Phenotypic and functional differences between senescent and aged murine microglia

Microglia, the key innate immune cells in the brain, have been reported to drive brain aging and neurodegenerative disorders; however, few studies have analyzed microglial senescence and the impact of aging on the properties of microglia. In the present study, we characterized senescence- and aging-associated phenotypes of murine brain microglia using well-accepted markers, including telomere length, telomerase activity, expression of p16^INK4a, p21, p53, senescence-associated β-galactosidase, and a senescence-associated secretory phenotype. Quantitative real-time polymerase chain reaction analysis and a Telomeric Repeat Amplification Protocol assay indicated shortened telomeres and increased telomerase activity in senescent microglia, whereas telomeres remained unaltered and telomerase activity was reduced in aged microglia. Senescent microglia upregulated p16^INK4a, p21, and p53, whereas acutely isolated microglia from the aged brain only exhibited a modest upregulation of p16^INK4a. Senescent microglia showed decreased proliferation, while it was unchanged in aged microglia. Furthermore, microglia at late passages strongly upregulated expression of the senescent marker senescence-associated β-galactosidase. Senescent and aged microglia exhibited differential activation profiles and altered responses to stimulation. We conclude that microglia from the aged mouse brain do not show typical senescent changes because their phenotype and functional response strongly differ from those of senescent microglia in vitro.

Acute Stroke Treatment by Surgical Recanalization of Extracranial Internal Carotid Artery Occlusion: A Single Center Experience

Ischemic stroke due to an acute occlusion of the extracranial internal carotid artery (eICA) is associated with high morbidity and mortality. The best treatment option remains unclear. This study aims to increase the available therapeutic experience documented for surgical recanalization of acute eICA occlusions. We retrospectively reviewed all hospital records of the University Hospital Jena between 2006 and 2018 to identified patients with acute ischemic stroke due to an occlusion of the eICA who underwent emergent surgical recanalization. We analyzed clinical data, surgical reports, imaging data, and outpatient records. The primary outcome parameter was the modified Rankin Scale (mRS) at 3 months. During the survey, 12 patients (mean age: 62.3 ± 10.8 years; range: 35-87) underwent emergent surgical recanalization for an acutely symptomatic eICA occlusion. All patients presented with neurological deficits with a mean National Institutes of Health Stroke Scale score at admission of 15.0 ± 5.1 (range 2-23). Patients were selected for surgery mainly due to the extent of the perfusion mismatch, while stroke severity and age were also considered. The median time from symptom onset to surgery was 309 ± 122 minutes (range 112-650 minutes). Complete recanalization was obtained in all 12 patients. No patient deteriorated postoperatively, no intracranial hemorrhage was observed, and no patient died in the following 3 months. Favorable outcomes (mRS: 0-2) after 3 months were achieved in 7 of 12 patients. The current study adds support to previous findings that the surgical recanalization of acute eICA occlusions is a possible and safe treatment option. However, a critical patient selection based on mismatch size in perfusion imaging is crucially important for successful treatment.

The impact of motor impairment on the processing of sensory information

Sensorimotor adaptation is driven by mismatch errors between desired movements and actual movement outcomes. A mismatch error can be minimized by adjusting movements or by altering the interpretation of sensory information. While the effect of mismatch errors on the motor system has received much attention, the contribution of somatosensory feedback, particularly the sensory-motor interplay in the process of adaptation, remains poorly understood. Our study analyzes the impact of peripheral deefferentation on the plasticity of the brain networks responsible for sensory-motor adaptation, focusing particularly on changes in the processing of somatosensory information. For this aim, task-based and resting-state functional MRI was performed on 24 patients in the acute state of a left-sided idiopathic peripheral facial nerve palsy. The functional connectivity of cortical and subcortical networks was analyzed and compared to a healthy control group. We found a strong involvement of the somatosensory system and the thalamus in the adaptation process following an acute peripheral deefferentation. The investigated network shows the principal pattern of a reduced connectivity between cortical areas, while the connectivity to subcortical areas (the basal ganglia and the thalamus) is increased. We suggest that the increased connectivity between the subcortical and cortical structures indicates an active sensory-motor adaptation process. We further hypothesize that the decreased functional connectivity at the cortical level reflects an unsuccessful sensorimotor adaptation process due to the inability to solve the somatosensory-motor mismatch. These results extend our understanding of the somatosensory-motor interaction in response to a mismatch signal and highlight the importance of the thalamus in this process.

