Early loss of peritubular capillaries after kidney transplantation

Inflammation, interstitial fibrosis (IF), and tubular atrophy (TA) precede chronic transplant dysfunction, which is a major cause of renal allograft loss. There is an association between IF/TA and loss of peritubular capillaries (PTCs) in advanced renal disease, but whether PTC loss occurs in an early stage of chronic transplant dysfunction is unknown. Here, we studied PTC number, IF/TA, inflammation, and renal function in 48 patients who underwent protocol biopsies. Compared with before transplantation, there was a statistically significant loss of PTCs by 3 months after transplantation. Fewer PTCs in the 3-month biopsy correlated with high IF/TA and inflammation scores and predicted lower renal function at 1 year. Predictors of PTC loss during the first 3 months after transplantation included donor type, rejection, donor age, and the number of PTCs at the time of implantation. In conclusion, PTC loss occurs during the first 3 months after renal transplantation, associates with increased IF and TA, and predicts reduced renal function.     

Therapeutic drug monitoring of tacrolimus with the dried blood spot method

In a preliminary investigation an assay for tacrolimus based on fingerprick sampling and consecutive application as a blood spot on sampling paper has been developed. The dried blood spot was analysed by HPLC-tandem mass spectrometry. The validated range was 1-30 microg/l. Intra- and inter-assay variability for precision and accuracy was <7.5% and 15%, respectively. Tacrolimus concentrations of 24 stable out patients were compared after both blood spot sampling and conventional venous sampling. Method agreement was investigated with the methods of Passing and Bablok and Bland Altman and proved suitable for clinical use. The dried blood spot method for tacrolimus seems promising for patient monitoring.     

Evaluation of limited sampling strategies for tacrolimus

Objective In literature, a great diversity of limited sampling strategies (LSS) have been recommended for tacrolimus monitoring, however proper validation of these strategies to accurately predict the area under the time concentration curve (AUC_0–12) is limited. The aim of this study was to determine whether these LSS might be useful for AUC prediction of other patient populations. Methods The LSS from literature studied were based on regression equations or on Bayesian fitting using MWPHARM 3.50 (Mediware, Groningen, the Netherlands). The performance was evaluated on 24 of these LSS in our population of 37 renal transplant patients with known AUCs. The results were also compared with the predictability of the regression equation based on the trough concentrations C₀ and C₁₂ of these 37 patients. Criterion was an absolute prediction error (APE) that differed less than 15% from the complete AUC_0–12 calculated by the trapezoidal rule. Results Thirteen of the 18 (72%) LSS based on regression analysis were capable of predicting at least 90% of the 37 individual AUC_0–12 within an APE of 15%. Additionally, all but three LSS examined gave a better prediction of the complete AUC_0–12 in comparison with the trough concentrations C₀ or C₁₂ (mean 62%). All six LSS based on Bayesian fitting predicted <90% of the 37 complete AUC_0–12 correctly (mean 67%). Conclusions The present study indicated that implementation of LSS based on regression analysis could produce satisfactory predictions although careful evaluation is necessary.     

Intra-observer variability in APACHE II scoring

Although the APACHE II score is the most widely used scoring system in intensive care units worldwide, its reliability and variability have not been extensively studied. Differences in case-mix may complicate comparison and interpretation of results. We hypothesised that a degree of variability might be inherent to use of the APACHE II scoring system, and decided to assess intra-observer variability in APACHE II scoring as a potential indicator of inherent score variability. APACHE II scores were assessed twice from the charts of 11 patients by 14 physicians, with a time interval of 4 (range 3.5-4.5) months between the two assessments. Intra-observer was found to be approximately 15%. These findings are in agreement with previous observations regarding inter-observer variability in APACHE II scoring, and strongly suggest that there is an inherent score variability of about 15%.     

HCN4 Mutations in Multiple Families With Bradycardia and Left Ventricular Noncompaction Cardiomyopathy

Background

Familial forms of primary sinus bradycardia have sometimes been attributed to mutations in HCN4, SCN5A, and ANK2. In these studies, no structural cardiac alterations were reported in mutation carriers. However, a cluster of reports in the literature describe patients presenting with sinus bradycardia in association with left ventricular noncompaction cardiomyopathy (LVNC), pointing to a shared genetic cause.

Objectives

This study sought to identify the genetic defect underlying the combined clinical presentation of bradycardia and LVNC, hypothesizing that these 2 clinical abnormalities have a common genetic cause.

Methods

Exome sequencing was carried out in 2 cousins from the index family that were affected by the combined bradycardia–LVNC phenotype; shared variants thus identified were subsequently overlaid with the chromosomal regions shared among 5 affected family members that were identified using single nucleotide polymorphism array analysis.

Results

The combined linkage analysis and exome sequencing in the index family identified 11 novel variants shared among the 2 affected cousins. One of these, p.Gly482Arg in HCN4, segregated with the combined bradycardia and LVNC phenotype in the entire family. Subsequent screening of HCN4 in 3 additional families with the same clinical combination of bradycardia and LVNC identified HCN4 mutations in each. In electrophysiological studies, all found HCN4 mutations showed a more negative voltage dependence of activation, consistent with the observed bradycardia.

Conclusions

Although mutations in HCN4 have been previously linked to bradycardia, our study provides the first evidence to our knowledge that mutations in this ion channel gene also may be associated with structural abnormalities of the myocardium.     

Differential effects of donor‐specific HLA antibodies in living versus deceased donor transplant

The presence of donor‐specific anti‐HLA antibodies (DSAs) is associated with increased risk of graft failure after kidney transplant. We hypothesized that DSAs against HLA class I, class II, or both classes indicate a different risk for graft loss between deceased and living donor transplant. In this study, we investigated the impact of pretransplant DSAs, by using single antigen bead assays, on long‐term graft survival in 3237 deceased and 1487 living donor kidney transplants with a negative complement‐dependent crossmatch. In living donor transplants, we found a limited effect on graft survival of DSAs against class I or II antigens after transplant. Class I and II DSAs combined resulted in decreased 10‐year graft survival (84% to 75%). In contrast, after deceased donor transplant, patients with class I or class II DSAs had a 10‐year graft survival of 59% and 60%, respectively, both significantly lower than the survival for patients without DSAs (76%). The combination of class I and II DSAs resulted in a 10‐year survival of 54% in deceased donor transplants. In conclusion, class I and II DSAs are a clear risk factor for graft loss in deceased donor transplants, while in living donor transplants, class I and II DSAs seem to be associated with an increased risk for graft failure, but this could not be assessed due to their low prevalence.     

Early release of high mobility group box nuclear protein 1 after severe trauma in humans: role of injury severity and tissue hypoperfusion

Introduction  

High mobility group box nuclear protein 1 (HMGB1) is a DNA nuclear binding protein that has recently been shown to be an early trigger of sterile inflammation in animal models of trauma-hemorrhage via the activation of the Toll-like-receptor 4 (TLR4) and the receptor for the advanced glycation endproducts (RAGE). However, whether HMGB1 is released early after trauma hemorrhage in humans and is associated with the development of an inflammatory response and coagulopathy is not known and therefore constitutes the aim of the present study.