being fed with Sanlu milk powder contaminated by melamine, and underwent a clinical screening on kidney stone in Shenyang from November 2008 to February 2009. A comparison with the Chi-square was conducted between 83 cases and 125 normal subjects. The difference between children's gender, age, and urinary pH was evaluated.
A total of 208 subjects, 136 boys and 72 girls, were included in the study. Significant association was observed between melamine-associated kidney stone risk and gender [odds ratio (OR), 2.03; 95% confidence interval (CI), 1.11-3.74; P=0.02] and urinary pH (OR, 1.78; 95% CI, 1.01-3.11; P=0.04), respectively. Male children were at about twofold increased melamine-associated kidney stone risk compared with female children. Acidic urine showed about 1.78-fold increased melamine-associated kidney stone risk compared with normal urine.
Our investigation results showed an association of gender and urinary pH with melamine-associated kidney stone formation risk.
Full-text available · Article · May 2011 · Urology Annals
[Show abstract][Hide abstract]ABSTRACT: Type 2 diabetes is often associated with high blood cholesterol. Here, we investigated the effect of cholesterol loading on MIN6 cells derived from pancreatic β cells. Exposure of MIN6 cells to cholesterol-induced apoptosis in time- and dose-dependent manner. Treatment with methyl-β-cyclodextrin that removes cholesterol from plasma membrane prevented the cells from cholesterol-induced apoptosis. Western blot analysis revealed that the levels of phosphorylated-p38 mitogen-activated protein kinase (P-p38 MAPK) and c-Jun N-terminal kinases (P-JNK) were significantly increased after the cholesterol loading, suggesting that the stress-activated protein kinase signaling was stimulated. A specific p38 inhibitor rescued MIN6 cells from cholesterol-induced apoptosis, while JNK inhibitor failed, suggesting the importance of activation of p38 MAPK signaling in response to cholesterol. The expression of Bip and CHOP, the endoplasmic reticulum (ER) stress markers, remained unaffected, indicating that the ER stress may not be involved in the cytotoxicity of cholesterol on the ΜΙΝ6 cells. The intracellular concentration of reactive oxygen species measured by use of 2',7'-dichlorofluorescin diacetate was significantly increased after cholesterol loading, demonstrating the induced apoptosis was mediated through oxidative stress. Addition of reduced form of glutathione in the medium rescued MIN6 cells from apoptosis induced by cholesterol loading. Taken together, these results demonstrate that the free cholesterol loading can induce apoptosis of MIN6 cells mediated by oxidative stress and the activation of p38 MAPK signaling.