Ectopic intracranial retinoblastoma in a 3.5-month-old infant without eye involvement and without evidence of heritability.

Heritable retinoblastoma can rarely be associated with a midline intracranial neuroblastic tumor, referred to as trilateral retinoblastoma. We present an unusual midline brain tumor in an infant that was identified as ectopic retinoblastoma by histopathology, DNA methylation analysis, and molecular genetic detection of biallelic somatic inactivation of the RB1 gene. There was no ocular involvement, and germline mutation was excluded. In this nonresectable tumor, treatment with systemic chemotherapy including high-dose therapy with autologous stem cell transplantation, but without definite local therapy, resulted in long-lasting tumor control.

Autosomal dominant spinal muscular atrophy with lower extremity predominance: A recognizable phenotype of BICD2 mutations.

INTRODUCTION: Heterozygous BICD2 gene mutations cause a form of autosomal dominant spinal muscular atrophy with lower extremity predominance (SMALED). METHODS: We analyzed the BICD2 gene in a selected group of 25 index patients with neurogenic muscle atrophy. RESULTS: We identified 2 new BICD2 missense mutations, c.2515G>A, p.Gly839Arg, in a family with autosomal dominant inheritance, and c.2202G>T, p.Lys734Asn, as a de novo mutation in an isolated patient with similar phenotype. The patients had congenital foot contractures, muscle atrophy of the legs, and slowly progressive weakness of the shoulder girdle. There was no apparent sensory or brain dysfunction. One patient died of unrelated reasons at age 52 years. Autopsy revealed no upper motor neuron and only moderate lower motor neuron loss, but there was distal corticospinal tract degeneration and marked neurogenic muscular atrophy. CONCLUSION: These findings give further insight into the clinical and pathoanatomical consequences of BICD2 mutations. Muscle Nerve 54: 496-500, 2016.

Differences in degradation behavior of two non-cross-linked collagen barrier membranes: an in vitro and in vivo study.

OBJECTIVES: Collagen barrier membranes are used in guided bone regeneration/guided tissue regeneration because of their excellent bio- and cytocompatibility. However, they are considered to have limitations in clinical outcome because of rapid and unpredictable degradation profiles. The aim of this study was to investigate the degradation behavior of two porcine-based, non-cross-linked collagen membranes in vitro and in vivo. MATERIALS AND METHODS: Remaix™ (RX; Matricel GmbH, Herzogenrath, Germany) and Bio-Gide® (BG; Geistlich Pharma AG, Wolhusen, Switzerland) membranes were characterized by testing mechanical strength, denaturation temperature, enzymatic degradation and hydroxyproline content in vitro (n = 5 up to 16). Thereafter, both membranes were implanted subcutaneously in rats (n = 20) for up to 20 weeks to investigate tissue compatibility with respect to membrane thickness. RESULTS: BG contained a significant higher hydroxyproline content compared with RX, but RX showed a higher stress at break (dry: 11.4 (SD 2.9) vs. 5.5 (SD 1.5) N/mm(2)), higher suture retention (wet: 5.6 (SD 1.3) vs. 2.7 (SD 0.7) N), increased denaturation temperature (55.1 (SD 1) vs. 49.4 (SD 0.6)°C) and an almost twofold reduction in degradation rate (15.6% (SEM 1.3)/h vs. 24.8% (SEM 2.9)/h) in vitro. In the rat model, both membranes showed excellent tissue compatibility without signs of inflammatory reactions. Shortly after implantation, RX and BG showed moderate infiltration of mononuclear cells that appeared not to be influenced by the surface texture of the membranes. In the histomorphometric analysis, both membranes showed significant different thickness over the 20 weeks period (P = 0.0002). Although the thickness remained almost stable during the first 9 weeks after implantation, after 20 weeks, the thickness of RX decreased only slightly, whereas BG showed a thickness loss of around 50% and stronger degradation than RX. Therefore, the higher stability of RX against biodegradation found in vitro was confirmed in the animal study. CONCLUSION: This study shows differences in the biodegradation characteristics of two non-cross-linked collagen membranes in vitro and in vivo. Whether the higher stability of RX is of clinical relevance should be analyzed in future clinical investigations.

