Andreas Spuler

Contractures and hypertrophic cardiomyopathy in a novel FHL1 mutation

We investigated a large German family (n = 37) with male members who had contractures, rigid spine syndrome, and hypertrophic cardiomyopathy. Muscle weakness or atrophy was not prominent in affected individuals. Muscle biopsy disclosed a myopathic pattern with cytoplasmic bodies. We used microsatellite markers and found linkage to a locus at Xq26‐28, a region harboring the FHL1 gene. We sequenced FHL1 and identified a new missense mutation within the third LIM domain that replaces a highly conserved cysteine by an arginine (c.625T>C; p.C209R). Our finding expands the phenotypic spectrum of the recently identified FHL1‐associated myopathies and widens the differential diagnosis of Emery–Dreifuss–like syndromes. ANN NEUROL 2010;67:136–140

Statistical wall shear stress maps of ruptured and unruptured middle cerebral artery aneurysms

Haemodynamics and morphology play an important role in the genesis, growth and rupture of cerebral aneurysms. The goal of this study was to generate and analyse statistical wall shear stress (WSS) distributions and shapes in middle cerebral artery (MCA) saccular aneurysms. Unsteady flow was simulated in seven ruptured and 15 unruptured MCA aneurysms. In order to compare these results, all geometries must be brought in a uniform coordinate system. For this, aneurysms with corresponding WSS data were transformed into a uniform spherical shape; then, all geometries were uniformly aligned in three-dimensional space. Subsequently, we compared statistical WSS maps and surfaces of ruptured and unruptured aneurysms. No significant (p > 0.05) differences exist between ruptured and unruptured aneurysms regarding radius and mean WSS. In unruptured aneurysms, statistical WSS map relates regions with high (greater than 3 Pa) WSS to the neck region. In ruptured aneurysms, additional areas with high WSS contiguous to regions of low (less than 1 Pa) WSS are found in the dome region. In ruptured aneurysms, we found significantly lower WSS. The averaged aneurysm surface of unruptured aneurysms is round shaped, whereas the averaged surface of ruptured cases is multi-lobular. Our results confirm the hypothesis of low WSS and irregular shape as the essential rupture risk parameters.

Human satellite cells have regenerative capacity and are genetically manipulable

Muscle satellite cells promote regeneration and could potentially improve gene delivery for treating muscular dystrophies. Human satellite cells are scarce; therefore, clinical investigation has been limited. We obtained muscle fiber fragments from skeletal muscle biopsy specimens from adult donors aged 20 to 80 years. Fiber fragments were manually dissected, cultured, and evaluated for expression of myogenesis regulator PAX7. PAX7+ satellite cells were activated and proliferated efficiently in culture. Independent of donor age, as few as 2 to 4 PAX7+ satellite cells gave rise to several thousand myoblasts. Transplantation of human muscle fiber fragments into irradiated muscle of immunodeficient mice resulted in robust engraftment, muscle regeneration, and proper homing of human PAX7+ satellite cells to the stem cell niche. Further, we determined that subjecting the human muscle fiber fragments to hypothermic treatment successfully enriches the cultures for PAX7+ cells and improves the efficacy of the transplantation and muscle regeneration. Finally, we successfully altered gene expression in cultured human PAX7+ satellite cells with Sleeping Beauty transposon-mediated nonviral gene transfer, highlighting the potential of this system for use in gene therapy. Together, these results demonstrate the ability to culture and manipulate a rare population of human tissue-specific stem cells and suggest that these PAX7+ satellite cells have potential to restore gene function in muscular dystrophies.

In vitro study of near-wall flow in a cerebral aneurysm model with and without coils.

