Alexandra Kelp

A Novel Transgenic Rat Model for Spinocerebellar Ataxia Type 17 Recapitulates Neuropathological Changes and Supplies In Vivo Imaging Biomarkers

Spinocerebellar ataxia 17 (SCA17) is an autosomal-dominant, late-onset neurodegenerative disorder caused by an expanded polyglutamine (polyQ) repeat in the TATA-box-binding protein (TBP). To further investigate this devastating disease, we sought to create a first transgenic rat model for SCA17 that carries a full human cDNA fragment of the TBP gene with 64 CAA/CAG repeats (TBPQ64). In line with previous observations in mouse models for SCA17, TBPQ64 rats show a severe neurological phenotype including ataxia, impairment of postural reflexes, and hyperactivity in early stages followed by reduced activity, loss of body weight, and early death. Neuropathologically, the severe phenotype of SCA17 rats was associated with neuronal loss, particularly in the cerebellum. Degeneration of Purkinje, basket, and stellate cells, changes in the morphology of the dendrites, nuclear TBP-positive immunoreactivity, and axonal torpedos were readily found by light and electron microscopy. While some of these changes are well recapitulated in existing mouse models for SCA17, we provide evidence that some crucial characteristics of SCA17 are better mirrored in TBPQ64 rats. Thus, this SCA17 model represents a valuable tool to pursue experimentation and therapeutic approaches that may be difficult or impossible to perform with SCA17 transgenic mice. We show for the first time positron emission tomography (PET) and diffusion tensor imaging (DTI) data of a SCA animal model that replicate recent PET studies in human SCA17 patients. Our results also confirm that DTI are potentially useful correlates of neuropathological changes in TBPQ64 rats and raise hope that DTI imaging could provide a biomarker for SCA17 patients.

High definition urethral pressure profilometry: Evaluating a novel microtip catheter

Urethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI). SUI is a significant medical, social, and economic problem, affecting about 12.5% of the population. A novel microtip catheter was developed for UPP featuring an inclination sensor and higher angular resolution compared to systems in clinical use today. Therewith, the location of each measured pressure sample can be determined and the spatial pressure distribution inside the urethra reconstructed. In order to assess the performance and plausibility of data from the microtip catheter, we compare it to data from a double balloon air charged system.

Signal processing in urodynamics: towards high definition urethral pressure profilometry

BackgroundUrethral pressure profilometry (UPP) is used in the diagnosis of stress urinary incontinence (SUI) which is a significant medical, social, and economic problem. Low spatial pressure resolution, common occurrence of artifacts, and uncertainties in data location limit the diagnostic value of UPP. To overcome these limitations, high definition urethral pressure profilometry (HD-UPP) combining enhanced UPP hardware and signal processing algorithms has been developed. In this work, we present the different signal processing steps in HD-UPP and show experimental results from female minipigs.MethodsWe use a special microtip catheter with high angular pressure resolution and an integrated inclination sensor. Signals from the catheter are filtered and time-correlated artifacts removed. A signal reconstruction algorithm processes pressure data into a detailed pressure image on the urethra’s inside. Finally, the pressure distribution on the urethra’s outside is calculated through deconvolution. A mathematical model of the urethra is contained in a point-spread-function (PSF) which is identified depending on geometric and material properties of the urethra. We additionally investigate the PSF’s frequency response to determine the relevant frequency band for pressure information on the urinary sphincter.ResultsExperimental pressure data are spatially located and processed into high resolution pressure images. Artifacts are successfully removed from data without blurring other details. The pressure distribution on the urethra’s outside is reconstructed and compared to the one on the inside. Finally, the pressure images are mapped onto the urethral geometry calculated from inclination and position data to provide an integrated image of pressure distribution, anatomical shape, and location.ConclusionsWith its advanced sensing capabilities, the novel microtip catheter collects an unprecedented amount of urethral pressure data. Through sequential signal processing steps, physicians are provided with detailed information on the pressure distribution in and around the urethra. Therefore, HD-UPP overcomes many current limitations of conventional UPP and offers the opportunity to evaluate urethral structures, especially the sphincter, in context of the correct anatomical location. This could enable the development of focal therapy approaches in the treatment of SUI.