Myelin protein zero mutation-related hereditary neuropathies: Neuropathological insight from a new nerve biopsy cohort.

Myelin protein zero (MPZ/P0) is a major structural protein of peripheral nerve myelin. Disease-associated variants in the MPZ gene cause a wide phenotypic spectrum of inherited peripheral neuropathies. Previous nerve biopsy studies showed evidence for subtype-specific morphological features. Here, we aimed at enhancing the understanding of these subtype-specific features and pathophysiological aspects of MPZ neuropathies. We examined archival material from two Central European centers and systematically determined genetic, clinical, and neuropathological features of 21 patients with MPZ mutations compared to 16 controls. Cases were grouped based on nerve conduction data into congenital hypomyelinating neuropathy (CHN; n = 2), demyelinating Charcot-Marie-Tooth (CMT type 1; n = 11), intermediate (CMTi; n = 3), and axonal CMT (type 2; n = 5). Six cases had combined muscle and nerve biopsies and one underwent autopsy. We detected four MPZ gene variants not previously described in patients with neuropathy. Light and electron microscopy of nerve biopsies confirmed fewer myelinated fibers, more onion bulbs and reduced regeneration in demyelinating CMT1 compared to CMT2/CMTi. In addition, we observed significantly more denervated Schwann cells, more collagen pockets, fewer unmyelinated axons per Schwann cell unit and a higher density of Schwann cell nuclei in CMT1 compared to CMT2/CMTi. CHN was characterized by basal lamina onion bulb formation, a further increase in Schwann cell density and hypomyelination. Most late onset axonal neuropathy patients showed microangiopathy. In the autopsy case, we observed prominent neuromatous hyperinnervation of the spinal meninges. In four of the six muscle biopsies, we found marked structural mitochondrial abnormalities. These results show that MPZ alterations not only affect myelinated nerve fibers, leading to either primarily demyelinating or axonal changes, but also affect non-myelinated nerve fibers. The autopsy case offers insight into spinal nerve root pathology in MPZ neuropathy. Finally, our data suggest a peculiar association of MPZ mutations with mitochondrial alterations in muscle.

Surgical Results and Microscopic Analysis of the Tissue Reaction following Implantation and Explantation of an Intraocular Implant for Epiretinal Stimulation in Minipigs.

AIMS: For the purpose of visual rehabilitation of subjects with photoreceptor degeneration, an implantable microelectronic device for epiretinal stimulation was developed. Our study aimed to show whether implantation and explantation could be conducted safely and to investigate tissue compatibility. METHODS: The device was implanted in 5 Göttinger minipigs. Four weeks later, the implant was surgical- ly removed. Histopathological examination that followed aimed at detecting inflammatory or proliferative changes. Stains used were hematoxylin and eosin, leukocyte common antigen, CD68 and glial fibrillary acidic protein. A grinding technique was used to visualize the retinal tissue in conjunction with the retinal tacks. RESULTS: The implantation of the devices was successful in all cases. The explantation was complicated by intraoperative hemorrhages. Complete explantation could only be achieved after modifying the implantation strategy. Histopathology revealed a mild degree of cystic disaggregation of the retina. Immunohistochemically, an increased glial fibrillary acidic protein expression of Müller cells was found, which shows a moderate glial cell activation. Inflammatory cells were absent. Using the grinding technique, tissue adjacent to the retinal tacks showed a mild gliosis. DISCUSSION: The viability of implantation and explantation of the implant in minipigs has been shown. The absence of immunoreactive cells or a considerable glial reaction suggest that the device may be considered safe and suitable for further implantation in humans.

Myocarditis in newborn wild-type BALB/c mice infected with the murine gamma herpesvirus MHV-68.

