A real-time PCR approach based on SPF10 primers and the INNO-LiPA HPV genotyping extra assay for the detection and typing of human papillomavirus

A highly sensitive SPF10 real-time PCR was developed to achieve simultaneous amplification and detection of the human papillomavirus (HPV) target. That way, LiPA analysis of the HPV-negative samples can be avoided, reducing workload and cost. Here, we describe in detail a SYBR Green I-based real-time PCR assay based on SPF10 primers using the LightCycler(®) 480 system to generate and detect HPV amplicons, which are compatible with the LiPA assay.

Longitudinal quantification of radical bursts during pulmonary ischaemia and reperfusion

OBJECTIVES

Pulmonary ischaemia-reperfusion injury (IRI) is associated with several life-threatening pulmonary disorders, and may severely compromise the outcome of lung transplantation. Highly reactive molecules such as superoxide, nitric oxide (NO) and peroxynitrite (ONOO(-)) are presumed to contribute to IRI pathogenesis, but this assumption is based on indirect measurements. We use electron spin resonance (ESR) to directly quantify free radical formation after pulmonary ischaemia and reperfusion.

METHODS

Five groups of 10 Swiss mice were subjected to left pulmonary hilum clamping for 1 h of ischaemia followed by 0, 1, 4 and 24 h of reperfusion or to sham thoracotomy alone as control procedure. In five mice per group, ESR was used to measure iron-diethyldithio-carbamate trihydrate-trapped NO in the lung. In the other group of 5, reactive oxygen species generation in the lung and in blood was quantified with ESR by detection of ascorbyl radical and CMH spin probe, respectively. Pulmonary ONOO(-) was monitored with nitrotyrosine Western blotting.

RESULTS

After 1 h of reperfusion, a pulmonary NO peak (14.69 ± 0.91 × 10(4) Arbitrary Units (A.U.). vs 1.84 ± 0.75 × 10(4) A.U. in sham; P < 0.001) coincided with a significant increase in nitrosated proteins (0.105 ± 0.015 A.U.) compared with sham (0.047 ± 0.006 A.U.); P < 0.005). Peripheral blood showed a significant free radical burst after 1 h of ischaemia (11 774 ± 728 A.U. vs 6660 ± 833 A.U. in sham; P < 0.001).

CONCLUSIONS

Longitudinal quantification of free radicals during IRI reveals the occurrence of two major radical bursts. The radical peak in peripheral blood after ischaemia may be related to systemic hypoxia. After 1 h of reperfusion, the lung tissue shows a significant increase of superoxide, NO and their reaction products, which are probably involved in IRI pathogenesis.

Comparison of SPF10 real-time PCR and conventional PCR in combination with the INNO-LiPA HPV Genotyping Extra assay for the detection and typing of human papillomavirus in cervical samples

The novel SPF10 real-time PCR assay allows the simultaneous amplification and detection of the HPV target. That way, LiPA analysis of the HPV-negative samples can be avoided, reducing workload and cost. This study aims to evaluate the performance of the SPF10 real-time PCR in combination with the LiPA assay for HPV detection and typing in cervical samples. Thirty-nine cervical samples were subjected to the SPF10 conventional PCR in combination with the LiPA assay. Subsequently, the SPF10 real-time PCR was performed to enable the comparison between the SPF10 conventional and the real-time PCR results. In case of discrepancy, the samples were subjected to the CLART HPV2 assay. As a result, 27 out of 39 samples were identified as HPV-positive by the SPF10 real-time PCR and were genotyped further by the LiPA assay. Twenty samples (74.1%) showed an absolute agreement between the conventional and real-time SPF10 PCR (concordant), three (11.1%) displayed additional or fewer types (compatible), two (7.4%) did not show any similarity between both assays (discordant) and the remaining two (7.4%) were LiPA-negative. The two assays showed an excellent strength of agreement for individual (κ=0.932) and multiple genotype detection (κ=0.834). In conclusion, the two SPF10 PCR methods are comparable. Therefore, the SPF10 real-time PCR with subsequent LiPA could be used for the detection and genotyping of HPV in cervical samples.

The TRPM6/EGF pathway is downregulated in a rat model of cisplatin nephrotoxicity

