Assessment of the clinical utility of transcranial doppler in acute stroke patients

The aim of this work is to correlate clinical features of stroke progression with transcranial Doppler findings of arterial reperfusion, and to define the prevalence and time course of Doppler emboli signals after acute stroke Transcranial Doppler [TCD] as a non-invasive, simple, cheap, and repeatable gives on-line information about recanalisation of obstructed vessels. An increase in TCD velocity can be due to stenosis, vasospasm, or hyperemia. The microemboli signals are transient, unidirectional, 3 to 60 decibels in amplitude, and have a clicking sound. Their duration is inversely proportional to their velocity. They are randomly distributed within the cardiac cycle. The overall prevalence of microemboli in acute stroke patients depends on patient population, treatment regimens, study protocols, and prior stroke or TIA. One hundred and fifteen stroke patients [61 females and 54 males], with mean age 66.7+1-15.4, were valuated clinically on admission using National Institute of Health Stroke Scale [NIHSS], TCD study was done on admission and repeated for patients who stayed more than one day in the hospital. Patients were classified according to the perfusion patterns, CT appearance and risk factors of stroke. Eighty-eight patients [49 men and 39 women] with mean age 67.2 +/- 13.9 years were successfully monitored for microemboli signals [MES]. Clinically, 18[20%] patients were diagnosed as TIA and 70[80%] as complete stroke. There were 11 with atrial fibrillation [AF], 17 with myocardial infraction [MI] 14 with internal carotid artery stenosis [CS], and 46 patients with other risk factors such as hypertension, diabetes, cigarette smoking and alcohol consumption. The overall prevalence MES was 10.2% [12% in MI patients, 0% in AF patients, and 50% in CS patients]. Carotid stenosis patients had significantly [p=0.04] higher prevalence of embolic signals than the other groups. There was a significant difference [p=0.001] in the mean velocities [MV] between the four groups in the healthy hemisphere, but not in the diseased one. There was a significant difference [p=0.05] in healthy sides between AF and other risk factors group. Also there was a significant difference [p=0.01] in both healthy and diseased sides between CS and AF patients. There was a significant difference [p=0.01] between four groups in the pulsatility indices [P1] in the diseased sides but not in the healthy sides. Also positive correlation was obtained between perfusion pattern and NIHSS in each group of stroke subtype. It was higher in both lacuner infarcts and normal CT groups and lower in territorial group. The perfusion patterns evolved from hypoperfusion, normal perfusion, and then hypoperfusion side with time. A negative correlation was established between the time and asymmetry indices [Al], more significant [p=0.02] in hypoperfusion group. Conclusions: In conclusions TCD is a helpful method for studying the pathophysiological mechanisms in stroke. IT is recommended to early, prolonged monitoring, and strict setting of TCD machine. Cerebral embolism is the likely mechanism of stroke in MI patients, while haemodynamic insufficiency may be cerebral haemodynamic state. Perfusion patterns in the acute stage are indicators for the clinical condition and should be combined with CT results and clinical scoring

Instrumental set up for investigation of the hypothalamic thermoregulatory system

This work is a method for setting up a system by which the function of preoptic anterior hypothalamic [POAH] area can be well investigated. To do this, we have used a water perfused thermode to heat and cool the POAH area. A part of this thermode is implanted in the rabbit's hypothalamus, and the other part is attached to a plastic tubing piece. The diameter of this piece is so chosen as to allow a loose fitting inside the implanted tube. It also allows a loose fitting inside the tube forming a water - tight junction. The hypothalamus temperature could be manipulated by changing the temperature of water circulation through the thermode. Two thermostatically controlled water baths are also used to control the water temperature which enters the thermode. Heat can be transferred between the thermode and brain tissues across the thermode wall. The rate of water flow can be controlled by applying a positive or negative pressure by the help of a vacuum pump