Precise injection of human mesenchymal stromal cells in the urethral sphincter complex of Göttingen minipigs without unspecific bulking effects

To investigate if injection of cells in the urethral sphincter complex causes unspecific bulking effects.

Eliminating pulse-induced artifacts in Urethral Pressure data.

Urethral Pressure Profilometry (UPP) is a tool in the diagnosis of urinary incontinence. The pressure profile along the urethra is measured by a special catheter in order to assess the contraction strength of the sphincter muscle. The use of microtip catheters with several pressure sensors and an integrated acceleration sensor enables signal reconstruction of the pressure distribution on the urethras inside. Experimental data from minipigs exhibit artifact patterns in the pressure data. It is shown that these artifacts are caused by vascular pulsation in the sphincter structure. We therefore investigate different methods exploiting the time-correlation of the artifacts to eliminate pulse-induced artifacts in the pressure data without compromising the actual signal. Evaluation of these methods applied to experimental data conclude this work showing that both an Input-Model and Principal Component Analysis Decorrelation are effective at removing the artifacts.

Assessing the reproducibility of high definition urethral pressure profilometry and its correlation with an air‐charged system

Recently, a new urodynamic method for the assessment of stress urinary incontinence called high definition urethral pressure profilometry (HD‐UPP) has been introduced. This method combines a novel microtip catheter with advanced signal processing to enable spatial data location and the reconstruction of a pressure image inside the urethra. In order to assess the reproducibility of HD‐UPP data, we statistically evaluate HD‐UPP datasets and compare them to data from a double balloon air‐charged system.

MP40-09 ESTABLISHMENT OF A NEW LARGE ANIMAL MODEL FOR STRESS URINARY INCONTINENCE USING GERMAN LANDRACE PIGS

voiding and UUI, respectively. There were 201 (11.5%) in the 0wet/ happy0 group (96 RP; 64 TO; 41 ARF). Postoperative SUI status was: 139 (69%) improved, 13 (6%) de novo, and 9 (4%) worse. Additional surgeries during the FU period were: 6% prolapse repair, 3% bulking, 2% repeat sling, 2% sling revision, and 1% sling incision. In 62 women having sling only, 89% had SUI improvement. Concomitant surgery inversely correlated with satisfaction. CONCLUSIONS: Even if initial cure is not achieved, SUI improvement typically leads to satisfaction after sling surgery. Along with UUI, postoperative pain, prolapse, and voiding problems contribute to dissatisfaction with sling surgery; however, these events are strongly associated with concomitant pelvic surgical procedures. Proper counseling regarding expectations after sling, with or without concomitant surgery, is paramount in improving outcomes and satisfaction.

MP36-01 COLLAGEN CELL CARRIER FOR URETHRAL RECONSTRUCTIVE SURGERY: FIRST RESULTS OF A LONG-TERM MINIPIG MODEL

INTRODUCTION AND OBJECTIVES: Regarding urethral reconstruction of urethral stricures we demonstrated in a previous shortterm pilot study that human urothelial cells (HUC) seeded on a bovine collagen cell carrier (CCC), used as a xenograft in minipigs is technically feasible for urethral reconstruction. The aim of this following study was to evaluate the use of CCC in a long-term animal model and to compare it with primary surgical reconstruction without CCC of the porcine urethra. METHODS: Twelve male G€ ottingen minipigs with immunosuppression (cyclosporine A) were used for this study. Eight weeks after urethral stricture induction and protective vesicostomy animals were subdivided in a short-term group (4 pigs with HUC seeded CCC) and a long-term group (2 pigs with static HUC seeded CCC, 2 pigs with CCConly, 2 pigs with bioreactor cultivated dynamic HUC seeded CCC). As a control-group SHAM operated animals were selected (2 pigs without CCC and primary urethral reconstruction). HUC obtained from human benign ureteral tissue were stained by PKH26 before seeding on CCC. Follow-up timeframe was 2 and 4 weeks in the short-term group, 2 weeks in the sham operated group and 3 months in the long-term group. Hereafter animals were euthanized. Urethrography, histological assessment and immunofluorescence were performed. RESULTS: Surgery was well tolerated and technically feasible in all 12 mini-pigs. In the final urethrography no remaining significant stricture could be detected in the long-term group. In contrast both SHAM operated pigs showed a persistent urographic urethral stricture in the final examination. A radiological extravasation was only found in short-term (3/4) and SHAM (1/2) animals but not in the long-term group. The final histological examination showed the CCC close to the previously suture-tagged operating area (range 0.5-1.2 mm). In case of HUC seeded CCC near porcine urothelium PKH26 positive areas were found even if partially detached from CCC. However, porcine urethra revealed intact urothelium in the long-term group expressing CK20, E-Cadherin and ZO-1 whereas 1 of 2 SHAM animals had a histologically discontinuous urethra. CONCLUSIONS: Compared to the control-group with primary urethral reconstruction CCC with or without HUC seems to increase the stability of the reconstructed urethra and supports survival and growth of seeded urothelial cells leading to an intact regeneration of the urothelial tissue. Finally, this study demonstrates that CCC in minipigs is technically feasible showing promising results for further studies.

