The effect of dexphenmetrazine and acetyldexphenmetrazine upon epileptic electrographic activities in the brain of the turtle.

The effect of acetyldexphenmetrazine (ADP) and dexphenmetrazine (DP) on normal and epileptic electrographic activities in the cortical and thalamic structures of the turtle brain were studied in curarized and artificially ventilated animals. Both drugs almost exclusively influenced cortical activities. The effect of low doses of ADP and DP was similar--they desynchronized cortical activity and suppressed the activity of a cortical penicillin focus. They also elevated the cortical response to optic stimuli. Higher doses of ADP continued to suppress both normal and epileptic cortical activities. Higher doses of DP had a two phase effect with enhancement of epileptic activity in the first phase. Continuous trains of theta activity appeared after low doses of ADP and very often after both low and high doses of DP. The findings are discussed in terms of comparative physiology of the brain.     

Activation of epileptic electrographic phenomena in the human EEG by nasal air flow.

The activating effect of deep oral breathing (with the nose closed) and nasal hyperventilation (with mouth closed) was examined in 62 patients with three different kinds of epileptic EEG abnormalities: unilateral localized temporal (fronto-temporal, occipito-temporal) abnormalities - group F, bilateral episodic theta-delta abnormalities - group TH, and bilaterally synchronous spike and wave abnormalities - group SW. Nasal hyperventilation was much more effective in group F and TH. Its effect was already significant 30-60 seconds after the start of deep breathing. In the group SW there were no statistically significant differences between the effects of nasal and oral hyperventilation. Unilateral nasal hyperventilation (the other nasal cavity being closed by tamponade) demonstrated a more pronounced activating effect on ipsilateral localized temporal EEG abnormalities. These effects of deep nasal breathing can hardly be explained by metabolic-vascular mechanisms, which probably are involved in the course of oral hyperventilation. On the other hand they are in agreement with animal experiments demonstrating that the mechanical stimulus of nasal air flow operates as a synchronizing impulse for certain rhinencephalic structures.     

Activating effect of nasal air flow on epileptic electrographic abnormalities in the human EEG. Evidence for the reflect origin of the phenomenon

Deep nasal breathing [with the mouth closed] activates [to a certain extent selectively], in the human EEG, epileptic abnormalities of diencephalotemporal origin [Servít et al. 1977]. This activating effect could be suppressed by local anaesthesia of the mucosa membrane in the superior nasal meatus. The same abnormalities could be elicited or activated by air insufflation into the upper nasal cavity, without pulmonary hyperventilation. These results speak in favour of the assumption that a neural [reflex] mechanism of the activating effect of nasal hyperventilation is involved, with a reflexogenic area in the superior nasal meatus.     

Thalamocortical relations in the brain of the frog, Their role in the genesis of epileptic electrographic phenomena.

The existence of a thalamocortical reverberating circuit between the dorsal thalamic and primordial hippocampal structures could be proved in the brain of the frog (Rana temporarial) by evoking recruiting potentials. Unlike the turtle, this circuit does not take part in the genesis of electrographic phenomena in the corticogram of the frog under normal resting conditions. Spindle activity could not be observed in the EEG of curarized frogs. On the other hand, thalamic structures can influence paroxysmal susceptibility of the frog forebrain. The generation of the penicillin focus could be accelerated and paroxysmal electrographic activities elicited by iontophoretic application of penicillin into dorsal thalamic structures and/or rhythmic electric stimulation of this region. The features of thalamocortical cooperation in the frog and in the turtle have been compared.     

Alternative leech vectors for frog and turtle trypanosomes.

Trypanosoma pipientis infections were achieved by exposing laboratory-raised bullfrog tadpoles (Rana catesbeiana) to the leech Desserobdella picta that had fed on infected frogs. Likewise, a laboratory-raised snapping turtle (Chelydra serpentina) was infected with Trypanosoma chrysemydis following exposure to infected Placobdella ornata. Transmission of the trypanosomes by these leeches constitutes new vector records for the parasites. The biology of D. picta and P. ornata suggests that they are more important in transmitting these flagellates than the species of leech previously reported as vectors.     

Influence of lithium upon the intracellular potential of frog skin epithelium.

The effect of Li upon the intracellular potential of frog skin (Rana esculenta) was investigated. In the range between 1 and 25 mM Li in the epithelial bathing solution, a semilogarithmic linear relationship between [Li] and intracellular potential under short circuit conditions was obtained. The intracellular potential at all [Li] is quantitatively sufficient to explain the previously reported accumulation of Li in the intracellular space of the frog skin epithelium (Leblanc, G. 1972. Pfluegers Arch. 337:1) on the basis of a passibe entrance step at the outer border. A reduction of the intracellular potential by Li is also observed in the presence of 6 mM Na in the epithelial bathing solution. Consequences regarding the mechanism of uptake of Na across the outer border of the frog skin are discussed.     

