Recently, we discovered a novel serum and cerebrospinal fluid (CSF) autoantibody (anti-Ca) to Purkinje cells in a patient with autoimmune cerebellar ataxia (ACA) and identified the RhoGTPase-activating protein 26 (ARHGAP26; alternative designations include GTPase regulator associated with focal adhesion kinase pp125, GRAF, and oligophrenin-1-like protein, OPHN1L) as the target antigen. Here, we report on two new cases of ARHGAP26 autoantibody-positive ACA that were first diagnosed after publication of the index case study. While the index patient developed ACA following an episode of respiratory infection with still no evidence for malignancy 52 months after onset, neurological symptoms heralded ovarian cancer in one of the patients described here. Our finding of anti-Ca/anti-ARHGAP26 antibodies in two additional patients supports a role of autoimmunity against ARHGAP26 in the pathogenesis of ACA. Moreover, the finding of ovarian cancer in one of our patients suggests that anti-Ca/anti-ARHGAP26-positive ACA might be of paraneoplastic aetiology in some cases. In conclusion, testing for anti-Ca/anti-ARHGAP26 should be included in the diagnostic work-up of patients with ACA, and an underlying tumour should be considered in patients presenting with anti-Ca/ARHGAP26 antibody-positive ACA.
The discovery of a novel serum autoantibody (termed NMO-IgG or AQP4-Ab) in a subset of patients in 2004 has revived interest in neuromyelitis optica (NMO). While the history of classical multiple sclerosis has been extensively studied, only little is known about the history of NMO. In the present article, we provide a comprehensive review of the early history of this rare but intriguing syndrome. We trace the origins of the concept of NMO in the 19th century medical literature and follow its evolution throughout the 20th and into the 21st century. Finally, we discuss recent proposals to revise the concept of NMO and explain why there is indeed a need for a more systematic and descriptive nomenclature.
Human African Trypanosomiasis (HAT) is a neglected tropical disease that mainly affects the poorest people in sub Saharan Africa. HAT is caused by two subspecies of Trypanosoma brucei; T. b. rhodesiense is found in Eastern Africa and causes the acute form of the disease, while T. b. gambiense is found in Western Africa and causes the chronic form of the disease. With no reliable diagnostic screening test, available drugs being rather toxic, and emerging cases of drug resistant strains, research on the molecular aspects of the trypanosome is being carried out with the hope of identifying potential drug targets and diagnostic markers. Since most studies are carried out on cultured blood stream trypanosomes, the extent to which these parasites are representative of a real human infection is not known. Therefore the aim of this study was to analyze the transcriptome of clinical isolates of T. b. rhodesiense from patient peripheral blood and cerebral spinal fluid by high throughput sequencing. But given the low parasitaemia during active infection, I developed a splice leader priming based Polymerase chain reaction method to specifically amplify nanogram amounts of trypanosome total RNA in microgram amounts of Human cellular RNA, to an amount sufficient for sequencing. The amplification method resulted in trypanosome transcripts covering 60% of the T. brucei 6772 unique genes, and with an expression threshold of 5 Rpkm. The sequenced amplified libraries (four replicates) were highly reproducible and comparable to unamplified libraries generated in the same way. However a comparison to the conventional RNASeq generated library showed distortions in the transcriptome, which could be corrected for and used to analyze clinical samples. An analysis of methods used to purify trypanosomes from blood showed that; even though DEAE chromatography and reticulocyte lysis resulted in 10 times more parasites than those in the buffy coat isolation method, reticulocyte lysis resulted in distortion of the transcriptome. However the DEAE chromatography trypanosomes transcriptome which was more comparable to the buffy coat, was not highly reproducible. The analysis of genomes from the trypanosomes isolated from the patients showed a level of heterogeneity between the samples with significant gene copy number variations observed mainly in the multi copy genes.
Einen zellulären "Schalter" für das Langzeitgedächtnis haben Forscher der Universität Heidelberg identifiziert. Am Interdisziplinären Zentrum für Neurowissenschaften (IZN) untersuchten sie Gehirne von Taufliegen beim Lernen. Dabei zeigte sich, dass es in den Zellkernen bestimmter Neuronen zu einer Anreicherung des Botenstoffes Kalzium kommt. Dieses Signal sehen die Forscher als Auslöser der Produktion sogenannter "Gedächtnisproteine". Wird dieser Kalzium-Schalter im Zellkern blockiert, bilden die Fliegen kein Langzeitgedächtnis mehr aus. Eine Erkenntnis, die auch für das Erinnern beim Menschen entscheidend sein könnte.
