Mareike Franke

Mutations in NEK8 link multiple organ dysplasia with altered Hippo signalling and increased c-MYC expression

Mutations affecting the integrity and function of cilia have been identified in various genes over the last decade accounting for a group of diseases called ciliopathies. Ciliopathies display a broad spectrum of phenotypes ranging from mild manifestations to lethal combinations of multiple severe symptoms and most of them share cystic kidneys as a common feature. Our starting point was a consanguineous pedigree with three affected fetuses showing an early embryonic phenotype with enlarged cystic kidneys, liver and pancreas and developmental heart disease. By genome-wide linkage analysis, we mapped the disease locus to chromosome 17q11 and identified a homozygous nonsense mutation in NEK8/NPHP9 that encodes a kinase involved in ciliary dynamics and cell cycle progression. Missense mutations in NEK8/NPHP9 have been identified in juvenile cystic kidney jck mice and in patients suffering from nephronophthisis (NPH), an autosomal-recessive cystic kidney disease. This work confirmed a complete loss of NEK8 expression in the affected fetuses due to nonsense-mediated decay. In cultured fibroblasts derived from these fetuses, the expression of prominent polycystic kidney disease genes (PKD1 and PKD2) was decreased, whereas the oncogene c-MYC was upregulated, providing potential explanations for the observed renal phenotype. We furthermore linked NEK8 with NPHP3, another NPH protein known to cause a very similar phenotype in case of null mutations. Both proteins interact and activate the Hippo effector TAZ. Taken together, our study demonstrates that NEK8 is essential for organ development and that the complete loss of NEK8 perturbs multiple signalling pathways resulting in a severe early embryonic phenotype.

Assessment of Tumor Size Reduction Improves Outcome Prediction of Positron Emission Tomography/Computed Tomography After Chemotherapy in Advanced-Stage Hodgkin Lymphoma

PURPOSE Positron emission tomography (PET) after chemotherapy can guide consolidating radiotherapy in advanced-stage Hodgkin lymphoma (HL). This analysis aims to improve outcome prediction by integrating additional criteria derived by computed tomography (CT). PATIENTS AND METHODS The analysis set consisted of 739 patients with residues≥2.5 cm after chemotherapy from a total of 2,126 patients treated in the HD15 trial (HD15 for advanced stage Hodgkins disease: Quality assurance protocol for reduction of toxicity and the prognostic relevance of fluorodeoxyglucose-positron-emission tomography [FDG-PET] in the first-line treatment of advanced-stage Hodgkins disease) performed by the German Hodgkin Study Group. A central panel performed image analysis and interpretation of CT scans before and after chemotherapy as well as PET scans after chemotherapy. Prognosis was evaluated by using progression-free survival (PFS); groups were compared with the log-rank test. Potential prognostic factors were investigated by using receiver operating characteristic analysis and logistic regression. RESULTS In all, 548 (74%) of 739 patients had PET-negative residues after chemotherapy; these patients did not receive additional radiotherapy and showed a 4-year PFS of 91.5%. The 191 PET-positive patients (26%) receiving additional radiotherapy had a 4-year PFS of 86.1% (P=.022). CT alone did not allow further separation of patients in partial remission by risk of recurrence (P=.9). In the subgroup of the 54 PET-positive patients with a relative reduction of less than 40%, the risk of progression or relapse within the first year was 23.1% compared with 5.3% for patients with a larger reduction (difference, 17.9%; 95% CI, 5.8% to 30%). CONCLUSION Patients with HL who have PET-positive residual disease after chemotherapy and poor tumor shrinkage are at high risk of progression or relapse.

Ultrasound-Guided Percutaneous Renal Biopsy in 295 Children and Adolescents: Role of Ultrasound and Analysis of Complications