Comparative study of nonlinear properties of EEG signals of normal persons and epileptic patients

Background  

Investigation of the functioning of the brain in living systems has been a major effort amongst scientists and medical practitioners. Amongst the various disorder of the brain, epilepsy has drawn the most attention because this disorder can affect the quality of life of a person. In this paper we have reinvestigated the EEGs for normal and epileptic patients using surrogate analysis, probability distribution function and Hurst exponent.     

Influence of lithium upon the intracellular potential of frog skin epithelium

Summary The effect of Li upon the intracellular potential of frog skin (Rana esculenta) was investigated. In the range between 1 and 25mm Li in the epithelial bathing solution, a semilogarithmic linear relationship between [Li] and intracellular potential under short circuit conditions was obtained. The intracellular potential at all [Li] is quantitatively sufficient to explain the previously reported accumulation of Li in the intracellular space of the frog skin epithelium (Leblanc, G. 1972.Pfluegers Arch. 337:1) on the basis of a passive entrance step at the outer border. A reduction of the intracellular potential by Li is also observed in the presence of 6mm Na in the epithelial bathing solution. Consequences regarding the mechanism of uptake of Na across the outer border of the frog skin are discussed.     

Influence of serosal Cl on transport properties and cation activities in frog skin

Summary Treatment of resident peritoneal macrophages of rats with small unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC SUV) potentiated their activation for tumor cell lysis by endotoxins. The fluorescence polarization of diphenylhexatriene (DPH) embedded in rough endoplasmic reticulum membranes isolated from DPPC SUV-treated macrophages was enhanced. The average fluorescence lifetime of DPH and the rotational correlation time deduced from anisotropy decay were unchanged, whereas the residual anisotropy and hence the order parameter were increased. The measurement of the fluorescence anisotropy of DPH as a function of the temperature showed a phase transition. No phase transition was observed in the rough endoplasmic reticulum membranes of macrophages either treated or not treated with cholesterol/DPPC SUV (1/1; mol/mol). The synergistic effect of DPPC SUV on the tumoricidal activity of macrophages induced by endotoxins appears to be correlated with the changes in the properties of the rough endoplasmic reticulum membranes. Both effects were transient; they had the same kinetics of induction and reversion, and they were both inhibited by cholesterol.     

Influence of short-term hypothermia upon the normal or ischaemic dog kidney.

Dog kidneys were subjected to 1 hr of normothermic ischaemia, maintained for 3 hr in hypothermia with autologous heparinised blood, or underwent a combination of these two treatments and were examined either immediately after the trauma or at different periods up to 1 week after autotransplantation. Clearance tests, tubular amino acid and sugar transport, cortical Na⁺K⁺-ATPase levels, acid phosphatase liberated into the renal circulation, and morphology were investigated. The results obtained (i) confirmed the severe, but slowly and progressively reversible lesion after ischaemia; (ii) revealed the functional impairment with almost normal morphology after hypothermia; and (iii) indicated the immediate and irreparable deterioration of renal function after ischaemic kidneys were subjected to short-term hypothermic treatment of this type.     

Influence of temperature and cyanide on electrical and mechanical activities of isoproterenol-damaged frog heart

The electrical and mechanical activities of myocardial strips from Rana pipiens treated with isoproterenol (ISO) were studied during cyanide hypoxia at different bath temperatures (12, 25 and 35 degrees C). In normal myocardium at 12 degrees C, the action potential duration (APD) was almost unchanged but the isometric force (P) was reduced to about 60% after 30 min in 3 mmol/l NaCN. At 25 degrees C, APD and P decreased to about 80 and 60%, respectively, after exposure to cyanide for 30 min. At 35 degrees C, a fast decrease of APD (to about 30%) and P (to about 10%) was seen within 30 min. In all cases, washout of cyanide interactions was possible. Large effects occurred when ISO-damaged myocardium was exposed to cyanide. During the initial 30 min of CN-treatment, APD and P were significantly reduced in the whole temperature range between 12 and 35 degrees C, when compared with controls. When the cyanide exposure times were long enough, all preparations developed contracture. Increase of the temperature and/or ISO-pretreatment shortened the time-course for resting tension increase. The effects of cyanide on APD and resting tension (RT) were strongly correlated and presumably a result of a cyanide-induced rise of the intracellular free calcium concentration (Ca2+i).