C10 Generation and characterisation of a transgenic rat model of huntington's disease-like 4 (HDL4), also called spinocerebellar ataxia type 17 (SCA17)

Huntingtons disease-like 4 (HDL4), also called spinocerebellar ataxia type 17, is an autosomal-dominant, late-onset neurodegenerative disorder caused by CAG repeat expansions in the TATA-box-binding protein (TBP), an ubiquitously expressed transcription factor. The clinical features of HDL4 closely resembled those of Huntingtons disease, including uncontrolled movements, emotional problems, and loss of thinking ability. To further investigate this devastating disease and additionally find a good model for treatment studies, we generated the first transgenic rat model of HDL4, which carries a full human cDNA fragment of the TBP gene with 64 CAG repeats under the control of the murine prion protein promoter (PrP-TBP64Q). In total we obtained ten positive founder animals, whereof only five transmitted the transgene. On the basis of the expression level of mutant TBP as well as the distribution of mutant TBP in the different brain regions we chose one of these five lines (line 8.4) for further characterisation. This line shows a strong expression of the mutant TBP protein in the cerebellum and a moderate expression in the olfactory bulb, brainstem and cortex. HDL4 rats showed an ataxia-like phenotype and impaired motor coordination and balance capabilities in the beam walking test. Additionally, HDL4 rats had a significantly lower body weight than their wildtype littermates and showed decreased activity. At the age of 10 months neuropathological changes, such as misshaped Purkinje cells, degenerated dendrites as well as missing basket and stellate neurons were observed in the cerebellum of heterozygous transgenic HDL4 rats compared to wildtype littermates. By electron microscopy we demonstrated dark cell degeneration as well as moderate fibre degeneration in the striatum. Moreover, we observed decreased levels of dopamine receptor (D2R) by performing PET imaging. Altogether the present data shows that this animal model exhibits symptoms which mimic well the human HDL4 phenotype indicating that this rat model will be of great value for further studies of pathomechanisms in Huntingtons disease-like 4 and for therapeutic trials.

A33 Behavioural evaluation of Huntington's disease mouse models with an automated home cage system

Huntingtons disease (HD) is a neurodegenerative disease and is caused by an expanded trinucleotide repeat in the huntingtin gene. There are various animal models of HD which all mirror at least partially the behavioural and neuropathological phenotype of the human disease. Nevertheless, the results of the studies in HD animal models are inconsistent across laboratories because of the lack of standardised testing conditions and husbandry and the autotelic differences between the different lines. To avoid experimenter dependent effects in the behavioural evaluation of HD mice we have compared the YAC128 full length model (on a FVB/N background) and the Hdh Q111 knock-in mouse (on a C57Bl/6 background) with heterozygous HDHex4/5 knock-out mice using an automated home cage system at different ages. The Labmaster system measured automatically and in a standardised setting drinking, feeding and activity for a time period of 70 h. Therefore, it allows us to detect even subtle differences in circadian food and fluid consumption as well as locomotor activity with rearing behaviour. This is especially of importance in the ‘late onset’ full length models with a relatively mild and not rapidly progressive phenotype. Furthermore, it has been shown that expression levels of full length htt influence body weight in a dose dependent manner in YAC128, YAC18 and heterozygous Hdh knock-out mice. Our study gives us the opportunity to carefully characterise the relationship between different levels of htt and activity and food intake in vivo. First results will be presented.