Large-scale characterization of the microvascular geometry in development and disease by tissue clearing and quantitative ultramicroscopy

Three-dimensional assessment of optically cleared, entire organs and organisms has recently become possible by tissue clearing and selective plane illumination microscopy (“ultramicroscopy”). Resulting datasets can be highly complex, encompass over a thousand images with millions of objects and data of several gigabytes per acquisition. This constitutes a major challenge for quantitative analysis. We have developed post-processing tools to quantify millions of microvessels and their distribution in three-dimensional datasets from ultramicroscopy and demonstrate the capabilities of our pipeline within entire mouse brains and embryos. Using our developed acquisition, segmentation, and analysis platform, we quantify physiological vascular networks in development and the healthy brain. We compare various geometric vessel parameters (e.g. vessel density, radius, tortuosity) in the embryonic spinal cord and brain as well as in different brain regions (basal ganglia, corpus callosum, cortex). White matter tract structures (corpus callosum, spinal cord) showed lower microvascular branch densities and longer vessel branch length compared to grey matter (cortex, basal ganglia). Furthermore, we assess tumor neoangiogenesis in a mouse glioma model to compare tumor core and tumor border. The developed methodology allows rapid quantification of three-dimensional datasets by semi-automated segmentation of fluorescently labeled objects with conventional computer hardware. Our approach can aid preclinical investigations and paves the way towards “quantitative ultramicroscopy”.     

Brief Report: Specificity of Interpersonal Synchrony Deficits to Autism Spectrum Disorder and Its Potential for Digitally Assisted Diagnostics

Journal of Autism and Developmental Disorders - Reliably diagnosing autism spectrum disorders (ASD) in adulthood poses a challenge to clinicians due to the absence of specific diagnostic markers....     

Impact of dynamic bottom-up features and top-down control on the visual exploration of moving real-world scenes in hemispatial neglect

Patients with hemispatial neglect are severely impaired in orienting their attention to contralesional hemispace. Although motion is one of the strongest attentional cues in humans, it is still unknown how neglect patients visually explore their moving real-world environment. We therefore recorded eye movements at bedside in 19 patients with hemispatial neglect following acute right hemisphere stroke, 14 right-brain damaged patients without neglect and 21 healthy control subjects. Videos of naturalistic real-world scenes were presented first in a free viewing condition together with static images, and subsequently in a visual search condition. We analyzed number and amplitude of saccades, fixation durations and horizontal fixation distributions. Novel computational tools allowed us to assess the impact of different scene features (static and dynamic contrast, colour, brightness) on patients' gaze. Independent of the different stimulus conditions, neglect patients showed decreased numbers of fixations in contralesional hemispace (ipsilesional fixation bias) and increased fixation durations in ipsilesional hemispace (disengagement deficit). However, in videos left-hemifield fixations of neglect patients landed on regions with particularly high dynamic contrast. Furthermore, dynamic scenes with few salient objects led to a significant reduction of the pathological ipsilesional fixation bias. In visual search, moving targets in the neglected hemifield were more frequently detected than stationary ones. The top-down influence (search instruction) could neither reduce the ipsilesional fixation bias nor the impact of bottom-up features. Our results provide evidence for a strong impact of dynamic bottom-up features on neglect patients' scanning behaviour. They support the neglect model of an attentional priority map in the brain being imbalanced towards ipsilesional hemispace, which can be counterbalanced by strong contralateral motion cues. Taking into account the lack of top-down control in neglect patients, bottom-up stimulation with moving real-world stimuli may be a promising candidate for future neglect rehabilitation schemes.     

Increased S100B+ NK cell counts in acutely ill schizophrenia patients are correlated with the free cortisol index, but not with S100B serum levels

Several studies have provided evidence for increased S100B serum concentrations in schizophrenia. The pathophysiological significance of this finding is still uncertain because S100B is involved in many cellular mechanisms and is not astrocyte-specific as was previously assumed. S100B is also expressed by subsets of CD3+ CD8+ T cells and natural killer (NK) cells and may therefore be linked to the immune hypothesis of schizophrenia. We have quantified S100B+ CD3+ CD8+ T cells and NK cells by flow cytometry in the peripheral blood of 26 acutely ill schizophrenia cases and 32 matched controls. In parallel, S100B concentrations and the free cortisol index (FCI), a surrogate marker for stress axis activity, were determined in serum samples from the same blood draw. Psychopathology was monitored using the Positive and Negative Syndrome Scale (PANSS). The patient group had increased S100B+ NK cell counts (P=0.045), which correlated with the FCI (r=0.299, P=0.026) but not with the PANSS or the elevated (P=0.021) S100B serum concentrations. S100B+ CD3+ CD8+ T cell counts were not significantly changed in the patient group and did neither correlate with the FCI and PANSS, nor with S100B serum concentrations. In conclusion, despite the observation of an increase in S100B+ NK cells in schizophrenia patients, the lack of a correlation with serum S100B concentrations suggests that these cells are probably not a major source of S100B in the blood of schizophrenia patients. Notably, elevated S100B+ NK cell counts may be linked with stress axis activation.     