OBJECTIVES: Animal models of human Epstein-Barr virus (EBV) infection include EBV infection of primates and infection of mice with MHV-68, a further gamma herpesvirus (gamma-HV). We aimed at extending the MHV-68 model to study gamma-HV-related cardiac disease. METHODS: Newborn wild-type BALB/c- (n=107), wild-type C57BL/6- (n=17) and immunodeficient B6-(Rag1) mice (n=18) were infected by nasal inoculation and evaluated for histopathological changes as well as tissue viral loads. RESULTS: From day 5 on BALB/c mice showed myocardial viral replication. Whereas focal inflammation occurred simultaneously, necrosis was first observed 9 days post-infection. The maximum rates of necrosis (40%) and of focal inflammation (33%) were found after 10 to 12 and 33 to 35 days, respectively. Some animals developed persistent viral activity and inflammation throughout the observation period of three months. Inflammation was mainly related to T cell infiltrates. Although C57BL/6 mice also showed myocardial inflammation, necrosis was not found suggesting differences in the susceptibility to the virus in distinct mouse strains. In immunodeficient animals higher myocardial viral loads were observed compared to wild-type mice but no cardiac lesions, which suggests that the antiviral immune response contributed to the lesions. CONCLUSIONS: The model system presented here is the first to allow detailed studies on cardiac disease caused by gamma-HV infections and may facilitate the development of more specific treatment options for human cardiac EBV infection.

Correlation of Dynamic O-(2-[18F]Fluoroethyl)-L-Tyrosine Positron Emission Tomography, Conventional Magnetic Resonance Imaging, and Whole-Brain Histopathology in a Pretreated Glioblastoma: A Postmortem Study.

OBJECTIVE: Amino acid positron emission tomography (PET) using O-(2-[18F]fluoroethyl)-L-tyrosine (FET) provides important additional information on the extent of viable tumor tissue of glioblastoma compared with magnetic resonance imaging (MRI). Especially after radiochemotherapy, progression of contrast enhancement in MRI is equivocal and may represent either tumor progression or treatment-related changes. Here, the first case comparing postmortem whole-brain histology of a patient with pretreated glioblastoma with dynamic in vivo FET PET and MRI is presented. METHODS: A 61-year-old patient with glioblastoma initially underwent partial tumor resection and died 11 weeks after completion of chemoradiation with concurrent temozolomide. Three days before the patient died, a follow-up FET PET and MRI scan indicated tumor progression. Autopsy was performed 48 hours after death. After formalin fixation, a 7-cm bihemispherical segment of the brain containing the entire tumor mass was cut into 3500 consecutive 20µm coronal sections. Representative sections were stained with hematoxylin and eosin stain, cresyl violet, and glial fibrillary acidic protein immunohistochemistry. An experienced neuropathologist identified areas of dense and diffuse neoplastic infiltration, astrogliosis, and necrosis. In vivo FET PET, MRI datasets, and postmortem histology were co-registered and compared by 3 experienced physicians. RESULTS: Increased uptake of FET in the area of equivocal contrast enhancement on MRI correlated very well with dense infiltration by vital tumor cells and showed tracer kinetics typical for malignant gliomas. An area of predominantly reactive astrogliosis showed only moderate uptake of FET and tracer kinetics usually observed in benign lesions. CONCLUSIONS: This case report impressively documents the correct imaging of a progressive glioblastoma by FET PET.

Development of a Polymer-Based Biodegradable Neurovascular Stent Prototype: A Preliminary In Vitro and In Vivo Study.

Biodegradable stents are not established in neurovascular interventions. In this study, mechanical, radiological, and histological characteristics of a stent prototype developed for neurovascular use are presented. The elasticity and brittleness of PLA 96/4, PLDL 70/30, PCL, and PLGA 85/15 and 10/90 polymers in in vitro experiments are first analyzed. After excluding the inapt polymers, degradability and mechanical characteristics of 78 PLGA 85/15 and PLGA 10/90 stent prototypes are analyzed. After excluding PLGA 10/90 stents because of rapid loss of mass PLGA 85/15 stents in porcine in vivo experiments are analyzed. Angiographic occlusion rates 7 d, 1 month, 3 months, and 6 months after stent implantation are assessed. Histological outcome measures are the presence of signs of inflammation, endothelialization, and the homogeneity of degradation after six months. One case of stent occlusion occurs within the first 7 d. There is a prominent foreign-body reaction with considerable mononuclear and minor granulocytic inflammation combined with incomplete fragmental degradation of the struts. It is possible to produce a stent prototype with dimensions that fit the typical size of carotid arteries. Major improvements concerning thrombogenicity, degradation, and inflammatory response are required to produce biodegradable stents that are suitable for neurovascular interventions.