Introduction Percutaneous renal biopsy (PRB) is a decisive diagnostic procedure for children and adolescents with renal diseases. Aim of this study was to evaluate retrospectively the complication rates of percutaneous kidney biopsies and their therapeutic consequences to assess the role of ultrasound-guidance including Doppler ultrasound examinations in preparation, execution and follow-up care and to present a recommended protocol. Patients and Methods Institutional review board approved this retrospective study; informed consent was waived. Between 1997 and 2011 a total of 438 ultrasound-guided biopsies were performed in 295 patients, 169 of the biopsies were performed on kidney transplants. Average age of patients was 10.2+/−5.2 years (range of 15 days until age of 23). Before and post biopsy ultrasound examination including Doppler examination was carried out. Biopsy itself was ultrasound monitored. Complications were analysed with regard to age of patient, kidney transplants, year of occurrence, number of punctures, performing physician and time interval of occurrence to develop an optimized protocol for ultrasound-guidance. Results In 99% of cases successful PRB were performed, i.e. enough kidney parenchyma for histological analysis was obtained. No lethal or major complication that required surgical intervention occurred. Eighteen relevant complications were observed (complication rate: 4.1%). Except in one case in which additional MRI diagnostic was necessary, ultrasound examination after 4 hours post biopsy or even earlier when symptoms occurred, was able to detect complications and determine indications for intervention. Conclusion Ultrasound-guided PRB is an established and effective method in children and adolescents, but shows a certain rate of complications and therefore should not be indicated without diligence. Ultrasound including Doppler ultrasound is a valuable tool in preparation, guidance of biopsy, detection of complications and in follow-up care. Ultrasound examinations (including Doppler) pre-, during and 4 hours post kidney biopsy and, depending from case, a few days until weeks after biopsy is recommended.

An approach to cystic kidney diseases: the clinician's view

Advances in molecular genetics have led to the identification of more than 70 different genes involved in the development of cystic kidney diseases. Most of these diseases are rare, and interpreting the resultant plethora of disease-causing mutations requires a methodical and meticulous approach to differential diagnosis. In this Review we discuss a clinical approach to the diagnosis of cystic kidney diseases in adults, for use by nephrologists. This approach is based upon a thorough clinical evaluation, which considers both kidney phenotype and extrarenal manifestations of the underlying disorder, in combination with genetic testing in selected patients. In our view, cystic kidney disease can (in the majority of patients) be reliably classified on the basis of clinical findings. We therefore propose that defining clinical situations to precipitate the initiation of genetic testing is mandatory and cost-effective. New techniques such as next-generation sequencing will facilitate the diagnosis of cystic kidney diseases in the future, increasing diagnostic safety in a subset of patients. In renal tumour syndromes, genetic testing is warranted.

Computed Tomography Volumetry in Preoperative Living Kidney Donor Assessment for Prediction of Split Renal Function.

Background Transplant centers commonly evaluate split renal function (SRF) with Tc-99m-mercapto-acetyltriglycin (MAG3) scintigraphy in living kidney donation. Alternatively, the kidney volume can be measured based on predonation CT scans. The aim of this study was to identify the most accurate CT volumetry technique for SRF and the prediction of postdonation kidney function (PDKF). Methods Three CT volumetry techniques (modified ellipsoid volume [MELV], smart region of interest [ROI] volume, renal cortex volume [RCV]) were performed in 101 living kidney donors. Preoperation CT volumetric SRF was determined and compared with MAG3-SRF, postoperation donor kidney function, and graft function. Results The correlation between donors predonation total kidney volume and predonation kidney function was the highest for RCV (0.58 with creatine clearance, 0.54 with estimated glomerular filtration rate-Cockcroft-Gault). The predonation volume of the preserved kidney was (ROI, MELV, RCV) 148.0 ± 29.1 cm3, 151.2 ± 35.4 and 93.9 ± 25.2 (P < 0.005 MELV vs RCV and ROI vs RCV). Bland-Altman analysis showed agreement between CT volumetry SRF and MAG3-SRF (bias, 95% limits of agreement: ROI vs MAG3 0.4%, −7.7% to 8.6%; MELV vs MAG3 0.4%, −8.9% to 9.7%; RCV vs MAG3 0.8%, −9.1% to 10.7%). The correlation between predonation CT volumetric SRF of the preserved kidney and PDKF at day 3 was r = 0.85 to 0.88, between MAG3-SRF and PDKF (r = 0.84). The difference of predonation SRF between preserved and donated kidney was the lowest for ROI and RCV (median, 3% and 4%; 95th percentile, 9% and 13%). Conclusions Overall renal cortex volumetry seems to be the most accurate technique for the evaluation of predonation SRF and allows a reliable prediction of donors PDKF.