Weather, Weather Changes and the Risk of Bell's Palsy: A Multicenter Case-Crossover Study

BACKGROUND

To evaluate if weather or changes in weather are risk factors for Bell's palsy (BP) as exposure to draught of cold air has been popularly associated with the occurrence of BP.

METHODS

Using a multicenter hospital-based case-crossover study, we analyzed the association between ambient temperature, atmospheric pressure, relative air humidity or their 24 h changes and the risk for BP in 825 patients or subgroups.

RESULTS

One day following a 24 h increase in atmospheric pressure of more than 6 hPa, the risk for BP increased by 35% (OR 1.35; 95% CI 1.03-1.78) in the overall population. The risk for BP more than doubled in patients with diabetes mellitus after rapid variations in ambient temperature, independent of the direction (temperature decrease > 2.25°C; OR 2.15; 95% CI 1.08-4.25; temperature increase between 0.75 and 2.25°C; OR 2.88; 95% CI 1.63-5.10).

CONCLUSIONS

Our findings support the hypothesis of an association between certain weather conditions and the risk for BP with acute changes in atmospheric pressure and ambient temperature as the main risk factors. Additionally, contrasting results for risk of BP after temperature changes in the diabetic and non-diabetic subgroups support the paradigm of a diabetic facial palsy as a distinct disease entity.

Dual Task Effects on Visual Attention Capacity in Normal Aging

Older adults show higher dual task performance decrements than younger adults. While this is assumed to be related to attentional capacity reductions, the precise affected functions are not specified. Such specification is, however, possible based on the "theory of visual attention" (TVA) which allows for modeling of distinct attentional capacity parameters. Furthermore, it is unclear whether older adults show qualitatively different attentional effects or whether they show the same effects as younger adults experience under more challenging conditions. By varying the complexity of the secondary task, it is possible to address this question. In our study, participants performed a verbal whole report of briefly presented letter arrays. TVA-based fitting of report performance delivered parameters of visual threshold t0, processing speed C, and visual short-term memory (VSTM) storage capacity K. Furthermore, participants performed a concurrent motor task consisting of continuous tapping of a (simple or complex) sequence. Both TVA and tapping tasks were performed under single and dual task conditions. Two groups of 30 younger adults each performed either the simple or complex tapping, and a group of 30 older adults performed the simple tapping condition. In older participants, VSTM storage capacity declined under dual task conditions. While no such effect was found in younger subjects performing the simple tapping sequence under dual task conditions, the younger group performing the complex tapping task under dual task conditions also showed a significant VSTM capacity reduction. Generally, no significant effect on other TVA parameters or on tapping accuracy was found. Comparable goodness-of-fit measures were obtained for the TVA modeling data in single and dual tasks, indicating that tasks were executed in a qualitatively similar, continuous manner, although quantitatively less efficiently under dual- compared to single-task conditions. Taken together, our results show that the age-specific effects of motor-cognitive dual task interference are reflected by a stronger decline of VSTM storage capacity. They support an interpretation of VSTM as central attentional capacity, which is shared across visual uptake and concurrent motor performance. Capacity limits are reached earlier, and already under lower motor task complexity, in older compared to younger adults.

Somatosensory deficits

The analysis and interpretation of somatosensory information are performed by a complex network of brain areas located mainly in the parietal cortex. Somatosensory deficits are therefore a common impairment following lesions of the parietal lobe. This chapter summarizes the clinical presentation, examination, prognosis, and therapy of sensory deficits, along with current knowledge about the anatomy and function of the somatosensory system. We start by reviewing how somatosensory signals are transmitted to and processed by the parietal lobe, along with the anatomic and functional features of the somatosensory system. In this context, we highlight the importance of the thalamus for processing somatosensory information in the parietal lobe. We discuss typical patterns of somatosensory deficits, their clinical examination, and how they can be differentiated through a careful neurologic examination that allows the investigator to deduce the location and size of the underlying lesion. In the context of adaption and rehabilitation of somatosensory functions, we delineate the importance of somatosensory information for motor performance and the prognostic evaluation of somatosensory deficits. Finally, we review current rehabilitation approaches for directing cortical reorganization in the appropriate direction and highlight some challenging questions that are unexplored in the field.

