The AUSTRAL VLBI observing program.

The AUSTRAL observing program was started in 2011, performing geodetic and astrometric very long baseline interferometry (VLBI) sessions using the new Australian AuScope VLBI antennas at Hobart, Katherine, and Yarragadee, with contribution from the Warkworth (New Zealand) 12 m and Hartebeesthoek (South Africa) 15 m antennas to make a southern hemisphere array of telescopes with similar design and capability. Designed in the style of the next-generation VLBI system, these small and fast antennas allow for a new way of observing, comprising higher data rates and more observations than the standard observing sessions coordinated by the International VLBI Service for Geodesy and Astrometry (IVS). In this contribution, the continuous development of the AUSTRAL sessions is described, leading to an improvement of the results in terms of baseline length repeatabilities by a factor of two since the start of this program. The focus is on the scheduling strategy and increased number of observations, aspects of automated operation, and data logistics, as well as results of the 151 AUSTRAL sessions performed so far. The high number of the AUSTRAL sessions makes them an important contributor to VLBI end-products, such as the terrestrial and celestial reference frames and Earth orientation parameters. We compare AUSTRAL results with other IVS sessions and discuss their suitability for the determination of baselines, station coordinates, source coordinates, and Earth orientation parameters.

Heart-rate variability (HRV) in the ECG trace of routine EEGs: fast monitoring for the anticholinergic effects of clozapine and olanzapine?

Drug monitoring in psychiatry usually serves psychoactive drug plasma concentration measurement. Anticholinergic properties offer a faster approach to monitoring pharmacodynamic intraindividual effects of the drug by measuring their effects on heart rate variability (HRV), which is sympathetically and parasympathetically controlled via cholinergic synapses. The plasma concentrations of the atypical antipsychotics clozapine and olanzapine correlated with parameters of HRV in 59 patients suffering from schizophrenia or schizoaffective disorder. HRV during 4 minutes at rest was extracted from the ECG trace of a routine digital EEG registration in addition to blood sampling for plasma concentration measurement (HPLC method). We calculated sympathetically and parasympathetically controlled heart frequency bands (low, medium and high frequency) and other HRV parameters, coefficient of variation (CV), and root mean square of successive differences (RMSSD). All HRV parameters were significantly more impaired in clozapine patients (n = 33, mean clozapine plasma concentration 331 +/- 294 ng/ml) than in olanzapine patients (n = 26, mean olanzapine plasma concentration 42 +/- 32 ng/ml) and demonstrated 1.7 - 4.8 times the cardiac anticholinergic properties of clozapine in vivo. 14 out of 14 patients with a CV beyond 3.2 % had clozapine plasma concentrations below the proposed optimal therapeutic concentration of 350 ng/ml. All HRV parameters were inversely and significantly correlated with the clozapine plasma concentrations (such as lgCV: r = - 0.73, p < 0.001) and, to a lesser extent, with the olanzapine plasma concentrations (lgCV r = - 0.44, p < 0.05). These results underline the potential clinical value of HRV parameter extraction from routine ECGs in predicting plasma concentrations and objective individual neurocardiac effects of drugs with anticholinergic properties.

Dynamic regulation of EEG power and coherence is lost early and globally in probable DAT.

Electroencephalographic (EEG) findings in dementia of Alzheimer type (DAT) include slowing of alpha frequency, loss of alpha band power, increased theta and delta power and reduced coherence. Here it is evaluated whether a) EEG acquisition during different functional states facilitates the detection of DAT-associated EEG changes, and b) EEG changes in mild DAT are topographically confined or global. Power spectra and coherence of EEGs from 29 patients with mild probable DAT and 28 age- and sex-matched controls were compared during three cognitive states. Group differences in power spectra and coherence were largest during resting with eyes open, yielding a 77% correct classification result. Already in early stages of probable DAT, EEG changes were topographically wide-spread. The task-related up- and down-regulation of power and coherence was impaired already in mild probable DAT. We propose to augment clinical EEG assessment by including a quantitative analysis of the dynamic power and coherence changes from rest, eyes closed to eyes open in suspected DAT.

Leptin attenuates cardiac contraction in rat ventricular myocytes. Role of NO.

Obesity is commonly associated with impaired myocardial contractile function. However, a direct link between these 2 states has not yet been established. There has been an indication that leptin, the product of the human obesity gene, may play a role in obesity-related metabolic and cardiovascular dysfunctions. The purpose of this study was to determine whether leptin exerts any direct cardiac contractile action that may contribute to altered myocardial function. Ventricular myocytes were isolated from adult male Sprague-Dawley rats. Contractile responses were evaluated by use of video-based edge detection. Contractile properties analyzed in cells electrically stimulated at 0.5 Hz included peak shortening, time to 90% peak shortening, time to 90% relengthening, and fluorescence intensity change. Leptin exhibited a dose-dependent inhibition in myocyte shortening and intracellular Ca(2+) change, with maximal inhibitions of 22.4% and 26.2%, respectively. Pretreatment with the NO synthase inhibitor N:(omega)-nitro-L-arginine methyl ester (L-NAME, 100 micromol/L) blocked leptin-induced inhibition of both peak shortening and fluorescence intensity change. Leptin also stimulated NO synthase activity in a time- and concentration-dependent manner, as reflected in the dose-related increase in NO accumulation in these cells. Addition of an NO donor (S-nitroso-N-acetyl-penicillamine [SNAP]) to the medium mimicked the effects of leptin administration. In summary, this study demonstrated a direct action of leptin on cardiomyocyte contraction, possibly through an increased NO production. These data suggest that leptin may play a role in obesity-related cardiac contractile dysfunction.

Pain sensitivity, cerebral laterality, and negative affect.

The right hemisphere is assumed to play a unique role for pain sensitivity and negative affect. Pressure pain thresholds were assessed daily in eight right-handed participants over a 6-week period in order to obtain reliable measures of pain sensitivity unaffected by situational influences. In an additional session, cerebral laterality was assessed with behavioral and an EEG measures. Psychometric measures were used to examine emotionality (depression, neuroticism). Pain thresholds were lower on the left compared with the right hand, and pain thresholds increased within the first 3-measurement weeks. Enhanced pain sensitivity as reflected in weekly pain threshold was associated with a increased right frontal compared with left frontal brain activity as indicated by EEG, with a left-visual field advantage in the perception of emotional faces, and with increased negative affect (depression, neuroticism). In addition, a significant positive correlation between a relatively increased right frontal brain activity and depression was found. Correlations between pain thresholds and 'non-emotional' laterality measures (central or parietal EEG asymmetry, dichotic consonant-vocal-recall test) were not significant. We conclude that a right frontal brain hyperactivity might be a biological marker for enhanced pain sensitivity and negative affect.

Pressure pain thresholds asymmetry in left- and right-handers: Associations with behavioural measures of cerebral laterality.

Pressure pain threshold (PPT) asymmetry of the left and right third digits was assessed in 12 right-handed and 12 left-handed subjects using an automatised pressure algometer. A clear PPT asymmetry was found in right-handed participants, while left-handed participants revealed no PPT asymmetry. The PPT asymmetry of right-handed participants was due to a reduced PPT or increased pain sensitivity at the left hand. Behavioural laterality tests revealed a right ear or left hemisphere advantage for the processing of verbal material (consonant-vocal syllables) and a left visual field or right hemisphere advantage for the processing of emotional faces in all participants. PPT asymmetry was not associated with cerebral laterality assessed with these tests. We conclude that PPT asymmetry is associated with handedness, but neither PPT asymmetry nor handedness are closely associated with measures of cerebral laterality. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.