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Background Torquetenovirus (TTV) viremia is emerging as a promising tool to assess functional immune competence, to predict posttransplant immune-related complications, and eventually to customize immunosuppression. Methods In this study, 327 blood samples were tested using two real-time PCR (rtPCR) assays both targeted to the untranslated region of the TTV genome. The first assay was an in-house rtPCR developed by our group, the second one was the recently marketed TTV R-GENE assay. Results In the validation study, the TTV R-GENE showed good performances in precision and reproducibility, and sensitivity as low as 12 TTV DNA copies/mL, like previously reported for the in-house rtPCR. The Bland-Altman analysis showed that the mean difference between the two methods was -0.3 log copies/mL. In the comparison study, 69% and 72% of samples were detected positive by rtPCR and TTV R-GENE, respectively (94% concordance, kappa = 0.88). Performances did not differ between the two rtPCRs by type of TTV group examined. When a newly-developed in-house digital droplet PCR was applied for TTV quantification and used as an alternative method of comparison on 94 samples, the results strongly correlated with those obtained by the two rtPCR methods (99% concordance). Conclusion In summary, all the molecular methods assayed are highly sensitive and accurate in quantitation of TTV DNA in blood samples.

Monitoring the human virome has been recently suggested as a promising and novel area of research for identifying new biomarkers which would help physicians in the management of transplant patients. Imbalance of the immune system in transplant recipients has a significant impact on replication of Torquetenovirus (TTV), the most representative and abundant virus of human virome. TTV kinetic was studied by real-time PCR in 280 liver or kidney transplant recipients who underwent different drug regimens to maintain immunosuppression. During one-year post-transplant follow-up, TTV viremia fluctuated irrespective of transplanted organ type but consistent with the immunosuppression regimen. TTV kinetic in patients who manifested cytomegalovirus (CMV) reactivation within the first four months post-transplant differed from that observed in patients who did not experience CMV complications. Importantly, plasma TTV load measured between day 0 and 10 post-transplant was significantly higher in CMV DNA positive than in CMV DNA negative patients. TTV viremia above 3.45 log DNA copies/ml within the first 10 days post-transplant correlates with higher propensity to CMV reactivation following transplantation. This study provides further evidence for using early post-transplant TTV viremia to predict CMV reactivation in liver or kidney transplant recipients.

It is well known that Mediterranean catchments are characterized by a complex hydrological behavior and strong non-linearities (Ye et al., 1998, Piñol et al., 1999). Therefore, modeling hydrology of a small Mediterranean catchment still represents a great challenge for modelers. To this end, the practical superiority of distributed or semi-distributed approaches over lumped ones remains an open question (see e.g. Loague and Freeze, 1985; Michaud and Sorooshian, 1994; Refsgaard and Knudsen, 1996; Loumagne et al., 1999; Zhang et al., 2003). In fact, a variety of earlier studies have inter-compared distributed versus lumped model simulations reaching opposite conclusions. With the present work, we tried to answer the following research question: Are observed non-linearities due to spatial heterogeneity or to non-linear mechanisms that should be taken into account in a model conceptual scheme? To address these issues the hydrological modeling of the Can Vila catchment (Vallcebre, Eastern Pyrenees, Spain) was carried out. Three hydrological models were considered: two lumped models called LU3 and LU4 (Medici et al., 2008), and a fully distributed model called TETIS (Francés et al., 2007). The TETIS model has the same conceptual schema as the LU3 model at cell-scale and the LU4 model¿s structure is based on the LU3 model, but it splits the aquifer storage in two tanks: shallow aquifer and deep aquifer. Percolation to the deep aquifer occurs only when soil water content exceeds a threshold value. So, the difference between the LU3 model and the TETIS model is the incorporation of the spatial heterogeneity and the difference between the LU3 model and the LU4 model is an additional strong non-linearity with the threshold which actives the deep percolation. The graphical comparison with the observations and the goodness of fit indexes employed showed that: (1) the LU3 model could not reproduce reasonably well the wet and dry period with the same set of parameters while (2) the LU4 and the TETIS model gave similar results and much better than the LU3 model¿s results. However, a multi-criteria analysis was done and the concept of Pareto Optimal (Bastidas, 1999) was employed to determine which model (LU4 or TETIS) was more suitable to represent the observed behavior of this small Mediterranean catchment. This analysis showed the higher capability and robustness of the distributed model to reproduce the complex hydrological behavior observed in this catchment.

A recent study evidenced by metyrapone test a central adrenal insufficiency (CAI) in 60% of Prader-Willi syndrome (PWS) children. These results were not confirmed in investigations with low [Low-Dose Tetracosactrin Stimulation Test (LDTST), 1 μg] or standard-dose tetracosactrin stimulation tests. We extended the research by LDTST in paediatric patients with PWS.Cross-sectional evaluation of adrenal stress response to LDTST in a PWS cohort of a tertiary care referral centre.Eighty-four children with PWS.Assessment of adrenal response by morning cortisol and ACTH dosage, and 1-μg tetracosactrin test. Response was considered appropriate when cortisol reached 500 nm; below this threshold, patients were submitted to a second test. Responses were correlated with the patients' clinical and molecular characteristics to assess genotype-phenotype correlation.Pathological cortisol peak responses to the LDTST were registered in 12 patients (14.3%) who had reduced basal (169.4 ± 83.3 nm) and stimulated (428.1 ± 69.6 nm) cortisol levels compared to patients with normal responses (367.1 ± 170.6 and 775.9 ± 191.3 nm, P0.001). Body mass index standard deviation score was negatively correlated with basal and peak cortisol levels (both P0.001), and the patients' ages (P0.001). In patients with deletion on chromosome 15, the cortisol peak was significantly lower than that in uniparental disomy (UPD) cases (P = 0.030). At multiple regression analysis, the predictors of peak response were basal cortisol, age, and UPD subclass (r(2) = 0.353, P0.001). Standard-dose (250 μg) tetracosactrin test confirmed CAI in 4/12 patients (4.8% of the cohort).Our results support the hypothesis that, albeit rare, CAI may be part of the PWS in childhood.

Gemycircularviruses (GemyCV) are a vast array of viruses belonging to the Genomoviridae family. Prevalence and pathogenesis in humans are still poorly understood. Different GemyCV species were investigated in 661 Italian subjects by species-specific PCRs. Only the GemyCV-C1c species was detected, with low prevalence and the highest rate in HIV immunosuppressed patients.