Junxia Zhang

Magnesium modulates the expression levels of calcification-associated factors to inhibit calcification in a time-dependent manner

Vascular calcification, a common complication in patients with chronic kidney disease, involves a variety of mechanisms associated with the regulation of calcification-associated factors. Previous clinical studies have indicated that magnesium is involved in the reduction of vascular calcification; however, the mechanism underlying this process remains unknown. The aim of the present study was to investigate the effects of magnesium on β-glycerophosphate (β-GP)-induced calcification and the underlying mechanisms. Primary rat vascular smooth muscle cells (VSMCs) were exposed to 10 mM β-GP in medium with or without the addition of 3 mM magnesium or 2-aminoethoxy-diphenylborate (2-APB; an inhibitor of magnesium transport), for a 14-day period. Calcium deposition and alkaline phosphatase (ALP) activity were measured by Alizarin red staining, quantification of calcium and enzyme-linked immunosorbent assay. The expression levels of core-binding factor α-1 (Cbfα1), matrix Gla protein (MGP) and osteopontin (OPN) were determined by reverse transcription-polymerase chain reaction or western blot analysis, following incubation for 0, 3, 6, 10 and 14 days with the different media. VSMC calcification and ALP activity was reduced significantly in the high-magnesium medium compared with the calcification medium, during the 14-day incubation. The magnesium-induced changes in the VSMCs included a β-GP-induced downregulation of Cbfα1 by day 3 of incubation, an effect that was gradually enhanced over the 14-day period. By contrast, magnesium produced notable increases in MGP and OPN expression levels, with an opposite pattern to that observed in the Cbfα1 expression levels. However, the addition of 2-APB appeared to inhibit the protective effect of magnesium on the VSMCs. Therefore, magnesium was able to effectively reduce β-GP-induced calcification in rat VSMCs by regulating the expression levels of calcification-associated factors in a time-dependent manner.

Single nucleotide polymorphisms in the mitochondrial displacement loop and age-at onset of renal cell carcinoma

The accumulation of single nucleotide polymorphisms (SNPs) in the displacement loop (D-loop) of mitochondrial DNA (mtDNA) has been described in various types of cancers, and their association with cancer risk and disease outcome has been extensively identified. In the present study, we investigated the association between age-at-onset and SNPs in the mitochondrial D-loop using a population-based series of renal cell carcinoma(RCC). The SNP sites of nucleotides 16293A/G were identified for their association with age-at-onset using the log-rank test. The age-at-onset of patients with the minor allele G genotype was significantly lower than that of patients with the A genotype at the 16293 site (p < 0.001). Genetic polymorphisms in the D-loop are predictive markers of age-at-onset in RCC patients. Accordingly, the analysis of genetic polymorphisms in the mitochondrial D-loop may help identify RCC patient subgroups at high risk of early onset.

Single nucleotide polymorphisms in the D-loop region of mitochondrial DNA is associated with renal cell carcinoma outcome.

Abstract Accumulation of single nucleotide polymorphisms (SNPs) in the displacement loop (D-loop) of mitochondrial DNA (mtDNA) has been described in various types of cancers and might be associated with cancer risk and disease outcome. We identified 14 SNPs with a frequency higher than 5% and 5 SNPs associated with the risk of renal cell carcinoma (RCC) in a case–control study previously. In the present study, we assessed the relationship of these SNPs and the outcome of RCC patients, a SNP of 262C/T was identified by the log-rank test for statistically significant prediction of RCC survival. In an overall multivariate analysis, allele 262 was identified as an independent predictor of RCC outcome. The length of survival of patients with 262T was significantly shorter than that of patients with allele 262C (relative risk, 2.136, 95%CI, 1.863–2.449; p = 0.000). The analysis of genetic polymorphisms in the mitochondrial D-loop can help identify patients subgroup at high risk of a poor disease outcome.