BACKGROUND AND PURPOSE: Coil embolization procedures change the flow conditions in the cerebral aneurysm and, therefore, in the near-wall region. Knowledge of these flow changes may be helpful to optimize therapy. The goal of this study was to investigate the effect of the coil-packing attenuation on the near-wall flow and its variability due to differences in the coil structure. MATERIALS AND METHODS: An enlarged transparent model of an ACA aneurysm was fabricated on the basis of CT angiography. The near-wall flow was visualized by using a recently proposed technique called Wall-PIV. Coil-packing attenuation of 10%, 15%, and 20% were investigated and compared with an aneurysmal flow without coils. Then the flow variability due to the coil introduction was analyzed in 10 experiments by using a packing attenuation of 15%. RESULTS: A small packing attenuation of 10% already alters the near-wall flow significantly in a large part of the aneurysmal sac. These flow changes are characterized by a slow flow with short (interrupted) path lines. An increased packing attenuation expands the wall area exposed to the altered flow conditions. This area, however, depends on the coil position and/or on the 3D coil structure in the aneurysm. CONCLUSIONS: To our knowledge, this is the first time the near-wall flow changes caused by coils in an aneurysm model have been visualized. It can be concluded that future hydrodynamic studies of coil therapy should include an investigation of the coil structure in addition to the coil-packing attenuation.

Experimental and Numerical Dye Washout Flow Visualization: Flow analysis in the realistic model of pathologic artery enlargement (aneurysm)

Flow visualization in realistic models is very important for the study of pathological vessel enlargements (aneurysms). Furthermore, flow visualization may help in treatment decisions. However, the most interesting parameter, the wall shear stress, is difficult to measure in vivo. This parameter can be provided by computational fluid dynamics. However, the numerical methods don’t visualize the results as does of the dye washout method — a method often used in flow studies. This experimental method simulates the cine angiograms acquired during contrast agent injection used in medicine. In this paper we present the dye washout visualization of CFD results and compare these results with the conventional dye washout experiments in the same aneurysm model under steady flow conditions.

Altered expression of cyclin A 1 in muscle of patients with facioscapulohumeral muscle dystrophy (FSHD-1).

Objectives Cyclin A1 regulates cell cycle activity and proliferation in somatic and germ-line cells. Its expression increases in G1/S phase and reaches a maximum in G2 and M phases. Altered cyclin A1 expression might contribute to clinical symptoms in facioscapulohumeral muscular dystrophy (FSHD). Methods Muscle biopsies were taken from the Vastus lateralis muscle for cDNA microarray, RT-PCR, immunohistochemistry and Western blot analyses to assess RNA and protein expression of cyclin A1 in human muscle cell lines and muscle tissue. Muscle fibers diameter was calculated on cryosections to test for hypertrophy. Results cDNA microarray data showed specifically elevated cyclin A1 levels in FSHD vs. other muscular disorders such as caveolinopathy, dysferlinopathy, four and a half LIM domains protein 1 deficiency and healthy controls. Data could be confirmed with RT-PCR and Western blot analysis showing up-regulated cyclin A1 levels also at protein level. We found also clear signs of hypertrophy within the Vastus lateralis muscle in FSHD-1 patients. Conclusions In most somatic human cell lines, cyclin A1 levels are low. Overexpression of cyclin A1 in FSHD indicates cell cycle dysregulation in FSHD and might contribute to clinical symptoms of this disease.

Reproducibility of Image-Based Analysis of Cerebral Aneurysm Geometry and Hemodynamics: An In-Vitro Study of Magnetic Resonance Imaging, Computed Tomography, and Three-Dimensional Rotational Angiography

BACKGROUND AND STUDY AIMS Image-based computational fluid dynamics (CFD) provides a means for analysis of biofluid mechanical parameters of cerebral aneurysms. This may enable patient-specific rupture risk analysis and facilitate treatment decisions. Application of different imaging methods may, however, alter the geometrical basis of these studies. The present study compares geometry and hemodynamics of an aneurysm phantom model acquired by means of magnetic resonance imaging (MRI), computed tomography (CT), and rotational angiography (3DRA). MATERIALS AND METHODS The phantom model of a basilaris artery aneurysm was fabricated based on data generated by CT angiography. This model underwent imaging by means of CT, MRI, and 3DRA. We compared the geometrical reconstructions using the original dataset with those obtained from CT, MRI, and 3DRA. Similarly, CFD analyses were performed using the four reconstructions (3DRA, MRI, CT, and original dataset). RESULTS MRI and the 3DRA-based reconstructions yield mean reconstruction errors of 0.097 mm and 0.1 mm, which are by a factor of 2.5 better than the CT reconstruction. The maximal error for the aneurysm radius (7.11 mm) measurement was found in the 3DRA reconstruction and was 3.8% (0.28 mm). A comparison of calculated time-averaged wall shear stress (WSS) shows good correlations for the entire surface and, separately, for the surface of the aneurysmal sack. The maximal error of 8% of the mean WSS calculation of the whole surface was found for the CT reconstruction. The calculations of the aneurysmal sack mean WSS from the MRI reconstruction were estimated to have a maximal error of 7%. CONCLUSION All three imaging techniques (CT, MRI, 3DRA) adequately reproduce aneurysm geometry and allow meaningful CFD analyses.