Enhancement of face-sensitive ERPs in older adults induced by face recognition training

A common cognitive problem reported by older people is compromised face recognition, which is often paralleled by age-related changes in face-sensitive and memory-related components in event-related brain potentials (ERPs). We developed a new training using photorealistic caricatures based on evidence that caricatures are beneficial for people with compromised face processing. Twenty-four older participants (62-75 yrs, 13 female) completed 12 training sessions (3 per week, 60 min each) and 24 older participants (61-76 yrs, 12 female) acted as controls. Before and after training (or waiting), participants took part in a diagnostic test battery for face processing abilities, and in ERP experiments on face learning and recognition. Although performance improvements during the training provided little evidence for generalization to other face processing tasks, ERPs showed substantial training-related enhancements of face-sensitive ERPs. Specifically, we observed marked increases of the N170, P200 and N250 components, which may indicate training-induced enhancement of face detection and activation of identity-specific representations. Thus, neuronal correlates of face processing are plastic in older age, and can be modulated by caricature training.

Value of the eazyplex® CSF direct assay in rapid diagnosis of invasive meningococcal disease - Case report

There is a need for easy-to-use molecular assays for diagnosis of invasive meningococcal disease. Here, we report the rapid identification of Neisseria meningitidis in a cerebrospinal fluid sample from a patient with purulent meningitis using a commercially available loop-mediated isothermal amplification assay, resulting in a prompt de-escalation of the initial empiric antibiotic therapy.

Ultrasonography of the Vagus Nerve in Parkinson's Disease

Based on the topographic distribution of α-synuclein-enriched Lewy bodies, it has been hypothesized that Parkinson's disease may start in the gastrointestinal tract and gain access to the central nervous system via the vagus nerve. Since ultrasonography is a powerful tool to study peripheral nerve disturbances, we conducted ultrasonography of the vagus nerve in 32 patients with Parkinson's disease, 15 disease controls and 15 healthy controls. The cross-sectional area and echogenicity measured on transverse scans of the vagus nerve did not differ significantly between these groups. Therefore, the observed intraneuronal changes in Parkinson's disease are not associated with ultrasonographic disruptions of the vagus nerve integrity. HIGHLIGHTS We studied ultrasonography of the vagus nerve in 32 patients with Parkinson's disease and in 15 disease controls and 15 healthy controls.The sonographic cross-sectional area measured using high-frequency linear array transducers did not differ significantly between both groups.Ultrasonography of the vagal nerve does not reflect cellular damage caused by α-synuclein-enriched Lewy bodies in nerves of patients with Parkinson's disease.

The Use of Ostrich Eggs for In Ovo Research: Making Preclinical Imaging Research Affordable and Available

In ovo studies are a valuable option in preclinical research, but imaging studies are severely limited by the costs of dedicated equipment needed for small-sized eggs. We sought to verify the feasibility of using larger, ostrich, eggs (Struthio camelus) for imaging on the PET/CT scanners used for routine clinical investigations. Methods: Ostrich eggs were incubated until shortly before hatching, prepared for intravitelline venous injection of contrast medium or radiotracer, and imaged using native CT, contrast-enhanced CT, and PET/CT. Any technical adaptations that were needed to improve the outcome were noted. Results: Of the 34 eggs initially incubated, 12 became fully available for imaging of embryonal development. In ovo imaging with conventional PET/CT not only was feasible but also provided images of good quality, including on dynamic PET imaging. Conclusion: In ovo imaging with ostrich eggs and routine clinical scanners may allow broader application of this field of preclinical research, obviating costly dedicated equipment and reducing the number of animals needed for classic animal research. Further experiments are warranted to refine this novel approach, especially to reduce motion artifacts and improve monitoring of viability.

Impact of transcranial direct current stimulation on structural plasticity of the somatosensory system

While there is a growing body of evidence regarding the behavioral and neurofunctional changes in response to the longitudinal delivery of transcranial direct current stimulation (tDCS), there is limited evidence regarding its structural effects. Therefore, the present study was intended to investigate the effect of repeatedly applied anodal tDCS over the primary somatosensory cortex on the gray matter (GM) and white matter (WM) compartment of the brain. Structural tDCS effects were, moreover, related to effects evidenced by functional imaging and behavioral assessment. tDCS was applied over the course of 5 days in 25 subjects with concomitant assessment of tactile acuity of the right and left index finger as well as imaging at baseline, after the last delivery of tDCS and at follow-up 4 weeks thereafter. Irrespective of the stimulation condition (anodal vs. sham), voxel-based morphometry revealed a behaviorally relevant decrease of GM in the precuneus co-localized with a functional change of its activity. Moreover, there was a decrease in GM of the bilateral lingual gyrus and the right cerebellum. Diffusion tensor imaging analysis showed an increase of fractional anisotropy exclusively in the tDCS_anodal condition in the left frontal cortex affecting the final stretch of a somatosensory decision making network comprising the middle and superior frontal gyrus as well as regions adjacent to the genu of the corpus callosum. Thus, this is the first study in humans to identify structural plasticity in the GM compartment and tDCS-specific changes in the WM compartment in response to somatosensory learning.