Magnetic resonance T2 mapping and diffusion-weighted imaging for early detection of cystogenesis and response to therapy in a mouse model of polycystic kidney disease

Polycystic kidney disease (PKD) is among the leading causes of end-stage renal disease. Increasing evidence exists that molecular therapeutic strategies targeted to cyst formation and growth might be more efficacious in early disease stages, highlighting the growing need for sensitive biomarkers. Here we apply quantitative magnetic resonance imaging techniques of T2 mapping and diffusion-weighted imaging in the jck mouse model for PKD using a clinical 3.0 T scanner. We tested whether kidney T2 values and the apparent diffusion coefficient (ADC) are superior to anatomical imaging parameters in the detection of early cystogenesis, as shown on macro- and histopathology. We also tested whether kidney T2 values and ADC have the potential to monitor early treatment effects of therapy with the V2 receptor antagonist Mozavaptane. Kidney T2 values and to a lesser degree ADC were found to be highly sensitive markers of early cystogenesis and superior to anatomical-based imaging parameters. Furthermore, kidney T2 values exhibited a nearly perfect correlation to the histological cystic index, allowing a clear separation of the two mouse genotypes. Additionally, kidney T2 values and ADC were able to monitor early treatment effects in the jck mouse model in a proof-of-principle experiment. Thus, given the superiority of kidney T2 values and ADC over anatomical-based imaging in mice, further studies are needed to evaluate the translational impact of these techniques in patients with PKD.

Massive Air Embolism After Lung Biopsy

A 69-year-old man presented with pneumogenic sepsis. A chest radiograph showed bilateral extensive infiltrates that did not respond to broad-spectrum antibiotic treatment. Progressive respiratory failure necessitated invasive mechanical ventilation (bilevel positive airway pressure, 0.5 inspiratory oxygen saturation; peak inspiratory pressure, 24 cm H2O; positive end-expiratory pressure, 8 cm H2O). Chest computed tomography (CT) revealed inflammatory infiltrates with caverns and bilateral pleural effusions. Blood and bronchoalveolar cultures remained sterile. Therefore, computed tomography-guided lung biopsy was performed with an 18-gauge core needle with the patient in prone position (Figure, A). A control computed tomography scan (Figure, B) revealed massive systemic air embolism. Shortly thereafter, the patient developed cardiorespiratory failure. Cardiopulmonary resuscitation remained unsuccessful. Figure. A , Computed tomography-guided lung biopsy of infiltrates was performed with an 18-gauge needle and the patient in prone position. B , Air embolism after lung biopsy involving intercostal arteries (arrow), coronary arteries (arrowheads), and the aorta (white asterisk). Percutaneous computed tomography-guided lung biopsy is a frequently performed procedure for histological and microbiological analyses of pulmonary …

Implantation of venous access devices under local anesthesia: patients’ satisfaction with oral lorazepam

Objective The aim of the study reported here was to evaluate patients’ satisfaction with implantation of venous access devices under local anesthesia (LA) with and without additional oral sedation. Materials and methods A total of 77 patients were enrolled in the prospective descriptive study over a period of 6 months. Subcutaneous implantable venous access devices through the subclavian vein were routinely implanted under LA. Patients were offered an additional oral sedative (lorazepam) before each procedure. The level of anxiety/tension, the intensity of pain, and patients’ satisfaction were evaluated before and immediately after the procedure using a visual analog scale (ranging from 0 to 10) with a standardized questionnaire. Results Patients’ satisfaction with the procedure was high (mean: 1.3±2.0) with no significant difference between the group with premedication and the group with LA alone (P=0.54). However, seven out of 30 patients (23.3%) in the group that received premedication would not undergo the same procedure without general anesthesia. There was no significant influence of lorazepam on the intensity of pain (P=0.88). In 12 out of 30 patients (40%) in the premedication group, the level of tension was higher than 5 on the visual analog scale during the procedure. In 21 out of 77 patients (27.3%), the estimate of the level of tension differed between the interventionist and the patient by 3 or more points in 21 out of 77 patients (27.3%). Conclusion Overall patient satisfaction is high for implantation of venous access devices under LA. A combination of LA with lorazepam administered orally might not be adequate for patients with a high level of anxiety and tension. The level of tension is often underestimated by the interventionist. Pre-procedural standardized questionnaires could be used to identify patients for whom a gradual approach of individualized sedation may be more effective.