Alteration of Type I Collagen in the Radial Artery of Patients With End-Stage Renal Disease

Background:Cardiovascular disease is the leading cause of death in chronic kidney disease. Extracellular matrix remodeling is implicated in atherosclerosis development. This study investigated the effects and possible mechanism of type I collagen expression on radial artery elasticity in patients with end-stage renal disease (ESRD). Methods:Sixty-five patients receiving forearm arteriovenous fistula in the Fourth Hospital of Hebei Medical University from January 2010 to December 2012 were enrolled in the study. The echo-tracking technique was used to measure radial artery 1-point pulse wave velocity (PWV&bgr;), and immunohistochemical staining was used to detect the expression of type I collagen and transcription factor CBFA1, a marker for calcification, in the radial artery. Uremic serum and serum from healthy volunteers of different concentrations were then used to treat the rat aortic vascular smooth muscle cells (VSMCs), reverse transcription polymerase chain reaction (PCR) was used to measure COL1A1 and CBFA1 transcription and a Western blot was performed to detect type I collagen expression in the rat aortic VSMCs. Results:In patients with ESRD, increased COL1A1 expression was an independent risk factor for radial artery PWV&bgr; (P < 0.05) and was positively associated with that of CBFA1 (r = 0.573, P < 0.001). In the rat aortic VSMCs, serum from patients with ESRD upregulated COL1A1 and CBFA1 transcription as well as type I collagen expression in a concentration-dependent manner (P < 0.05). Conclusions:Type I collagen expression is an essential factor for radial artery elasticity dysfunction in patients with ESRD. Uremic toxins apparently induced a phenotypic transition of the rat aortic VSMCs, leading to increased type I collagen secretion and subsequent extracellular matrix remodeling.

Effects of extracellular acid stimulation on rat vascular smooth muscle cell in Gas6/Axl or PI3K/Akt signaling pathway.

ABSTRACT Recent studies have indicated that extracellular acid stimulation inhibited the calcification of vascular smooth muscle cells (VSMCs). Cell apoptosis played an important role in the occurrence and development of vascular calcification. We further explored the effects of Gas6/Axl or PI3K/Akt signaling pathway on the inhibition of rat VSMCs calcification in response to extracellular acid stimulation. Our study demonstrated that a high concentration of phosphorus induced apoptosis and calcification of VSMCs, decreased expression of Axl, and reduced phosphorylation of Akt. Stimulation of extracellular acid counteracted the effects as above by increasing the expression of Axl and Akt phosphorylation and decreasing the expression of activated Caspase3, which thereby decreased cell apoptosis and calcification. Moreover, the effects can be attenuated by PI3K inhibitor. Our study proved that extracellular acid stimulation played a vital role in the inhibition of rat VSMCs calcification and apoptosis in Gas6/Axl or PI3K/Akt signaling pathway.

Single nucleotide polymorphisms in the D-loop region of mitochondrial DNA is associated with the kidney survival time in chronic kidney disease patients

Abstract Background: The mitochondrial displacement loop (D-loop) is known to accumulate mutations and SNPs at a higher frequency than other regions of mitochondrial DNA (mtDNA). We had identified chronic kidney disease (CKD) risk-associated SNPs in the D-loop of CKD patients previously. In this study, we investigated the association of SNPs in the D-loop of mtDNA with the kidney survival of CKD. Methods: The D-loop region of mtDNA was sequenced for 119 CKD patients from the inpatient of the Fourth Hospital of Hebei Medical University. The Kaplan–Meier method was used to identify disease outcome-associated SNPs in the D-loop of CKD patients. The Cox proportional hazards model was used to identify risk factors for the kidney survival of CKD. Results: In the present study, we identified 20 SNPs with a frequency higher than 5% and assessed the relationship of these SNPs with kidney survival time in CKD patients, a SNP of 146 was identified by log-rank test for statistically significant prediction of the kidney survival time. In an overall multivariate analysis, allele 146 was identified as an independent predictor of kidney survival time in CKD patients. The survival time of kidney in the CKD patients with 146C was significantly shorter than that of kidney in CKD patients with 146T (relative risk, 2.336; 95% CI, 1.319–3.923; p = 0.001). Conclusion: SNPs in the D-loop can predict the kidney survival of CKD patients. Analysis of genetic polymorphisms in the mitochondrial D-loop can help to identify CKD patient subgroup at high risk of a poor disease outcome.