Hemodynamic impact of cerebral aneurysm endovascular treatment devices: coils and flow diverters

Coils and flow diverters or stents are devices successfully used to treat cerebral aneurysms. Treatment aims to reduce intra-aneurysmal flow, thereby separating the aneurysmal sac from the blood circulation. The focus and this manuscript combining literature review and our original research is an analysis of changes in aneurysmal hemodynamics caused by endovascular treatment devices. Knowledge of post-treatment hemodynamics is a path to successful long-term treatment. Summarizing findings on hemodynamic impact of treatment devices, we conclude: coiling and stenting do not affect post-treatment intra-aneurysmal pressure, but significantly alter aneurysmal hemodynamics through flow reduction and a change in flow structure. The impact of treatment devices on aneurysmal flow depends, however, on a set of parameters including device geometry, course of placement, parent vessel and aneurysm geometry.

Impact of imaging modality for analysis of a cerebral aneurysm: comparison between CT, MRI and 3DRA

Cerebral aneurysms are potentially life threatening. Computational fluid dynamics with non-invasive imaging methods can determine biofluidmechanical parameters of aneurysms. This study investigate the impact of the imaging techniques — magnetic resonance imaging (MRI), computed tomography (CT) and rotational angiography (3DRA) - to geometry reconstruction and calculated wall shear stress (WSS) distributions in a model of a basilaris artery. The comparison of the reconstructed geometries shows that the MRI and the 3DRA based reconstructions with mean 0.097 mm and 0.1 mm Hausdorff surface distance to the original geometry are better than the CT based reconstruction with mean 0.242 mm by similar resolutions of about 0.13 mm3 voxel sizes. Comparison of calculated mean WSS shows partially good correlation for the whole aneurysm bifurcation surface (4.02 Pa in the original geometry, 3.06 Pa in the CT, 3.62 Pa in the MRI and 4.17 Pa in the 3DRA based models).

In Vitro Study of Cerebrospinal Fluid Dynamics in a Shaken Basal Cistern after Experimental Subarachnoid Hemorrhage

Background Cerebral arterial vasospasm leads to delayed cerebral ischemia and constitutes the major delayed complication following aneurysmal subarachnoid hemorrhage. Cerebral vasospasm can be reduced by increased blood clearance from the subarachnoid space. Clinical pilot studies allow the hypothesis that the clearance of subarachnoid blood is facilitated by means of head shaking. A major obstacle for meaningful clinical studies is the lack of data on appropriate parameters of head shaking. Our in vitro study aims to provide these essential parameters. Methodology/Principal Findings A model of the basal cerebral cistern was derived from human magnetic resonance imaging data. Subarachnoid hemorrhage was simulated by addition of dyed experimental blood to transparent experimental cerebrospinal fluid (CSF) filling the model of the basal cerebral cistern. Effects of various head positions and head motion settings (shaking angle amplitudes and shaking frequencies) on blood clearance were investigated using the quantitative dye washout method. Blood washout can be divided into two phases: Blood/CSF mixing and clearance. The major effect of shaking consists in better mixing of blood and CSF thereby increasing clearance rate. Without shaking, blood/CSF mixing and blood clearance in the basal cerebral cistern are hampered by differences in density and viscosity of blood and CSF. Blood clearance increases with decreased shaking frequency and with increased shaking angle amplitude. Head shaking facilitates clearance by varying the direction of gravitational force. Conclusions/Significance From this in vitro study can be inferred that patient or head shaking with large shaking angles at low frequency is a promising therapeutic strategy to increase blood clearance from the subarachnoid space.