In vitro assessment of axonal growth using dorsal root ganglia explants in a novel three-dimensional collagen matrix.

The goal of this study was the development of a bioartificial nerve guide to induce axonal regeneration in the peripheral nervous system (PNS). In this in vitro study, the ability of a novel, 3-dimensional (3D), highly oriented, cross-linked porcine collagen scaffold to promote directed axonal growth has been studied. Collagen nerve guides with longitudinal guidance channels were manufactured using a series of chemical and mechanical treatments with a patented unidirectional freezing process, followed by freeze-drying (pore sizes 20-50 microm). Hemisected rat dorsal root ganglia (DRG) were positioned such that neural and non-neural elements could migrate into the collagen scaffold. After 21 days, S100-positive Schwann cells (SCs) migrated into the scaffold and aligned within the guidance channels in a columnar fashion, resembling "Bands of Büngner." Neurofilament-positive axons (mean length +/- SD 756 microm +/- 318 microm, maximum 1496 microm) from DRG neurons entered the scaffold where the growth within the guidance channels was closely associated with the oriented SCs. This study confirmed the importance of SCs in the regeneration process (neurotrophic theory). The alignment of SCs within the guidance channels supported directional axonal growth (contact guidance theory). The microstructural properties of the scaffold (open, porous, longitudinal pore channels) and the in vitro data after DRG loading (axonal regeneration along migrated and columnar-aligned SCs resembling "Band of Büngner") suggest that this novel oriented 3D collagen scaffold serves as a basis for future experimental regeneration studies in the PNS.

Dynamic O-(2-18F-fluoroethyl)-L-tyrosine positron emission tomography differentiates brain metastasis recurrence from radiation injury after radiotherapy.

Background: The aim of this study was to investigate the potential of dynamic O-(2-[18F]fluoroethyl)-L-tyrosine (18F-FET) PET for differentiating local recurrent brain metastasis from radiation injury after radiotherapy since contrast-enhanced MRI often remains inconclusive. Methods: Sixty-two patients (mean age, 55 ± 11 y) with single or multiple contrast-enhancing brain lesions (n = 76) on MRI after radiotherapy of brain metastases (predominantly stereotactic radiosurgery) were investigated with dynamic 18F-FET PET. Maximum and mean tumor-to-brain ratios (TBRmax, TBRmean) of 18F-FET uptake were determined (20-40 min postinjection) as well as tracer uptake kinetics (ie, time-to-peak and slope of time-activity curves). Diagnoses were confirmed histologically (34%; 26 lesions in 25 patients) or by clinical follow-up (66%; 50 lesions in 37 patients). Diagnostic accuracies of PET parameters for the correct identification of recurrent brain metastasis were evaluated by receiver-operating-characteristic analyses or the chi-square test. Results: TBRs were significantly higher in recurrent metastases (n = 36) than in radiation injuries (n = 40) (TBRmax 3.3 ± 1.0 vs 2.2 ± 0.4, P < .001; TBRmean 2.2 ± 0.4 vs 1.7 ± 0.3, P < .001). The highest accuracy (88%) for diagnosing local recurrent metastasis could be obtained with TBRs in combination with the slope of time-activity curves (P < .001). Conclusions: The results of this study confirm previous preliminary observations that the combined evaluation of the TBRs of 18F-FET uptake and the slope of time-activity curves can differentiate local brain metastasis recurrence from radiation-induced changes with high accuracy. 18F-FET PET may thus contribute significantly to the management of patients with brain metastases.

Experimental implantation and long-term testing of an intraocular vision aid in rabbits.

