Effect of Propafenone on the Contractile Activity of Latissimus Dorsi Muscle Isolated in an Organ Chamber: Experimental Study in Rats

OBJECTIVE: To study the effect of propafenone on the contractile function of latissimus dorsi muscle isolated from rats in an organ chamber. METHODS: We studied 20 latissimus dorsi muscles of Wistar rats and divided them into 2 groups: group I (n=10), or control group - we studied the feasibility of muscle contractility; group II (n=10), in which the contralateral muscles were grouped - we analyzed the effect of propafenone on muscle contractility. After building a muscle ring, 8 periods of sequential 2-minute baths were performed, with intervals of preprogrammed electrical stimulation using a pacemaker of 50 stimuli/min. In group II, propafenone, at the concentration of 9.8 µg/mL, was added to the bath in period 2 and withdrawn in period 4. RESULTS: In group I, no significant depression in muscle contraction occurred up to period 5 (p>0.05). In group II, a significant depression occurred in all periods, except between the last 2 periods (p<0.05). Comparing groups I and II only in period 1, which was a standard period for both groups, we found no significant difference (p>0.05). CONCLUSION: Propafenone had a depressing effect on the contractile function of latissimus dorsi muscle isolated from rats and studied in an organ chamber.

Initial Energy for External Electrical Cardioversion of Atrial Fibrillation

OBJECTIVE - To investigate the initial energy level required for electrical cardioversion of atrial fibrillation (AF). METHODS - We studied patients undergoing electrical cardioversion in the 1st Multicenter Trial of SOCESP. Patients were divided into 2 groups according to the initial energy level of electrical cardioversion: 100J and > or = 150J. We compared the efficacy of the initial and final shock of the procedure, the number of shocks administered, and the cumulative energy levels. RESULTS - Eight-six patients underwent electrical cardioversion. In 53 patients (62%), cardioversion was started with 100J, and in 33 patients (38%), cardioversion was started with > or = 150J. Groups did not differ regarding clinical features and therapeutical interventions. A tendency existed towards greater efficacy of the initial shock in patients who received > or = 150J (61% vs. 42% in the 100J group, p=0.08). The number of shocks was smaller in the > or = 150J group (1.5±0.7 vs. 2.1±1.3, p=0.04). No difference existed regarding the final efficacy of electrical cardioversion and total cumulative energy levels in both groups. In the subgroup of patients with recent-onset AF (<=48h), the cumulative energy level was lower in the 100J group (240±227J vs. 324±225J, p=0.03). CONCLUSION - Patients who were given initial energy of > or = 150J received fewer counter shocks with a tendency toward greater success than those patients who were given 100J; however, in patients with recent-onset AF, the average cumulative energy level was lower in the 100J group. These data suggest that electrical cardioversion should be initiated with energy levels > or = 150J in patients with chronic AF.

Connection of Lightning Activity with Air Electrical Conductivity in Dusheti

Some results of investigations of the connection of the parameters of thunderstorm activity with the air electrical conductivity are represented.

Nichtlineare Wechselwirkung im auditorischen Kortex nach Stimulation mit Sequenzen mehrerer Sinustöne

Monkey, neuron, auditory cortex, temporal processing, nonlinear interaction, sequence, temporal coding

Instability of excitation waves induced by electrical fields

Pyrogallol, uncatalyzed bromate oscillator, electric field, pulse wave, Belousov-Zhabotinsky reaction, reversal

Neural dynamics and their relationship to learning behavior in response tot stimulation with a cortical neuroprosthesis

Sensory cortex, neuroprosthetics, brain-machine-interfaces, neurodynamics, learning, perception, embodied cognition

Neural Mechanisms and Delayed Gastric Emptying of Liquid Induced Through Acute Myocardial Infarction in Rats

