Method for quantifying arousal and consciousness in healthy states and severe brain injury via EEG-based measures of corticothalamic physiology.

BACKGROUND: Characterization of normal arousal states has been achieved by fitting predictions of corticothalamic neural field theory (NFT) to electroencephalographic (EEG) spectra to yield relevant physiological parameters. NEW METHOD: A prior fitting method is extended to distinguish conscious and unconscious states in healthy and brain injured subjects by identifying additional parameters and clusters in parameter space. RESULTS: Fits of NFT predictions to EEG spectra are used to estimate neurophysiological parameters in healthy and brain injured subjects. Spectra are used from healthy subjects in wake and sleep and from patients with unresponsive wakefulness syndrome, in a minimally conscious state (MCS), and emerged from MCS. Subjects cluster into three groups in parameter space: conscious healthy (wake and REM), sleep, and brain injured. These are distinguished by the difference X-Y between corticocortical (X) and corticothalamic (Y) feedbacks, and by mean neural response rates α and ß to incoming spikes. X-Y tracks consciousness in healthy individuals, with smaller values in wake/REM than sleep, but cannot distinguish between brain injuries. Parameters α and ß differentiate deep sleep from wake/REM and brain injury. COMPARISON WITH EXISTING METHODS: Other methods typically rely on laborious clinical assessment, manual EEG scoring, or evaluation of measures like Φ from integrated information theory, for which no efficient method exists. In contrast, the present method can be automated on a personal computer. CONCLUSION: The method provides a means to quantify consciousness and arousal in healthy and brain injured subjects, but does not distinguish subtypes of brain injury.

Function-structure connectivity in patients with severe brain injury as measured by MRI-DWI and FDG-PET.

A vast body of literature exists showing functional and structural dysfunction within the brains of patients with disorders of consciousness. However, the function (fluorodeoxyglucose FDG-PET metabolism)-structure (MRI-diffusion-weighted images; DWI) relationship and how it is affected in severely brain injured patients remains ill-defined. FDG-PET and MRI-DWI in 25 severely brain injured patients (19 Disorders of Consciousness of which 7 unresponsive wakefulness syndrome, 12 minimally conscious; 6 emergence from minimally conscious state) and 25 healthy control subjects were acquired here. Default mode network (DMN) function-structure connectivity was assessed by fractional anisotropy (FA) and metabolic standardized uptake value (SUV). As expected, a profound decline in regional metabolism and white matter integrity was found in patients as compared with healthy subjects. Furthermore, a function-structure relationship was present in brain-damaged patients between functional metabolism of inferior-parietal, precuneus, and frontal regions and structural integrity of the frontal-inferiorparietal, precuneus-inferiorparietal, thalamo-inferioparietal, and thalamofrontal tracts. When focusing on patients, a stronger relationship between structural integrity of thalamo-inferiorparietal tracts and thalamic metabolism in patients who have emerged from the minimally conscious state as compared with patients with disorders of consciousness was found. The latter finding was in line with the mesocircuit hypothesis for the emergence of consciousness. The findings showed a positive function-structure relationship within most regions of the DMN. Hum Brain Mapp 37:3707-3720, 2016. © 2016 Wiley Periodicals, Inc.

Infrared spectroscopy of the lower stratosphere with a balloon-borne cryogenic Fourier spectrometer.

The IR limb emission of the lower stratosphere has been measured using a balloon-borne liquid nitrogencooled Michelson interferometer with liquid helium-cooled Si:Ga detectors. Portions of the thermal emission spectrum have been recorded between 650 and 2000 cm(-1) with an unapodized spectral resolution of 0.03 cm(-1). This is the highest spectral resolution limb emission thus far obtained. A preliminary description is given of these data along with a discussion of the significant features. Species identified to date include CO(2), O(3), CFCl(3), CF(2)Cl(2), H(2)O, CH(4), HNO(3), N(2)O, NO(2), and ClONO(2). A tentative identification is made for NO, representing the first direct spectroscopic detection of NO in emission.

Cytotoxicity of Echinococcus granulosus cyst fluid in vitro.

In a cytotoxicity assay, using rat spleen cells as target cells, Echinococcus granulosus cyst fluid from cattle exerted a marked degree of cytotoxicity in vitro. When trypan blue exclusion or [3H]thymidine incorporation by concanavalin A stimulated spleen cells was used as a measure of cell viability, dialyzed cyst fluid showed maximum cell destruction up to a 1:8 dilution. The effect was dose and time dependent, cells being affected by 24 h after exposure to cyst fluid. The components responsible for cytotoxicity of cyst fluid were heat stable and could be recovered using gel chromatography on Sephadex G 50 and G 15 as a single low molecular weight fraction. It is assumed that the toxic products released by the living parasite can readily penetrate through the cyst wall into the surrounding host tissue. The interference of such substances with immunocompetent cells might account for the long-term survival of the parasite in the intermediate host.

[Simple method for obtaining Toxocara canis antigen for the indirect immunofluorescence technic]. / Eine einfache Methode zur Gewinnung von Toxocara canis-Antigen für die indirekte Immunofluoreszenz-Technik

A simple method for the preparation of Toxocara canis antigen for the indirect immunofluorescent test is described: Embryonated Toxocara eggs are treated for 12 hours at room temperature with a 1:1 mixture of 2% NaHO and sodium hypochlorite (NaClO) solution with a concentration of 2% free chlorine in order to remove the outer layers of the egg shells. The larvae which are still enclosed in the lipid membrane are freed by mild ultrasonic treatment. Thereafter, the suspension of larvae is washed and purified in a modified Baermann apparatus. In this way large numbers of larvae in pure suspension were gained and used for the production of frozen sections for the indirect immunofluorescent test. Rabbits and mice experimentally infected with embryonated Toxocara canis eggs showed a positive serological reaction (titers between 1/10 to 1/320) in this test with Toxocara larvae as antigen, while in uninfected control animals no antibodies could be detected. The larval antigen exhibited only a weak cross reaction with sera of animals infected with Ascaris suum eggs.