Type and frequency of IDH1 and IDH2 mutations are related to astrocytic and oligodendroglial differentiation and age: a study of 1,010 diffuse gliomas

Somatic mutations in the IDH1 gene encoding cytosolic NADP+-dependent isocitrate dehydrogenase have been shown in the majority of astrocytomas, oligodendrogliomas and oligoastrocytomas of WHO grades II and III. IDH2 encoding mitochondrial NADP+-dependent isocitrate dehydrogenase is also mutated in these tumors, albeit at much lower frequencies. Preliminary data suggest an importance of IDH1 mutation for prognosis showing that patients with anaplastic astrocytomas, oligodendrogliomas and oligoastrocytomas harboring IDH1 mutations seem to fare much better than patients without this mutation in their tumors. To determine mutation types and their frequencies, we examined 1,010 diffuse gliomas. We detected 716 IDH1 mutations and 31 IDH2 mutations. We found 165 IDH1 (72.7%) and 2 IDH2 mutations (0.9%) in 227 diffuse astrocytomas WHO grade II, 146 IDH1 (64.0%) and 2 IDH2 mutations (0.9%) in 228 anaplastic astrocytomas WHO grade III, 105 IDH1 (82.0%) and 6 IDH2 mutations (4.7%) in 128 oligodendrogliomas WHO grade II, 121 IDH1 (69.5%) and 9 IDH2 mutations (5.2%) in 174 anaplastic oligodendrogliomas WHO grade III, 62 IDH1 (81.6%) and 1 IDH2 mutations (1.3%) in 76 oligoastrocytomas WHO grade II and 117 IDH1 (66.1%) and 11 IDH2 mutations (6.2%) in 177 anaplastic oligoastrocytomas WHO grade III. We report on an inverse association of IDH1 and IDH2 mutations in these gliomas and a non-random distribution of the mutation types within the tumor entities. IDH1 mutations of the R132C type are strongly associated with astrocytoma, while IDH2 mutations predominantly occur in oligodendroglial tumors. In addition, patients with anaplastic glioma harboring IDH1 mutations were on average 6 years younger than those without these alterations.     

High resolution ultrasound in posterior interosseous nerve syndrome

Introduction: Posterior interosseous nerve (PIN) syndrome is a rare compression neuropathy of the PIN in the region of the supinator muscle, most common by the arcade of Frohse. We aimed to specify ultrasonographic findings in patients with PIN syndrome in comparison to healthy volunteers. Methods: Ultrasound images and clinical data of 13 patients with PIN syndrome confirmed by neurological examination and electrophysiological testing were evaluated retrospectively. Anteroposterior nerve diameters measured at the arcade of Frohse were compared with those of 20 healthy volunteers. The echotexture and the presence of a caliber change of the PIN were additionally assessed. Results: Enlargement of the PIN was seen in all patients with PIN syndrome, but not in volunteers (statistically significant difference in mean diameter P < 0.05). Furthermore, edema and caliber change of the PIN were present in all patients. Conclusions: High‐resolution ultrasound allows for differentiation between patients with PIN syndrome and healthy volunteers. Muscle Nerve 49 : 35–39, 2014     

Hereditary Orotic Aciduria: Evidence for a Structural Gene Mutation

Orotic aciduria is a rare autosomal recessive disease in man due to a deficiency of orotate phosphoribosyltransferase (EC 2.4.2.10; orotidine-5′-phosphate:pyrophosphate phosphoribosyltransferase) and orotidine-5′-phosphate decarboxylase (EC 4.1.1.23; orotidine-5′-phosphate carboxy-lyase). We have compared certain physicochemical properties of orotidine-5′-phosphate decarboxylase from normal and mutant fibroblasts grown under identical conditions. Orotidine-5′-phosphate decarboxylase from homozygous mutant cells was more thermolabile and exhibited a different electrophoretic mobility when compared to the enzyme from normal cells; orotidine-5′-phosphate decarboxylase from one heterozygous cell strain exhibited an intermediate thermolability while the other heterozygote displayed a thermal inactivation curve indistinguishable from normal. The enzyme from both normal and mutant cells exhibited biphasic kinetics with the same apparent Michaelis constants. These data suggest that the molecular defect in the enzyme of this patient with orotic aciduria is due to a mutation in a gene that affects the structure of either orotate phosphoribosyltransferase or orotidine-5′-phosphate decarboxylase and cannot be attributed to a mutation in a regulatory gene, as previously suggested.     

Assessment of depth perception using psychophysical thresholds and stereoscopically evoked brain activity

Dynamic random-dot stereograms (dRDS) elicit brain activity generated exclusively by cortical neurons sensitive to binocular horizontal disparity. We studied 20 adults with stereovision deficiency but otherwise normal vision. Psychophysical thresholds were determined with static RDS and with the three-rod experiment. VEP was recorded from seven occipital channels. Stimuli were presented on a monitor by dRDS as stereoscopic checkerboard patterns that moved in depth with 8 depth reversals per second. Horizontal disparity ranged from 7 to 24.5 min of arc. Stimuli were displayed at the center, or in the left or right half field. We determined electrophysiological thresholds as well as the disparity where largest responses occurred. Subjective and electrophysiological thresholds showed a significant positive correlation. In addition, the right visual field was more sensitive to dRDS stimuli than other locations. Squint angle was related to the disparity thresholds. Our data illustrate correlations between clinical symptoms, perceptual deficiency, and VEP parameters.