Epidermal growth factor (EGF) stimulation of cultured brain cells. I. Enhancement of the developmental increase in glial enzymatic activity.

Serum-free aggregating cell cultures of fetal rat telencephalon grown in the presence of 3 ng/ml (5 X 10(-10) M) epidermal growth factor (EGF) until day 12 showed 2- to 3-fold increased activities in the two glial enzymes, glutamine synthetase (GLU-S) and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase). This effect was concentration-dependent, with maximal stimulation in cultures treated daily with 3 ng/ml EGF. Addition of EGF during the first 10 culture days was sufficient to produce a maximal stimulation of both GLU-S and CNPase on day 19, whereas treatments starting on day 12 were ineffective. The stimulation of GLU-S preceded that of CNPase. The EGF-induced increase in GLU-S activity was not directly dependent on the presence of insulin, triiodothyronine, or hydrocortisone in the medium, whereas insulin was required for the stimulation of CNPase. A single dose of 5 ng/ml EGF on day 2 caused a slight but significant decrease in DNA synthesis after day 6. The present results indicate that in serum-free aggregating cell cultures of fetal rat telencephalon EGF partially inhibits DNA synthesis, and stimulates an early step in glial differentiation.

Ambulatory monitoring of physical activities in patients with Parkinson's disease.

A new ambulatory method of monitoring physical activities in Parkinson's disease (PD) patients is proposed based on a portable data-logger with three body-fixed inertial sensors. A group of ten PD patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) and ten normal control subjects followed a protocol of typical daily activities and the whole period of the measurement was recorded by video. Walking periods were recognized using two sensors on shanks and lying periods were detected using a sensor on trunk. By calculating kinematics features of the trunk movements during the transitions between sitting and standing postures and using a statistical classifier, sit-to-stand (SiSt) and stand-to-sit (StSi) transitions were detected and separated from other body movements. Finally, a fuzzy classifier used this information to detect periods of sitting and standing. The proposed method showed a high sensitivity and specificity for the detection of basic body postures allocations: sitting, standing, lying, and walking periods, both in PD patients and healthy subjects. We found significant differences in parameters related to SiSt and StSi transitions between PD patients and controls and also between PD patients with and without STN-DBS turned on. We concluded that our method provides a simple, accurate, and effective means to objectively quantify physical activities in both normal and PD patients and may prove useful to assess the level of motor functions in the latter.

The neuronal adhesion protein D2 in differentiating aggregates of brain cells.

The D2-protein is a high molecular weight protein involved in interneuronal adhesion. The concentration of D2-protein was measured both in aggregates of fetal rat telencephalic cells cultured in a chemically defined medium and in developing forebrain. Both the concentration of the D2-protein and the degree of sialylation were changed in the cultures in parallel with the corresponding values obtained from postnatal forebrain. In the cultures the highest specific concentration of D2-protein was observed after 12 days in culture. This value was 2.7 times higher than the average value of adult rat forebrain. Antibodies to D2-protein have previously been shown to inhibit fasciculation of neuritic fibers extending from cultured explants of sympathetic ganglia. We investigated the effect of such antibodies on the differentiation of aggregating telencephalic cells. By adding surplus antibodies to the cultures from day 11 to day 16 we were able to decrease the specific concentration of D2-protein on the neurons by 53% measured at day 19. The decrease was not compensated fully even after further 10 days in the culture. Although the concentration of D2-protein was decreased during the period of synaptogenesis no change was found in the specific concentration of a marker of mature synapses, the D3-protein. Thus, in this culture system synaptogenesis could proceed to an unimpaired extent in the presence of a decreased concentration of a putatively involved adhesion molecule. However, the specific concentration of two markers of myelination, 2',3'-cyclic nucleotide 3'-phosphodiesterase and myelin basic protein, were both increased, suggesting an antibody-induced stimulation of myelination in the cultured aggregates.

A new paradigm of neuromuscular electrical stimulation for the quadriceps femoris muscle.