OBJECTIVE: To develop an intraocular vision aid to provide artificial vision in severely traumatized eyes, where neuroretinal function could be preserved but irreversible anterior segment opacification resulted in blindness. METHODS: The basis of an intraocular vision aid is in principle a telemetric circuit to bridge the opaque cornea and to allow for artificial light stimulation of the retina. The visual prosthesis comprises an external high-dynamic range complementary metal oxide semiconductor camera and digital signal processing unit and an intraocular miniaturized light-emitting diode array to project the image onto the retina. For in vivo testing of long-term function and biocompatibility, silicone-encapsulated active photodiodes were implanted in 13 pigmented rabbits and were followed up for up to 21 months. RESULTS: Lens extraction and stable fixation of the device in the ciliary sulcus were successful in all cases. For up to 21 months inductive energy transmission and wireless stimulation of the implants could be maintained. Electrophysiologic data and histology demonstrated a good tissue biocompatibility in the long-term follow-up. CONCLUSION: The results demonstrate the general feasibility and biocompatibility to implant and fixate an intraocular light-emitting diode prosthesis. Inductive energy transmission to the intraocular device and wireless light stimulation are assured in the long term but depend on meticulous water-impermeable encapsulation of the delicate microelectronic components. Clinical Relevance An intraocular vision aid compound system with a high-resolution light-emitting diode matrix might be a future treatment option to restore vision in blind eyes with severe anterior segment disorders.

Inflammatory pseudotumors of the central nervous system: report of 3 cases and a literature review.

Inflammatory pseudotumors (IPs), mostly benign lesions characterized by fibrotic ground tissue and polyclonal mononuclear infiltrate, may affect all organ systems. IPs originating in the central nervous system (IP-CNS) are very rare, and their distinct histopathologic features are poorly characterized. Three otherwise healthy patients (age 8, 15, and 17 years) presented with focal neurologic symptoms (seizures, n = 2; headaches, n = 1), corresponding to a left temporal, left occipital, and left frontal IP, respectively, extending from meningeal structures into brain tissue. After resection, no recurrence was observed in patient 1 during 5 years of follow-up, whereas patient 2 developed a rapidly progressive local recurrence and a second intracerebral lesion despite antiviral, immunosuppressive, antibiotic, and radiation therapy. In patient 3, who also showed local recurrences, sequential histopathologic investigations revealed transformation to a semimalignant fibrohistiocytic tumor. In this patient, anaplastic lymphoma kinase (ALK) expression was also positive, whereas it was negative in patient 1. A detailed literature analysis confirmed that most IP-CNS arise from dural/meningeal structures (n = 34). Intraparenchymatous (n = 7), mixed intraparenchymatous/meningeal (n = 4), and intraventricular lesions (n = 7) or IP extending per continuitatem from intracerebral to extracerebral sites (n = 5) were rare. The recurrence rate was 40% within 2 years in general. It was increased after incomplete resection and in female patients (multivariate Cox regression model, P < 0.02). Although rare, IP-CNS are important differential diagnoses among tumor-like intracranial lesions. Their potential risk of malignant transformation and high risk of recurrence necessitate close follow-up, especially when resection is incomplete. Prospective multicenter trials are needed to optimize classification and treatment of this rare inflammatory lesion.

Flow cytometric cerebrospinal fluid analysis in children.

Flow cytometry (FC) is of increasing importance for the analysis of cerebrospinal fluid (CSF) lymphocytes because of its ability to detect a large spectrum of cellular characteristics (granularity, volume, surface antigen expression) even in small amounts of cells. Data on CSF FC in children are very limited. Here, we summarize our 3-year experience of CSF FC routinely performed in pediatric patients with assumed inflammatory central nervous system (CNS) disease. Among 109 samples sent for analysis, flow cytometric detection of major leukocyte subsets was possible in 78% (85 out of 109), which exceeds the 31% rate of our retrospective microscopic pediatric control group. Apart from physiologic lymphocytes (100%) or monocytes (48%), 11 out of these 85 samples showed granulocytes, two showed proliferated monocytes, and nine displayed proliferated lymphocytes. In most children, the proliferated lymphocytes consisted of a polyclonal population of CD4+ and CD8+ T cells. Compared with literature data, eight children showed abnormally composed lymphocyte subsets (surface antigen expression) within the main lymphocyte population. However, none of these changes was specific for distinct diseases or allowed a distinction between patients with and without primary inflammatory processes. These data suggest that CSF FC may be the most effective modality to differentiate major CSF leukocyte subsets. At present, further differentiation of distinct cell populations, such as proliferated lymphocytes, is of limited clinical impact. This may, however, gain increasing interest in the future.