Dysregulation of chemokine receptor expression and function in leukocytes from ALS patients

Amyotrophic lateral sclerosis (ALS) is rapidly progressive adult-onset motor neuron disease characterized by the neurodegeneration of both upper and lower motor neurons in the cortex and the spinal cord; the majority of patients succumb to respiratory failure. Although the etiology is not yet fully understood, there is compelling evidence that ALS is a multi-systemic disorder, with peripheral inflammation critically contributing to the disease process. However, the full extent and nature of this immunological dysregulation remains to be established, particularly within circulating blood cells. Therefore, the aim of the present study was to identify dysregulated inflammatory molecules in peripheral blood cells of ALS patients and analyze for functional consequences of the observed findings. To this end, we employed flow cytometry-based screening to quantify the surface expression of major chemokine receptors and integrins. A significantly increased expression of CXCR3, CXCR4, CCL2, and CCL5 was observed on T cells in ALS patients compared to healthy controls. Intriguingly, the expression was even more pronounced in patients with a slow progressive phenotype. To further investigate the functional consequences of this altered surface expression, we used a modified Boyden chamber assay to measure chemotaxis in ALS patient-derived lymphocytes. Interestingly, chemoattraction with the CXCR3-Ligand IP10 led to upregulated migratory behavior of ALS lymphocytes compared to healthy controls. Taken together, our data provides evidence for a functional dysregulation of IP10-directed chemotaxis in peripheral blood cells in ALS patients. However, whether the chemokine itself or its receptor CXCR3, or both, could serve as potential therapeutic targets in ALS requires further investigations.

Frataxin overexpression in Müller cells protects retinal ganglion cells in a mouse model of ischemia/reperfusion injury in vivo

Müller cells are critical for retinal function and neuronal survival but can become detrimental in response to retinal ischemia and increased oxidative stress. Elevated oxidative stress increases expression of the mitochondrial enzyme frataxin in the retina, and its overexpression is neuroprotective after ischemia. Whether frataxin expression in Müller cells might improve their function and protect neurons after ischemia is unknown. The aim of this study was to evaluate the effect of frataxin overexpression in Müller cells on neuronal survival after retinal ischemia/reperfusion in the mouse in vivo. Retinal ischemia/reperfusion was induced in mice overexpressing frataxin in Müller cells by transient elevation of intraocular pressure. Retinal ganglion cells survival was determined 14 days after lesion. Expression of frataxin, antioxidant enzymes, growth factors and inflammation markers was determined with qRT-PCR, Western blotting and immunohistochemistry 24 hours after lesion. Following lesion, there was a 65% increase in the number of surviving RGCs in frataxin overexpressing mice. Improved survival was associated with increased expression of the antioxidant enzymes Gpx1 and Sod1 as well as the growth factors Cntf and Lif. Additionally, microglial activation was decreased in these mice. Therefore, support of Müller cell function constitutes a feasible approach to reduce neuronal degeneration after ischemia.

Rapid increases in nitrogen oxides are associated with acute myocardial infarction: A case-crossover study

Aims High concentrations of air pollutants are associated with increased risk for myocardial infarction. The European Union has defined statutory limits for air pollutants based on upper absolute concentrations. We evaluated the association between rapid changes in air pollutants and the risk of myocardial infarction independently of absolute concentrations. Methods and results Using a hospital-based case-crossover study, effects of 24h changes of nitrogen oxides (NO_X/2), particulate matter (PM₁₀), and ozone on the risk of myocardial infarction was assessed in 693 patients. In the overall population, increases of NO_X of more than 20 µg/m³ within 24 h were associated with an increase in the risk of myocardial infarction by up to 121% (odds ratio (OR) 2.21, 95% confidence interval (CI) 1.19-4.08). Comparably, rapid increases of NO₂ of more than 8 µg/m³ tended to increase myocardial infarction risk by 73% (OR 1.73, 95% CI 0.91-3.28) while myocardial infarction risk decreased by 60% after a decrease of NO₂ concentration of more than 8 µg/m³ (OR 0.4, 95% CI 0.21-0.77), suggesting a close-to-linear association. While results for ozone concentrations were ambiguous, rapid change in PM₁₀ was not associated with myocardial infarction risk. Conclusion Dynamics and extent of increase in nitrogen oxide concentrations may be an independent risk factor for myocardial infarction. As there are currently no European Union statutory limits reflecting this dynamic variation of air pollutants on a daily basis, the results urgently call for confirming studies in different geographical regions to verify the observations.