PURPOSE: Neuromuscular electrical stimulation (NMES) with large electrodes and multiple current pathways (m-NMES) has recently been proposed as a valid alternative to conventional NMES (c-NMES) for quadriceps muscle (re)training. The main aim of this study was to compare discomfort, evoked force and fatigue between m-NMES and c-NMES of the quadriceps femoris muscle in healthy subjects. METHODS: Ten healthy subjects completed two experimental sessions (c-NMES and m-NMES), that were randomly presented in a cross-over design. Maximal electrically evoked force at pain threshold, self-reported discomfort at different levels of evoked force, and fatigue-induced force declines during and following a series of 20 NMES contractions were compared between c-NMES and m-NMES. RESULTS: m-NMES resulted in greater evoked force (P < 0.05) and lower discomfort in comparison to c-NMES (P < 0.05-0.001), but fatigue time course and magnitude did not differ between the two conditions. CONCLUSIONS: The use of quadriceps m-NMES appears legitimate for (re)training purposes because it generated stronger contractions and was less discomfortable than c-NMES (due to multiple current pathways and/or lower current density with larger electrodes).

Transcutaneous carbon dioxide tension in newborn infants: reliability and safety of continuous 24-hour measurement at 42 degrees C.

In 58 newborn infants a new iridium oxide sensor was evaluated for transcutaneous carbon dioxide (tcPCO2) monitoring at 42 degrees C with a prolonged fixation time of 24 hours. The correlation of tcPCO2 (y; mm Hg) v PaCO2 (x; mm Hg) for 586 paired values was: y = 4.6 + 1.45x; r = .89; syx = 6.1 mm Hg. The correlation was not influenced by the duration of fixation. The transcutaneous sensor detected hypocapnia (PaCO2 less than 35 mm Hg) in 74% and hypercapnia (PCO2 greater than 45 mm Hg) in 74% of all cases. After 24 hours, calibration shifts were less than 4 mm Hg in 90% of the measuring periods. In 86% of the infants, no skin changes were observed; in 12% of infants, there were transitional skin erythemas and in 2% a blister which disappeared without scarring. In newborn infants with normal BPs, continuous tcPCO2 monitoring at 42 degrees C can be extended for as many as 24 hours without loss of reliability or increased risk for skin burns.

Pacing redistributes glycogen within the developing myocardium.

Electrical pacing at physiological rate induces myocardial remodeling associated with regional changes in workload, blood flow and oxygen consumption. However, to what extent energy-producing pathways are also modified within the paced heart remains to be investigated. Pacing could particularly affect glycogen metabolism since hypertrophy stimulates glycolysis and increased workload favors glucose over fat oxidation. In order to test this hypothesis, we used the embryonic chick heart model in which ventricular pacing rapidly resulted in thinning of the ventricle wall and thickening of the atrial wall. Hearts of stage 22HH chick embryos were submitted in ovo to asynchronous and intermittent ventricular pacing delivered at physiological rate during 24 h. The resulting alterations of glycogen content were determined in atrium, ventricle and conotruncus of paced and sham-operated hearts. Hemodynamic parameters of the paced and spontaneously beating hearts were derived from computerized image analysis of video recordings. With respect to sham, paced hearts showed a significant decrease in glycogen content (nmoles glucose units/microg protein; mean+/-S.D.) only in atrium (1.48+/-0.40 v 0.84+/-0.34, n=8) and conotruncus (0.75+/-0.28 v 0.42+/-0.23, n=8). Pacing decreased the end diastolic and stroke volumes by 34 and 44%, respectively. Thus, the rapid glycogen depletion in regions remote from the stimulation site appears to be associated with regional changes in workload and remodeling. These findings underscore the importance of the coupling mechanisms between metabolic pathways and myocardial remodeling in the ectopically paced heart.

Suicide after successful deep brain stimulation for movement disorders.