Survival in second primary malignancies of patients with head and neck cancer.

Second primary tumours occur frequently in patients with a history of head and neck malignancies. Delays in making an early and correct diagnosis can seriously affect the therapy management and survival. This was a retrospective study of 120 patients with a history of head and neck cancer, presenting with a second primary tumour. Current follow-up strategies and the use of routine sonographic imaging of the head and neck regions were evaluated, and the impact that tumour chronology, the tumour site and the various treatment modalities have on the survival were assessed. Forty-two per cent of patients developed a metachronous second malignancy more than five years after diagnosis of the index tumour. The accuracy of colour-duplex sonography in detection of second primaries in the head and neck was 82.3 per cent. First and second primary tumours located in the larynx were observed to have the highest five-year survival rate. Patients who developed metachronous tumours had a five-year survival rate of 68.9 per cent for the index tumours, and a 26 per cent five-year survival rate with the occurrence of a second neoplasm. With synchronous tumours a mean survival time of 18 months and a five-year survival rate of 11.9 per cent was found (p < 0.0001). Where clinically appropriate an aggressive treatment strategy was employed and yielded the most favourable results with a five-year survival rate of 66.8 per cent and 35.9 per cent for index tumours and second primary malignancies, respectively. Since more than 40 per cent of the metachronous second primaries in patients with a history of head and neck malignancy occur beyond the five-year follow-up period, an extended protocol with individually adjusted close monitoring of high-risk patients seems appropriate. Colour-duplex sonography is a valuable screening investigation for the early detection of second primary tumours. The treatment of a second primary is often less successful than for the same malignancy occurring primarily. The prognosis of synchronous tumours is significantly lower when compared to malignancies of a metachronous nature, despite some encouraging individual results. Only the early implementation of aggressive treatment methods for second primaries is successful in terms of survival.

Modulation of hippocampal neuroplasticity by Fas/CD95 regulatory protein 2 (Faim2) in the course of bacterial meningitis.

Fas-apoptotic inhibitory molecule 2 (Faim2) is a neuron-specific membrane protein and a member of the evolutionary conserved lifeguard apoptosis regulatory gene family. Its neuroprotective effect in acute neurological diseases has been demonstrated in an in vivo model of focal cerebral ischemia. Here we show that Faim2 is physiologically expressed in the human brain with a changing pattern in cases of infectious meningoencephalitis.In Faim2-deficient mice, there was increased caspase-associated hippocampal apoptotic cell death and an increased extracellular signal-regulated kinase pattern during acute bacterial meningitis induced by subarachnoid infection with Streptococcus pneumoniae type 3 strain. However, after rescuing the animals by antibiotic treatment, Faim2 deficiency led to increased hippocampal neurogenesis at 7 weeks after infection. This was associated with improved performance of Faim2-deficient mice compared to wild-type littermates in the Morris water maze, a paradigm for hippocampal spatial learning and memory. Thus, Faim2 deficiency aggravated degenerative processes in the acute phase but induced regenerative processes in the repair phase of a mouse model of pneumococcal meningitis. Hence, time-dependent modulation of neuroplasticity by Faim2 may offer a new therapeutic approach for reducing hippocampal neuronal cell death and improving cognitive deficits after bacterial meningitis.

The proximal medial sural nerve biopsy model: a standardised and reproducible baseline clinical model for the translational evaluation of bioengineered nerve guides.