In the dorsal diencephalon of all vertebrates, the habenular neurocircuit transfers cognitive information from the forebrain into the ventral mid- and hindbrain via long axon fibers in the stria medullaris (SM) and fasciculus retroflexus (FR) on both sides of the brain. How these axons navigate through the brain and whether communication between brain hemispheres is required during the formation of this neuronal network is still an open question. The bilaterally formed habenulae in the dorsal diencephalon in zebrafish consist of the asymmetrically formed dorsal habenula nucleus (dHb) and the symmetric ventral habenula nucleus (vHb). While development of the dHb has been well described, the origin of the vHb and the genetic cascades underlying its development are not known. We use the habenular network as a model to investigate how axon elongation is coordinated during embryonic development. This can best be done by recording its development in-vivo. As this neural circuit takes at least 4 days to develop and spans about 300 µm in anterior-posterior and dorso-ventral direction, we needed to develop a novel assay to investigate its development in the living zebrafish embryo. In our studies, we identified a transgenic line of zebrafish expressing GFP throughout the habenular neurocircuit development in all subnuclei and their efferent projections. Combining optimised in-vivo 2-photon (2-PM) long-term image recording and colour code analysis with focal laser ablation of neurons, we discovered a neuronal network essential for dorsal habenular axon elongation and pathfinding. We present evidence that a bilateral cluster of early projecting neurons in the thalamus (ThEPC) functions as intermediate target for dHb axonal elongation via ipsilateral short- and contralateral long-range axonal communication between the two brain hemispheres. Moreover, we show that a subset of ThEPC neurons contributes to the forming ventral habenula, which development is controlled by tcf7l2 mediated Wnt/beta-catenin signalling.
In the following study the mouse mutant cobblestone (cbs) concerning the development of the forebrain was analyzed. The cbs mutation was uncovered by an ethyl-nitroso-urea (ENU) genetic screen, using a mouseline called tauGFP. At the beginning of the analysis of the cbs mutation, the phenotype of the cbs/cbs mouse mutant was already known, but because of the mutagenic ability of ENU, which causes random mutations, the affected gene was unclear. By applying the method of positional cloning the gene intraflagellar transport 88 (Ift88) was identified as the candidate gene. A detailed analysis of mRNA levels of Ift88 in the cbs/cbs mutant was undertaken by Northen Blot analysis as well as quantitative real-time RT-PCR. At the same time the Ift88 protein levels were also investigated by Western blot analysis. A complementation analysis by crossing cbs heterozygotes to mice heterozygous for a targeted deletion of the Ift88 gene (Ift88tm1.1Bky) (Haycraft et al., 2007) was done to ascertain, if the genetic defect in the cbs/cbs mutant is located in the Ift88 gene. In the represented study it could be shown that cbs is a hypomorphic allele of the gene Ift88, in which both Ift88 mRNA and protein levels are reduced by 70% to 80%, respectively. A detailed analysis by in situ hybridization (ISH) was followed, using different markers, which are specific for various areas of the developing telencephalon such as Ttr1 for the choroid plexus, Wnt2b for the cortical hem, as well as EphB1 and Lhx2 for the hippocampal anlage. Furthermore both the dorsal-ventral and rostral-caudal compartmental boundaries of the forebrain were investigated by ISH. cbs/cbs mutants display defects in the formation of dorsomedial telencephalic structures, such as the choroid plexus, cortical hem and hippocampus. Furthermore mutants exhibit a relaxation of both dorsal-ventral and rostral-caudal compartmental boundaries of the forebrain, resulting in the intermixture of otherwise separated cell populations. It is further demonstrated that the proteolytic processing of Gli3 is reduced in the cbs/cbs mutant, leading to an accumulation of the full-length activator isoform. In addition the cbs/cbs mutant exhibits an upregulation of canonical Wnt signalling in the neocortex and in the caudal forebrain. Primary cilia, microtubule-based organelles that protrude from the surface of most cells of the vertebrate body, are dependent on Ift88 for their formation and maintenance. The ultrastructure and morphology of cilia of the ventricle of the cbs/cbs mutants was therefore simultaneously investigated by transmission and scanning electron microscopy. Surprisingly, examined cilia are still existing and intact in the cbs/cbs mutant. Taken together, these results indicate a fundamental role for primary cilia in the development of the forebrain.