The authors observed a high rate of suicide (6/140 patients, 4.3%) in a large cohort of patients with movement disorders treated with deep brain stimulation (DBS). Apparent risk factors included a previous history of severe depression and multiple successive DBS surgeries, whereas there was no relationship with the underlying condition, DBS target, electrical parameters, or modifications of treatment. Paradoxically, all patients experienced an excellent motor outcome following the procedure. The authors propose that patients at high risk for suicide should be excluded from DBS surgery.

Die epidurale Rückenmarkstimulation (SCS) zur Therapie peripherer arterieller Durchblutungsstörungen [Spinal cord stimulation (SCS) in the treatment of peripheral arterial occlusive disease]

Spinal cord stimulation (SCS) represents a well established procedure in the treatment of critical ischemia of the extremities. The knowledge and distribution of SCS in Austria are still poor despite satisfactory data. The evaluations and recommendations from the consensus group demonstrate that SCS might represent a suitable additional treatment option for selected patients with peripheral arterial disease (PAD) when performed in experienced centers under clear indications. The complication rate is low and mainly due to device-related problems. There are valid scientific criteria proving that SCS treatment can reduce the risk of amputation, decrease pain and improve wound healing in patients with non-reconstructable, non-unstable PAD in stages IV and V according to Rutherford (stages III and IV according to Fontaine).This effect is more evident when patient selection is based on tcPO(2) measurements. A careful selection of patients is essential for the success of this neuromodulatory treatment, in addition a certain degree of patient compliance in terms of perception and understanding of the therapy is mandatory.

Stimulation of ENaC activity by rosiglitazone is PPARγ-dependent and correlates with SGK1 expression increase.

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor gamma (PPARγ) agonists used to treat type 2 diabetes. TZD treatment induces side effects such as peripheral fluid retention, often leading to discontinuation of therapy. Previous studies have shown that PPARγ activation by TZD enhances the expression or function of the epithelial sodium channel (ENaC) through different mechanisms. However, the effect of TZDs on ENaC activity is not clearly understood. Here, we show that treating Xenopus laevis oocytes expressing ENaC and PPARγ with the TZD rosiglitazone (RGZ) produced a twofold increase of amiloride-sensitive sodium current (Iam), as measured by two-electrode voltage clamp. RGZ-induced ENaC activation was PPARγ-dependent since the PPARγ antagonist GW9662 blocked the activation. The RGZ-induced Iam increase was not mediated through direct serum- and glucocorticoid-regulated kinase (SGK1)-dependent phosphorylation of serine residue 594 on the human ENaC α-subunit but by the diminution of ENaC ubiquitination through the SGK1/Nedd4-2 pathway. In accordance, RGZ increased the activity of ENaC by enhancing its cell surface expression, most probably indirectly mediated through the increase of SGK1 expression.

Pharmacological stimulation of edar signaling in the adult enhances sebaceous gland size and function.

Impaired ectodysplasin A (EDA) receptor (EDAR) signaling affects ectodermally derived structures including teeth, hair follicles, and cutaneous glands. The X-linked hypohidrotic ectodermal dysplasia (XLHED), resulting from EDA deficiency, can be rescued with lifelong benefits in animal models by stimulation of ectodermal appendage development with EDAR agonists. Treatments initiated later in the developmental period restore progressively fewer of the affected structures. It is unknown whether EDAR stimulation in adults with XLHED might have beneficial effects. In adult Eda mutant mice treated for several weeks with agonist anti-EDAR antibodies, we find that sebaceous gland size and function can be restored to wild-type levels. This effect is maintained upon chronic treatment but reverses slowly upon cessation of treatment. Sebaceous glands in all skin regions respond to treatment, although to varying degrees, and this is accompanied in both Eda mutant and wild-type mice by sebum secretion to levels higher than those observed in untreated controls. Edar is expressed at the periphery of the glands, suggesting a direct homeostatic effect of Edar stimulation on the sebaceous gland. Sebaceous gland size and sebum production may serve as biomarkers for EDAR stimulation, and EDAR agonists may improve skin dryness and eczema frequently observed in XLHED.