Autologous nerve transplantation (ANT) is the clinical gold standard for the reconstruction of peripheral nerve defects. A large number of bioengineered nerve guides have been tested under laboratory conditions as an alternative to the ANT. The step from experimental studies to the implementation of the device in the clinical setting is often substantial and the outcome is unpredictable. This is mainly linked to the heterogeneity of clinical peripheral nerve injuries, which is very different from standardized animal studies. In search of a reproducible human model for the implantation of bioengineered nerve guides, we propose the reconstruction of sural nerve defects after routine nerve biopsy as a first or baseline study. Our concept uses the medial sural nerve of patients undergoing diagnostic nerve biopsy (≥ 2 cm). The biopsy-induced nerve gap was immediately reconstructed by implantation of the novel microstructured nerve guide, Neuromaix, as part of an ongoing first-in-human study. Here we present (i) a detailed list of inclusion and exclusion criteria, (ii) a detailed description of the surgical procedure, and (iii) a follow-up concept with multimodal sensory evaluation techniques. The proximal medial sural nerve biopsy model can serve as a preliminary nature of the injuries or baseline nerve lesion model. In a subsequent step, newly developed nerve guides could be tested in more unpredictable and challenging clinical peripheral nerve lesions (e.g., following trauma) which have reduced comparability due to the different nature of the injuries (e.g., site of injury and length of nerve gap).

Cetuximab induces eme1-mediated DNA repair: a novel mechanism for cetuximab resistance.

Overexpression of the epidermal growth factor receptor (EGFR) is observed in a large number of neoplasms. The monoclonal antibody cetuximab/Erbitux is frequently applied to treat EGFR-expressing tumors. However, the application of cetuximab alone or in combination with radio- and/or chemotherapy often yields only little benefit for patients. In the present study, we describe a mechanism that explains resistance of both tumor cell lines and cultured primary human glioma cells to cetuximab. Treatment of these cells with cetuximab promoted DNA synthesis in the absence of increased proliferation, suggesting that DNA repair pathways were activated. Indeed, we observed that cetuximab promoted the activation of the DNA damage response pathway and prevented the degradation of essential meiotic endonuclease 1 homolog 1 (Eme1), a heterodimeric endonuclease involved in DNA repair. The increased levels of Eme1 were necessary for enhanced DNA repair, and the knockdown of Eme1 was sufficient to prevent efficient DNA repair in response to ultraviolet-C light or megavoltage irradiation. These treatments reduced the survival of tumor cells, an effect that was reversed by cetuximab application. Again, this protection was dependent on Eme1. Taken together, these results suggest that cetuximab initiates pathways that result in the stabilization of Eme1, thereby resulting in enhanced DNA repair. Accordingly, cetuximab enhances DNA repair, reducing the effectiveness of DNA-damaging therapies. This aspect should be considered when using cetuximab as an antitumor agent and suggests that Eme1 is a negative predictive marker.

Fetuin-a in the developing brain.

The serum protein fetuin-A is essential for mineral homeostasis and shows immunomodulatory functions, for example by binding to TGF superfamily proteins. It proved neuroprotective in a rat stroke model and reduced lethality after systemic lipopolysaccharide challenge in mice. Serum fetuin-A concentrations are highest during intrauterine life. Different species show intrauterine cerebral fetuin-A immunoreactivity, suggesting a contribution to brain development. We therefore aimed at specifying fetuin-A immunoreactivity in brains of newborn rats (age P0-P28) and human neonates (20-40 weeks of gestation). In humans and rats, fetuin-A was found in cortex, white matter, subplate, hippocampus, subventricular zone, and ependymal cells which supports a global role for brain function. In rats, overall fetuin-A immunoreactivity decreased with age. At P0 fetuin-A immunoreactivity affected most brain structures. Thereafter, it became increasingly restricted to distinct cells of the hippocampus, cingular gyrus, periventricular stem cell layer, and ependyma. In ependymal cells the staining pattern complied with active transependymal transport from cerebrospinal fluid. Double immunofluorescence studies revealed colocalization with NeuN (mature neurons), beta III tubulin (immature neurons), GFAP (astrocytes), and CD68 (activated microglia). This points to a role of fetuin-A in different brain functional systems. In human neonatal autopsy cases, frequently affected from severe neurological and non-neurological diseases, fetuin-A immunoreactivity was heterogeneous and much less associated with age than in healthy tissues studied earlier, suggesting an impact of exogeneous noxious factors on fetuin-A regulation. Further research on the role of fetuin-A in the neonatal brain during physiological and pathological conditions is recommended.

