Indications à la stimulation cardiaque dans la syncope vasovagale [Pacing in vasovagal syncope].

This article presents a critical review of the literature about the potential benefit of cardiac pacing in patients suffering from vasovagal or neurocardiogenic syncope. The manifestation of vasovagal syncope comprises some reflex bradycardia and vasoplegia resulting in cerebral hypoperfusion that ultimately leads to a loss of consciousness. The literature reports conflicting results of the potential benefit of cardiac pacing on the prevention of recurrence of vasovagal events. A detailed analysis of the inclusion criteria of these studies permits to clarify the discrepancy. Only patients older than 50 years with prolonged sinus pause at time of syncope benefit of the implantation of a cardiac pacemaker.

Direct angiotensin type 2 receptor (AT2R) stimulation attenuates T-cell and microglia activation and prevents demyelination in experimental autoimmune encephalomyelitis in mice.

In the present study, we evaluated stimulation of the angiotensin type 2 receptor (AT2R) by the selective non-peptide agonist Compound 21 (C21) as a novel therapeutic concept for the treatment of multiple sclerosis using the model of experimental autoimmune encephalomyelitis (EAE) in mice. C57BL-6 mice were immunized with myelin-oligodendrocyte peptide and treated for 4 weeks with C21 (0.3 mg/kg/day i.p.). Potential effects on myelination, microglia and T-cell composition were estimated by immunostaining and FACS analyses of lumbar spinal cords. The in vivo study was complemented by experiments in aggregating brain cell cultures and microglia in vitro. In the EAE model, treatment with C21 ameliorated microglia activation and decreased the number of total T-cells and CD4+ T-cells in the spinal cord. Fluorescent myelin staining of spinal cords further revealed a significant reduction in EAE-induced demyelinated areas in lumbar spinal cord tissue after AT2R stimulation. C21-treated mice had a significantly better neurological score than vehicle-treated controls. In aggregating brain cell cultures challenged with lipopolysaccharide (LPS) plus interferon-γ (IFNγ), AT2R stimulation prevented demyelination, accelerated re-myelination and reduced the number of microglia. Cytokine synthesis and nitric oxide production by microglia in vitro were significantly reduced after C21 treatment. These results suggest that AT2R stimulation protects the myelin sheaths in autoimmune central nervous system inflammation by inhibiting the T-cell response and microglia activation. Our findings identify the AT2R as a potential new pharmacological target for demyelinating diseases such as multiple sclerosis.

The role of the right parietal cortex in sound localization: a chronometric single pulse transcranial magnetic stimulation study.

Auditory spatial functions, including the ability to discriminate between the positions of nearby sound sources, are subserved by a large temporo-parieto-frontal network. With the aim of determining whether and when the parietal contribution is critical for auditory spatial discrimination, we applied single pulse transcranial magnetic stimulation on the right parietal cortex 20, 80, 90 and 150 ms post-stimulus onset while participants completed a two-alternative forced choice auditory spatial discrimination task in the left or right hemispace. Our results reveal that transient TMS disruption of right parietal activity impairs spatial discrimination when applied at 20 ms post-stimulus onset for sounds presented in the left (controlateral) hemispace and at 80 ms for sounds presented in the right hemispace. We interpret our finding in terms of a critical role for controlateral temporo-parietal cortices over initial stages of the building-up of auditory spatial representation and for a right hemispheric specialization in integrating the whole auditory space over subsequent, higher-order processing stages.

Transient stimulation of glucose metabolism by insulin in the 1-day chick embryo.

Effects of insulin upon glucose metabolism were investigated in chick embryos explanted in vitro during the first 30 h of incubation. Insulin stimulated the glucose consumption of the chick gastrula (18 h) and neurula (24 h), but had no effect on the late blastula (0 h:laying) and on the stage of six to eight somites (30 h). The increase in glucose consumption concerned both the embryonic area pellucida (AP) and extraembryonic area opaca (AO). AP responded to a greater extent (50%) and at a lower range of concentrations (0.1-1.0 ng/ml) than AO (30%; 1-100 ng/ml). Insulin had no effect on the oxygen consumption of blastoderms, whereas it stimulated the aerobic lactate production (approximately 70% of the additional glucose consumption was converted to lactate). The nanomolar range of stimulating concentrations suggests that insulin has a specific effect in the chick embryo, and that it could modulate glucose metabolism in ovo as well. The transient sensitivity of the embryo to insulin is discussed in relation to behavior of mesodermal cells.

Controlled study of 50-Hz repetitive transcranial magnetic stimulation for the treatment of Parkinson disease.

OBJECTIVE: To investigate the safety and efficacy of 50-Hz repetitive transcranial magnetic stimulation (rTMS) in the treatment of motor symptoms in Parkinson disease (PD). BACKGROUND: Progression of PD is characterized by the emergence of motor deficits that gradually respond less to dopaminergic therapy. rTMS has shown promising results in improving gait, a major cause of disability, and may provide a therapeutic alternative. Prior controlled studies suggest that an increase in stimulation frequency might enhance therapeutic efficacy. METHODS: In this randomized, double blind, sham-controlled study, the authors investigated the safety and efficacy of 50-Hz rTMS of the motor cortices in 8 sessions over 2 weeks. Assessment of safety and clinical efficacy over a 1-month period included timed tests of gait and bradykinesia, Unified Parkinson's Disease Rating Scale (UPDRS), and additional clinical, neurophysiological, and neuropsychological parameters. In addition, the safety of 50-Hz rTMS was tested with electromyography-electroencephalogram (EMG-EEG) monitoring during and after stimulation. RESULTS: The authors investigated 26 patients with mild to moderate PD: 13 received 50-Hz rTMS and 13 sham stimulation. The 50-Hz rTMS did not improve gait, bradykinesia, and global and motor UPDRS, but there appeared a short-lived "on"-state improvement in activities of daily living (UPDRS II). The 50-Hz rTMS lengthened the cortical silent period, but other neurophysiological and neuropsychological measures remained unchanged. EMG/EEG recorded no pathological increase of cortical excitability or epileptic activity. There were no adverse effects. CONCLUSION: It appears that 50-Hz rTMS of the motor cortices is safe, but it fails to improve motor performance and functional status in PD. Prolonged stimulation or other techniques with rTMS might be more efficacious but need to be established in future research.