Effects of amygdala-hippocampal stimulation on interictal epileptic discharges.

Deep brain stimulation (DBS) of different nuclei is being evaluated as a treatment for epilepsy. While encouraging results have been reported, the effects of changes in stimulation parameters have been poorly studied. Here the effects of changes of pulse waveform in high frequency DBS (130Hz) of the amygdala-hippocampal complex (AH) are presented. These effects were studied on interictal epileptic discharge rates (IEDRs). AH-DBS was implemented with biphasic versus pseudo monophasic charge balanced pulses, in two groups of patients: six with temporal lobe epilepsy (TLE) associated with hippocampal sclerosis (HS) and six with non lesional (NLES) temporal epilepsy. In patients with HS, IEDRs were significantly reduced with AH-DBS applied with biphasic pulses in comparison with monophasic pulse. IEDRs were significantly reduced in only two patients with NLES independently to stimulus waveform. Comparison to long-term seizure outcome suggests that IEDRs could be used as a neurophysiological marker of chronic AH-DBS and they suggest that the waveform of the electrical stimuli can play a major role in DBS. We concluded that biphasic stimuli are more efficient than pseudo monophasic pulses in AH-DBS in patients with HS. In patients with NLES epilepsy, other parameters relevant for efficacy of DBS remain to be determined.

BAFF production by antigen-presenting cells provides T cell co-stimulation.

The B cell-activating factor from the tumor necrosis factor family (BAFF) is an important regulator of B cell immunity. Recently, we demonstrated that recombinant BAFF also provides a co-stimulatory signal to T cells. Here, we studied expression of BAFF in peripheral blood leukocytes and correlated this expression with BAFF T cell co-stimulatory function. BAFF is produced by antigen-presenting cells (APC). Blood dendritic cells (DC) as well as DC differentiated in vitro from monocytes or CD34+ stem cells express BAFF mRNA. Exposure to bacterial products further up-regulates BAFF production in these cells. A low level of BAFF transcription, up-regulated upon TCR stimulation, was also detected in T cells. Functionally, blockade of endogenous BAFF produced by APC and, to a lesser extent, by T cells inhibits T cell activation. Altogether, this indicates that BAFF may regulate T cell immunity during APC-T cell interactions and as an autocrine factor once T cells have detached from the APC.

Auditory-visual multisensory interactions in humans: timing, topography, directionality, and sources.

Current models of brain organization include multisensory interactions at early processing stages and within low-level, including primary, cortices. Embracing this model with regard to auditory-visual (AV) interactions in humans remains problematic. Controversy surrounds the application of an additive model to the analysis of event-related potentials (ERPs), and conventional ERP analysis methods have yielded discordant latencies of effects and permitted limited neurophysiologic interpretability. While hemodynamic imaging and transcranial magnetic stimulation studies provide general support for the above model, the precise timing, superadditive/subadditive directionality, topographic stability, and sources remain unresolved. We recorded ERPs in humans to attended, but task-irrelevant stimuli that did not require an overt motor response, thereby circumventing paradigmatic caveats. We applied novel ERP signal analysis methods to provide details concerning the likely bases of AV interactions. First, nonlinear interactions occur at 60-95 ms after stimulus and are the consequence of topographic, rather than pure strength, modulations in the ERP. AV stimuli engage distinct configurations of intracranial generators, rather than simply modulating the amplitude of unisensory responses. Second, source estimations (and statistical analyses thereof) identified primary visual, primary auditory, and posterior superior temporal regions as mediating these effects. Finally, scalar values of current densities in all of these regions exhibited functionally coupled, subadditive nonlinear effects, a pattern increasingly consistent with the mounting evidence in nonhuman primates. In these ways, we demonstrate how neurophysiologic bases of multisensory interactions can be noninvasively identified in humans, allowing for a synthesis across imaging methods on the one hand and species on the other.