Association of sequence polymorphism in the mitochondrial D-loop with chronic kidney disease

Abstract Background: The mitochondrial displacement loop (D-loop) is known to accumulate mutations and single nucleotide polymorphisms (SNPs) at a higher frequency than other regions of mitochondrial DNA (mtDNA). Methods: This is a case–control study. We sequenced SNPs in the D-loop of mtDNA and investigated their association with the risk of chronic kidney disease (CKD). Results: A total of 144 SNPs referring to the positions of the Revised Cambridge Reference Sequence (rCRS) for mitochondrial genome were identified in a case–control study. The minor alleles of nucleotides 73G, 146C, 150T, 194T, 195C and 310C were associated with an increased risk for CKD patients. Conclusion: Analysis of genetic polymorphisms in the mitochondrial D-loop can help identify the people who are at a high risk of developing chronic kidney disease. These SNPs can be considered as potential predictors for CKD.

High EphA2 protein expression in renal cell carcinoma is associated with a poor disease outcome

The receptor tyrosine kinase, ephrin type-A receptor 2 (EphA2), is normally expressed at sites of cell-to-cell contact in adult epithelial tissues, however, recent studies have shown that it is also overexpressed in various types of epithelial carcinomas, with the greatest level of EphA2 expression observed in metastatic lesions. In the present study, the association between the expression of EphA2 and the outcome of RCC patients was assessed. The high expression level of EphA2 was identified by log-rank test for a statistically significant prediction of the RCC outcome. In an overall multivariate analysis, the high expression level of EphA2 was identified as an independent predictor of RCC outcome. The length of survival of the patients with high EphA2 expression was shorter than that of the patients with a low level of expression (relative risk, 2.304; 95% CI, 1.102–4.818; P=0.027). The analysis of the expression levels of EphA2 in tumor tissues may aid in the identification of the patient subgroup that are at a high risk of a poor disease outcome.

The 9-bp deletion at position 8272 in region V of mitochondrial DNA is associated with renal cell carcinoma outcome.

Abstract Mitochondrial DNA (mtDNA) is considered a mutation hotspot in various types of tumors, and mitochondrial DNA microsatellite instability (mtMSI) is associated with various cancers. We had previously identified cancer risk-associated MSIs in the D-loop region of mtDNA in renal cell carcinoma (RCC) patients. In the present study, we further investigated the association of MSIs in the non-D-loop region of mtDNA with cancer risk and outcome of RCC. Six microsatellite loci (5892, 8272, 8280, 8281, 8289, 9777) in the non-D-loop of mtDNA were assessed. The CCCCCTCTA at position 8272 was associated with cancer outcome in an overall multivariate analysis (relative risk, 1.599; 95%CI, 1.365–1.872; p < 0.001). mtMSI at position 8272 can therefore be used as an independent prognostic marker for RCC patients.

Analysis of a Single Hemodialysis on Phosphate Removal of the Internal Fistula Patients by Mathematical and Statistical Methods

Chronic kidney disease related mineral and bone disease (CKD-MBD) is a worldwide challenge in hemodialysis patients. In china, the number of dialysis patients is growing but few data are available about their bone disorders. In the current study, we aimed to evaluate the effect of clinical factors on the serum phosphorus clearance in the 80 maintenance hemodialysis (MHD) patients. Six clinical factors were identified for their association with the serum phosphorus clearance using the analysis of Spearmans single linear correlation, including predialysis serum phosphate level, CRR, membrane surface area of the dialyzer, effective blood flow rate, the blood chamber volume, and hematocrit. In an overall multivariate analysis, pre-P, CRR, membrane SA, and Qb were identified as independent risk factors associated with the serum phosphorus clearance. In conclusion, HD could effectively clear serum phosphorus. The analysis of CRR might help to estimate serum phosphorus reduction ratio.