Background: In pathological situations, such as acute myocardial infarction, disorders of motility of the proximal gut can trigger symptoms like nausea and vomiting. Acute myocardial infarction delays gastric emptying (GE) of liquid in rats. Objective: Investigate the involvement of the vagus nerve, α 1-adrenoceptors, central nervous system GABAB receptors and also participation of paraventricular nucleus (PVN) of the hypothalamus in GE and gastric compliance (GC) in infarcted rats. Methods: Wistar rats, N = 8-15 in each group, were divided as INF group and sham (SH) group and subdivided. The infarction was performed through ligation of the left anterior descending coronary artery. GC was estimated with pressure-volume curves. Vagotomy was performed by sectioning the dorsal and ventral branches. To verify the action of GABAB receptors, baclofen was injected via icv (intracerebroventricular). Intravenous prazosin was used to produce chemical sympathectomy. The lesion in the PVN of the hypothalamus was performed using a 1mA/10s electrical current and GE was determined by measuring the percentage of gastric retention (% GR) of a saline meal. Results: No significant differences were observed regarding GC between groups; vagotomy significantly reduced % GR in INF group; icv treatment with baclofen significantly reduced %GR. GABAB receptors were not conclusively involved in delaying GE; intravenous treatment with prazosin significantly reduced GR% in INF group. PVN lesion abolished the effect of myocardial infarction on GE. Conclusion: Gastric emptying of liquids induced through acute myocardial infarction in rats showed the involvement of the vagus nerve, alpha1- adrenergic receptors and PVN.

Elektrische Anregung von Zellsystemen mittels einer zweidimensionalen Elektrodenstruktur

Electrical stimulation, neuron, yeast, excitation mechanism, planar electrode structure

Beeinflussung von auditorischer Objektbildung durch visuelle Stimulation

Streaming, Auditory Scene Analysis, Mismatch Negativity, Auditorische Szenenanalyse, Stream-Segregation

Influence of nucleus accumbens core or shell stimulation on early long-term potentiation in the dentate gyrus of freely moving rats

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2010

Dynamik einiger Neurotransmitter beim räumlichen Lernen und nach elektrischer Stimulation im Hippocampus und Cortex praefrontalis der Ratte

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2010

Surface electrical charge of bloodstream trypomastigotes of Trypanosoma cruzi strains

Bloodstream trypomastigotes of some Trypanosoma cruzi strains were processed through DEAE-cellulose columns under standardized conditions. The results obtained suggest mainly that these strains present different surface charges, that there are subpopulations of bloodstream trypomastigotes as regards electrical charges and that the broad forms are less negative than the slender ones.

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.

Cells with neuronal characteristics differentiate and persist for one year in rat optic nerve explants cultures.

Evidence concerning the presence or absence of common neuronglia lineages in the postnatal mammalian central nervous system is still a matter of speculation. We address this problem using optic nerve explants, which show an extremely long survival in culture. Morphological, immunocytochemical and immunochemical methods were applied. The results obtained from in vitro tissue were compared with optic nerves (ONs) and whole-brain samples from animals of different ages. Newborn rat ONs represented the starting material of our tissue culture; they are composed of unmyelinated axons, astrocytes and progenitor cells but devoid of neuronal cell bodies. At this age, Western blots of ONs were positively stained by neurofilament and synapsin I specific antibodies. These bands increased in intensity during postnatal in situ development. In explant cultures, the glia cells reach a stage of functional differentiation and they maintain, together with undifferentiated cells, a complex histotypic organization. After 6 days in vitro, neurofilaments and synapsin I could not be detected on immunoblots, indicating that 1) axonal degeneration was completed, and 2) neuronal somata were absent at the time. Surprisingly, after about 4-5 weeks in culture, a new cell type appeared, which showed characteristics typical of neurons. After 406 days in vitro, neurofilaments and synapsin I were unequivocally detectable on Western blots. Furthermore, both immunocytochemical staining and light and electron microscopic examinations corroborated the presence of this earlier-observed cell type. These in vitro results clearly show the high developmental plasticity of ON progenitor cells, even late in development. The existence of a common neuron-glia precursor, which never gives rise to neurons in situ, is suggested.