Targeted deletion of the AAA-ATPase Ruvbl1 in mice disrupts ciliary integrity and causes renal disease and hydrocephalus

Ciliopathies comprise a large number of hereditary human diseases and syndromes caused by mutations resulting in dysfunction of either primary or motile cilia. Both types of cilia share a similar architecture. While primary cilia are present on most cell types, expression of motile cilia is limited to specialized tissues utilizing ciliary motility. We characterized protein complexes of ciliopathy proteins and identified the conserved AAA-ATPase Ruvbl1 as a common novel component. Here, we demonstrate that Ruvbl1 is crucial for the development and maintenance of renal tubular epithelium in mice: both constitutive and inducible deletion in tubular epithelial cells result in renal failure with tubular dilatations and fewer ciliated cells. Moreover, inducible deletion of Ruvbl1 in cells carrying motile cilia results in hydrocephalus, suggesting functional relevance in both primary and motile cilia. Cilia of Ruvbl1-negative cells lack crucial proteins, consistent with the concept of Ruvbl1-dependent cytoplasmic pre-assembly of ciliary protein complexes.Cell cilia: Protein crucial for function identifiedA protein involved in building and maintaining thin protrusions from cell surfaces called cilia is implicated in “ciliopathies”, diseases in which ciliary function is disrupted. These include polycystic kidney disease and disorders collectively known as ciliary dyskinesias. “Primary cilia” perform sensory functions, detecting external chemical and physical signals and initiating responses within cells. In addition, “motile cilia” beat rhythmically to move fluids surrounding cells. Researchers in Germany and the Netherlands, led by Bernhard Schermer and Max C. Liebau at the University of Cologne, studied a protein called Ruvbl1, known to interact with DNA and other proteins. The researchers found it is crucial for the functioning of both types of cilia. Deleting the gene for Ruvbl1 in mice caused kidney failure and a build-up of fluid in the brain known as hydrocephalus. The research could help understand and ultimately treat ciliopathies.

Characterization of a splice-site mutation in the tumor suppressor gene FLCN associated with renal cancer

BackgroundRenal cell carcinoma is among the most prevalent malignancies. It is generally sporadic. However, genetic studies of rare familial forms have led to the identification of mutations in causative genes such as VHL and FLCN. Mutations in the FLCN gene are the cause of Birt-Hogg-Dubé syndrome, a rare tumor syndrome which is characterized by the combination of renal cell carcinoma, pneumothorax and skin tumors.MethodsUsing Sanger sequencing we identify a heterozygous splice-site mutation in FLCN in lymphocyte DNA of a patient suffering from renal cell carcinoma. Furthermore, both tumor DNA and DNA from a metastasis are analyzed regarding this mutation. The pathogenic effect of the sequence alteration is confirmed by minigene assays and the biochemical consequences on the protein are examined using TALEN-mediated transgenesis in cultured cells.ResultsHere we describe an FLCN mutation in a 55-year-old patient who presented himself with progressive weight loss, bilateral kidney cysts and renal tumors. He and members of his family had a history of recurrent pneumothorax during the last few decades. Histology after tumor nephrectomy showed a mixed kidney cancer consisting of elements of a chromophobe renal cell carcinoma and dedifferentiated small cell carcinoma component. Subsequent FLCN sequencing identified an intronic c.1177-5_-3delCTC alteration that most likely affected the correct splicing of exon 11 of the FLCN gene. We demonstrate skipping of exon 11 to be the consequence of this mutation leading to a shift in the reading frame and the insertion of a premature stop codon. Interestingly, the truncated protein was still expressed both in cell culture and in tumor tissue, though it was strongly destabilized and its subcellular localization differed from wild-type FLCN. Both, altered protein stability and subcellular localization could be partly reversed by blocking proteasomal and lysosomal degradation.ConclusionsIdentification of disease-causing mutations in BHD syndrome requires the analysis of intronic sequences. However, biochemical validation of the consecutive alterations of the resulting protein is especially important in these cases. Functional characterization of the disease-causing mutations in BHD syndrome may guide further research for the development of novel diagnostic and therapeutic strategies.