Transcriptomic alterations during ageing reflect the shift from cancer to degenerative diseases in the elderly

Disease epidemiology during ageing shows a transition from cancer to degenerative chronic disorders as dominant contributors to mortality in the old. Nevertheless, it has remained unclear to what extent molecular signatures of ageing reflect this phenomenon. Here we report on the identification of a conserved transcriptomic signature of ageing based on gene expression data from four vertebrate species across four tissues. We find that ageing-associated transcriptomic changes follow trajectories similar to the transcriptional alterations observed in degenerative ageing diseases but are in opposite direction to the transcriptomic alterations observed in cancer. We confirm the existence of a similar antagonism on the genomic level, where a majority of shared risk alleles which increase the risk of cancer decrease the risk of chronic degenerative disorders and vice versa. These results reveal a fundamental trade-off between cancer and degenerative ageing diseases that sheds light on the pronounced shift in their epidemiology during ageing.

Ageing is associated with a pronounced shift in mortality from cancer to degenerative diseases. Here, the authors show that in concordance with this shift, conserved transcriptional alterations during ageing across four vertebrates align with degenerative diseases but are opposite to those in cancer.

Impact of chronic maternal stress during early gestation on maternal-fetal stress transfer and fetal stress sensitivity in sheep

Acute stress-induced reduction of uterine blood flow (UBF) is an indirect mechanism of maternal-fetal stress transfer during late gestation. Effects of chronic psychosocial maternal stress (CMS) during early gestation, as may be experienced by many working women, on this stress signaling mechanism are unclear. We hypothesized that CMS in sheep during early gestation augments later acute stress-induced decreases of UBF, and aggravates the fetal hormonal, cardiovascular, and metabolic stress responses during later development. Six pregnant ewes underwent repeated isolation stress (CMS) between 30 and 100 days of gestation (dGA, term: 150 dGA) and seven pregnant ewes served as controls. At 110 dGA, ewes were chronically instrumented and underwent acute isolation stress. The acute stress decreased UBF by 19% in both the CMS and control groups (p < .05), but this was prolonged in CMS versus control ewes (74 vs. 30 min, p < .05). CMS increased fetal circulating baseline and stress-induced cortisol and norepinephrine concentrations indicating a hyperactive hypothalamus-pituitary-adrenal (HPA)-axis and sympathetic-adrenal-medullary system. Increased fetal norepinephrine is endogenous as maternal catecholamines do not cross the placenta. Cortisol in the control but not in the CMS fetuses was correlated with maternal cortisol blood concentrations; these findings indicate: (1) no increased maternal-fetal cortisol transfer with CMS, (2) cortisol production in CMS fetuses when the HPA-axis is normally inactive, due to early maturation of the fetal HPA-axis. CMS fetuses were better oxygenated, without shift towards acidosis compared to the controls, potentially reflecting adaptation to repeated stress. Hence, CMS enhances maternal-fetal stress transfer by prolonged reduction in UBF and increased fetal HPA responsiveness.

DNA plasticity and damage in amyotrophic lateral sclerosis

The pathophysiology of amyotrophic lateral sclerosis (ALS) is particularly challenging due to the heterogeneity of its clinical presentation and the diversity of cellular, molecular and genetic peculiarities involved. Molecular insights unveiled several novel genetic factors to be inherent in both familial and sporadic disease entities, whose characterizations in terms of phenotype prediction, pathophysiological impact and putative prognostic value are a topic of current researches. However, apart from genetically well-defined high-confidence and other susceptibility loci, the role of DNA damage and repair strategies of the genome as a whole, either elicited as a direct consequence of the underlying genetic mutation or seen as an autonomous parameter, in the initiation and progression of ALS, and the different cues involved in either process are still incompletely understood. This mini review summarizes current knowledge on DNA alterations and counteracting DNA repair strategies in ALS pathology and discusses the putative role of unconventional DNA entities including transposable elements and extrachromosomal circular DNA in the disease process. Focus is set on SOD1-related pathophysiology, with extension to FUS, TDP-43 and C9ORF72 mutations. Advancing our knowledge in the field will contribute to an improved understanding of this relentless disease, for which therapeutic options others than symptomatic approaches are almost unavailable.