Uptake of O-(2-[18F]fluoroethyl)-L-tyrosine in reactive astrocytosis in the vicinity of cerebral gliomas.

UNLABELLED: PET using O-(2-[(18)F]fluoroethyl)-L-tyrosine ((18)F-FET) allows improved imaging of tumor extent of cerebral gliomas in comparison to MRI. In experimental brain infarction and hematoma, an unspecific accumulation of (18)F-FET has been detected in the area of reactive astrogliosis which is a common cellular reaction in the vicinity of cerebral gliomas. The aim of this study was to investigate possible (18)F-FET uptake in the area of reactive gliosis in the vicinity of untreated and irradiated rat gliomas. METHODS: F98-glioma cells were implanted into the caudate nucleus of 33 Fisher CDF rats. Sixteen animals remained untreated and in 17 animals the tumor was irradiated by Gamma Knife 5-8 days after implantation (2/50 Gy, 3/75 Gy, 6/100 Gy, 6/150 Gy). After 8-17 days of tumor growth the animals were sacrificed following injection of (18)F-FET. Brains were removed, cut in coronal sections and autoradiograms of (18)F-FET distribution were produced and compared with histology (toluidine blue) and reactive astrogliosis (GFAP staining). (18)F-FET uptake in the tumors and in areas of reactive astrocytosis was evaluated by lesion to brain ratios (L/B). RESULTS: Large F98-gliomas were present in all animals showing increased (18)F-FET-uptake which was similar in irradiated and non-irradiated tumors (L/B: 3.9 ± 0.8 vs. 4.0 ± 1.3). A pronounced reactive astrogliosis was noted in the vicinity of all tumors that showed significantly lower (18)F-FET-uptake than the tumors (L/B: 1.5 ± 0.4 vs. 3.9 ± 1.1). The area of (18)F-FET-uptake in the tumor was congruent with histological tumor extent in 31/33 animals. In 2 rats irradiated with 150 Gy, however, high (18)F-FET uptake was noted in the area of astrogliosis which led to an overestimation of the tumor size. CONCLUSIONS: Reactive astrogliosis in the vicinity of gliomas generally leads to only a slight (18)F-FET-enrichment that appears not to affect the correct definition of tumor extent for treatment planning.

The role of microstructured and interconnected pore channels in a collagen-based nerve guide on axonal regeneration in peripheral nerves.

The use of bioengineered nerve guides as alternatives for autologous nerve transplantation (ANT) is a promising strategy for the repair of peripheral nerve defects. In the present investigation, we present a collagen-based micro-structured nerve guide (Perimaix) for the repair of 2 cm rat sciatic nerve defects. Perimaix is an open-porous biodegradable nerve guide containing continuous, longitudinally orientated channels for orientated nerve growth. The effects of these nerve guides on axon regeneration by six weeks after implantation have been compared with those of ANT. Investigation of the regenerated sciatic nerve indicated that Perimaix strongly supported directed axon regeneration. When seeded with cultivated rat Schwann cells (SC), the Perimaix nerve guide was found to be almost as supportive of axon regeneration as ANT. The use of SC from transgenic green-fluorescent-protein (GFP) rats allowed us to detect the viability of donor SC at 1 week and 6 weeks after transplantation. The GFP-positive SC were aligned in a columnar fashion within the longitudinally orientated micro-channels. This cellular arrangement was not only observed prior to implantation, but also at one week and 6 weeks after implantation. It may be concluded that Perimaix nerve guides hold great promise for the repair of peripheral nerve defects.