Cisplatin-induced hypomagnesemia is described in humans and rats, but the underlying mechanisms are still unclear. Recent studies have shown that epidermal growth factor (EGF) stimulates Mg²⁺ re-absorption in the distal convoluted tubule via the Mg²⁺ channel TRPM6. This study investigates the role of TRPM Mg²⁺ channels, claudines, and EGF in the Mg²⁺ homeostasis in a rat model of cisplatin-induced nephrotoxicity. Wistar rats were given 2.5 mg/kg cisplatin per week for 3 weeks and were euthanized 4 or 9 weeks after the first administration. The cisplatin treatment significantly increased the fractional excretion of Mg²⁺. Real-time RT-PCR and/or Western blots were performed to assess the renal expression TRPM6, TRPM7, claudin-16, claudin-19, EGF, EGF receptor (EGFR) and EGFR-pathway components. The renal mRNA expression of TRPM6 and EGF showed a significant decrease after cisplatin treatment, while the TRPM7, claudin-16 and EGFR expressions remained stable. The claudin-19 mRNA expression was significantly upregulated after cisplatin treatment. Western blotting confirmed the mRNA expression data for the claudins, but an showed upregulation of EGFR only at week 9. The role of the EGFR pathway, involving Pi3-AKT-Rac1, in cisplatin-induced nephropathy, could not be substantiated in further detail. This study shows that cisplatin treatment results in EGF and TRPM6 downregulation in the rat kidney, causing renal Mg²⁺ loss. Our results are in line with the hypothesis that EGF influences the renal expression or activation of TRPM6 and plays a significant role in Mg²⁺ loss in medication-induced nephropathy.

WITHDRAWN: A real-time PCR approach based on SPF10 primers and the INNO-LiPA HPV Genotyping Extra assay for the detection and typing of human papillomavirus

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Expression of renal distal tubule transporters TRPM6 and NCC in a rat model of cyclosporine nephrotoxicity and effect of EGF treatment

Renal magnesium (Mg2+) and sodium (Na+) loss are well-known side effects of cyclosporine (CsA) treatment in humans, but the underlying mechanisms still remain unclear. Recently, it was shown that epidermal growth factor (EGF) stimulates Mg2+ reabsorption in the distal convoluted tubule (DCT) via TRPM6 (Thébault S, Alexander RT, Tiel Groenestege WM, Hoenderop JG, Bindels RJ. J Am Soc Nephrol 20: 78–85, 2009). In the DCT, the final adjustment of renal sodium excretion is regulated by the thiazide-sensitive Na+-Cl− cotransporter (NCC), which is activated by the renin-angiotensin-aldosterone system (RAAS). The aim of this study was to gain more insight into the molecular mechanisms of CsA-induced hypomagnesemia and hyponatremia. Therefore, the renal expression of TRPM6, TRPM7, EGF, EGF receptor, claudin-16, claudin-19, and the NCC, and the effect of the RAAS on NCC expression, were analyzed in vivo in a rat model of CsA nephrotoxicity. Also, the effect of EGF administration on these parameters was studied. CsA significantly decreased the renal expression of TRPM6, TRPM7, NCC, and EGF, but not that of claudin-16 and claudin-19. Serum aldosterone was significantly lower in CsA-treated rats. In control rats treated with EGF, an increased renal expression of TRPM6 together with a decreased fractional excretion of Mg2+ (FE Mg2+) was demonstrated. EGF did not show this beneficial effect on TRPM6 and FE Mg2+ in CsA-treated rats. These data suggest that CsA treatment affects Mg2+ homeostasis via the downregulation of TRPM6 in the DCT. Furthermore, CsA downregulates the NCC in the DCT, associated with an inactivation of the RAAS, resulting in renal sodium loss.

Importance of suitable reference gene selection for quantitative real-time PCR: special reference to mouse myocardial infarction studies

BACKGROUND

Quantitative real-time PCR (qPCR) is a widely used technique for gene expression analysis. Its reliability is highly dependent upon selection of the appropriate reference genes for accurate gene expression normalization. In this study, we investigated the expression stability of 10 commonly used reference genes in a mouse myocardial infarction model.

METHODS & RESULTS

The expression stability of the 10 reference genes (Actb, B2m, Eef1a1, Gapdh, Hprt, Polr2a, Ppia, Rpl13a, Tbp, Tpt1) was analyzed using the geNorm software. Overall, the combination of Hprt, Rpl13a and Tpt1 was the most stable reference gene set in our experiments. Gapdh, Polr2a and Actb consistently showed the highest gene expression variability and the expression levels of Gapdh, Polr2a, Actb, B2m and Eef1a1 were found to be selectively up- or downregulated after myocardial infarction. We normalized the expression of Nppb and Vcam1, using different reference gene strategies and demonstrated that their induction after myocardial infarction was most clearly revealed with the optimal reference gene combination. However, the use of suboptimal reference gene combinations resulted in detrimental effects on gene expression levels and variability with a gradual loss of the expression differences and a significant reduction in statistical power.

CONCLUSIONS

Hprt, Rpl13a and Tpt1 are a set of stably expressed reference genes for accurate gene expression normalization in myocardial infarction studies in mice. We found that Gapdh, Polr2a and Actb display high expression variability in mouse myocardial infarction tissues and that loss of statistical power and increase in sample size are the evident consequences of choosing suboptimal combinations of reference genes. We furthermore caution against the use of Gapdh, Polr2a, Actb, B2m and Eef1a1 for gene expression normalization in myocardial infarction studies because of selective up- or downregulation after myocardial infarction, which could potentially lead to biased study outcomes.