Sigma 1 receptor activation modifies intracellular calcium exchange in the G93AhSOD1 ALS model

Aberrations in intracellular calcium (Ca2+) have been well established within amyotrophic lateral sclerosis (ALS), a severe motor neuron disease. Intracellular Ca2+ concentration is controlled in part through the endoplasmic reticulum (ER) mitochondria Ca2+ cycle (ERMCC). The ER supplies Ca2+ to the mitochondria at close contacts between the two organelles, i.e. the mitochondria-associated ER membranes (MAMs). The Sigma 1 receptor (Sig1R) is enriched at MAMs, where it acts as an inter-organelle signaling modulator. However, its impact on intracellular Ca2+ at the cellular level remains to be thoroughly investigated. Here, we used cultured embryonic mice spinal neurons to investigate the influence of Sig1R activation on intracellular Ca2+ homeostasis in the presence of G93AhSOD1 (G93A), an established ALS-causing mutation. Sig1R expression was increased in G93A motor neurons relative to non-transgenic (nontg) controls. Furthermore, we demonstrated significantly reduced bradykinin-sensitive intracellular Ca2+ stores in G93A spinal neurons, which were normalized by the Sig1R agonist SA4503. Moreover, SA4503 accelerated cytosolic Ca2+ clearance following a) AMPAR activation by kainate and b) IP3R-mediated ER Ca2+ release following bradykinin stimulation in both genotypes. PRE-084 (another Sig1R agonist) did not exert any significant effects on cytosolic Ca2+. Both Sig1R expression and functionality were altered by the G93A mutation, indicating the centrality of Sig1R in ALS pathology. Here, we showed that intracellular Ca2+ shuttling can be manipulated by Sig1R activation, thus demonstrating the value of using the pharmacological manipulation of Sig1R to understand Ca2+ homeostasis.

Tissue-, sex-, and age-specific DNA methylation of rat glucocorticoid receptor gene promoter and insulin-like growth factor 2 imprinting control region

Tissue-, sex-, and age-specific epigenetic modifications such as DNA methylation are largely unknown. Changes in DNA methylation of the glucocorticoid receptor gene (NR3C1) and imprinting control region (ICR) of IGF2 and H19 genes during the lifespan are particularly interesting since these genes are susceptible to epigenetic modifications by prenatal stress or malnutrition. They are important regulators of development and aging. Methylation changes of NR3C1 affect glucocorticoid receptor expression, which is associated with stress sensitivity and stress-related diseases predominantly occurring during aging. Methylation changes of IGF2/H19 affect growth trajectory and nutrient use with risk of metabolic syndrome. Using a locus-specific approach, we characterized DNA methylation patterns of different Nr3c1 promoters and Igf2/H19 ICR in seven tissues of rats at 3, 9, and 24 mo of age. We found a complex pattern of locus-, tissue-, sex-, and age-specific DNA methylation. Tissue-specific methylation was most prominent at the shores of the Nr3c1 CpG island (CGI). Sex-specific differences in methylation peaked at 9 mo. During aging, Nr3c1 predominantly displayed hypomethylation mainly in females and at shores, whereas hypermethylation occurred within the CGI. Igf2/H19 ICR exhibited age-related hypomethylation occurring mainly in males. Methylation patterns of Nr3c1 in the skin correlated with those in the cortex, hippocampus, and hypothalamus. Skin may serve as proxy for methylation changes in central parts of the hypothalamic-pituitary-adrenal axis and hence for vulnerability to stress- and age-associated diseases. Thus, we provide in-depth insight into the complex DNA methylation changes of rat Nr3c1 and Igf2/H19 during aging that are tissue and sex specific.

Adult hippocampal neurogenesis poststroke: More new granule cells but aberrant morphology and impaired spatial memory

Stroke significantly stimulates neurogenesis in the adult dentate gyrus, though the functional role of this postlesional response is mostly unclear. Recent findings suggest that newborn neurons generated in the context of stroke may fail to correctly integrate into pre-existing networks. We hypothesized that increased neurogenesis in the dentate gyrus following stroke is associated with aberrant neurogenesis and impairment of hippocampus-dependent memory. To address these questions we used the middle cerebral artery occlusion model (MCAO) in mice. Animals were housed either under standard conditions or with free access to running wheels. Newborn granule cells were labelled with the thymidine analoque EdU and retroviral vectors. To assess memory performance, we employed a modified version of the Morris water maze (MWM) allowing differentiation between hippocampus dependent and independent learning strategies. Newborn neurons were morphologically analyzed using confocal microscopy and Neurolucida system at 7 weeks. We found that neurogenesis was significantly increased following MCAO. Animals with MCAO needed more time to localize the platform and employed less hippocampus-dependent search strategies in MWM versus controls. Confocal studies revealed an aberrant cell morphology with basal dendrites and an ectopic location (e.g. hilus) of new granule cells born in the ischemic brain. Running increased the number of new neurons but also enhanced aberrant neurogenesis. Running, did not improve the general performance in the MWM but slightly promoted the application of precise spatial search strategies. In conclusion, ischemic insults cause hippocampal-dependent memory deficits which are associated with aberrant neurogenesis in the dentate gyrus indicating ischemia-induced maladaptive plasticity in the hippocampus.

DNA strand breaks and TDP-43 mislocation are absent in the murine hSOD1G93A model of amyotrophic lateral sclerosis in vivo and in vitro

Mutations in the human Cu/Zn superoxide dismutase type-1 (hSOD1) gene are common in familial amyotrophic lateral sclerosis (fALS). The pathophysiology has been linked to, e.g., organelle dysfunction, RNA metabolism and oxidative DNA damage conferred by SOD1 malfunction. However, apart from metabolically evoked DNA oxidation, it is unclear whether severe genotoxicity including DNA single-strand breaks (SSBs) and double-strand breaks (DSBs), originates from loss of function of nuclear SOD1 enzyme. Factors that endogenously interfere with DNA integrity and repair complexes in hSOD1-mediated fALS remain similarly unexplored. In this regard, uncontrolled activation of transposable elements (TEs) might contribute to DNA disintegration and neurodegeneration. The aim of this study was to elucidate the role of the fALS-causing hSOD1^G93A mutation in the generation of severe DNA damage beyond well-characterized DNA base oxidation. Therefore, DNA damage was assessed in spinal tissue of hSOD1^G93A-overexpressing mice and in corresponding motor neuron-enriched cell cultures in vitro. Overexpression of the hSOD1^G93A locus did not change the threshold for severe DNA damage per se. We found that levels of SSBs and DSBs were unaltered between hSOD1^G93A and control conditions, as demonstrated in post-mitotic motor neurons and in astrocytes susceptible to replication-dependent DNA breakage. Analogously, parameters indicative of DNA damage response processes were not activated in vivo or in vitro. Evidence for a mutation-related elevation in TE activation was not detected, in accordance with the absence of TAR DNA binding protein 43 (TDP-43) proteinopathy in terms of cytoplasmic mislocation or nuclear loss, as nuclear TDP-43 is supposed to silence TEs physiologically. Conclusively, the superoxide dismutase function of SOD1 might not be required to preserve DNA integrity in motor neurons, at least when the function of TDP-43 is unaltered. Our data establish a foundation for further investigations addressing functional TDP-43 interaction with ALS-relevant genetic mutations.

Automatic affective responses towards the bed in patients with primary insomnia: evidence for a negativity bias

Ruminating about sleep problems and negatively valenced thinking play a key role in the maintenance of sleep complaints in patients with insomnia. Based on associative learning principles, we hypothesized that repeated co-occurrence of negative thoughts (unconditioned stimulus) and the bedroom environment (conditioned stimulus) results in automatic negative affective responses towards the bed (conditioned response). Twenty-two insomniacs and 22 good sleepers performed a Single-Target Implicit Association Test measuring the strength of automatically triggered affective responses towards the bed. Results revealed a significant group difference, indicating a stronger negative affective response towards the bed in patients with insomnia. No correlations were found between the strength of negative affective responses towards the bed and subjective measures of sleep quality. As it might increase the stress experience further during bedtime, automatic negative responses towards the bed are likely to represent an additional factor accounting for the development and maintenance of sleep disorders and represent a potential target for therapeutic interventions.