Caloric effects of hypothalamus on rabbit's skin

The function of the thermoregulatory center of brain in regulating the process of heat exchange in rabbit's ear has been investigated in this work. Rabbits were stereotaxically implanted with water perfused thermodes in the brain to heat the hypothalamic thermoregulatory center. The normal hypothalamic temperature was found to be about 38.4 degree. This temperature maintains at that level despite the changes of the ambient temperatures due to a number of thermoregulatory mechanisms. One of these mechanisms is the role of ear pinna in varying the blood flow rate by constriction or dilation of the ear vessels. The work suggests that if the hypothalamic temperature is altered, a prominent response is achieved. The rise in ear temperature as a result of hypothalamus heatness seems to level off at higher temperatures. This may indicate a sort of saturation of the vasomotor system. This is a result of maximum dilation of blood vessels which maximizes the blood flow rate. This maximum dilation is found to be occurred at a hypothalamic temperature of 41-42 degree

Evoked potential of hippocampal structure by adequate stimulation

Neural behaviour of rabbits hippocampus was investigated using photic stimulation of frequency ranging from 150 to 1800 F/min. Electroencephalographic [[EEC]] activities of the hippocampal region [CA1] were analyzed by the help of a digital PDF - 11 computer. Enhancement factor, which is a measure of the arousal state of the animal, showed an increase with the stimulation frequency. Statistical parameters of the evoked potentials, such as average, standard deviation, full-wave rectified integral, and delay time were computed. The average potential value was found to be 339 p.V at a frequency of 800 F/min. The potential values decreased as the frequency increased, reaching minimum at 1800 F/min. The full-wave rectified integral, being a measure of the inhibition process of hippocampus, indicated a decrease after stimulation irrespective of the stimuli frequency. Delay time for the elicitation of theta-waves was observed to be 350 msec at stimulation frequency of 200 F/min. At higher frequencies such 1800 F/min, the delay time decreased to 210 msec. The frequency and the amplitude of theta-waves was calculated as functions of the stimulation frequency. The highest frequency of theta-waves was observed at 800 F/min

analogue modeling study of hippocampal theta rhythm in rabbits

Electroencephalographic [EEG] activity of the hippocampal region of rabbits was investigated before and after photic stimulation of frequencies ranging from 150 to 1800 flash/min [F/min]. A study of the changes of photic stimulation and the frequency of theta waves, the most dominated EEG signal, was conducted. Then a mathematical relationship was tailored for this study for proposing an analogue model. The work suggests an analogue model predicting the frequency values of the theta waves close to those measured experimentally over the studied range of photic stimuli frequencies. The r.m.s. error was found to be less than 4.75 percent. The difference between the experimental data and the suggested model is meaningful, since the model can not represent precisely the biological process, this is due to the undetermined behaviour of the nervous system. The found error could be reduced by adding more R.L.C. branches. The proposed model makes it possible to study the mechanism by which the visual system of rabbit behaves under the influence of photic stimulations

Serum procollagen type III-peptide in healthy normal subjects and its importance in hepatic patients

Blood samples were collected from healthy normal and hepatic subjects in order to estimate the level of serum procollagen type III- peptide [by RIA technique] as well as liver function tests. Hepatic patient samples were classified into two groups according to the stage of liver injury i.e. early and late phase. Our data revealed that there is a close relationship between the level of serum procollagen and the stage of liver disease. It could be used as a good marker for the differentiation between the two phases of hepatic injury which should helps the treatment of these patients

CT versus MR in epilepsy

One hundred twenty seizure patients with positive EEG were studied using CT and MR to determine the efficacy of each in detection of epileptic focus. MR was considered to be the imaging procedure of choice for detection of an epileptogenic focus in seizure patients. When indicated, CT may be done as a second procedure to distinguish neoplasms from thrombosed vascular malformations, or to detect small foci of calcification and other lesions

Brain electrical activity mapping in epilepsies

Brain electrical activity map [BEAM] of 508 cases of epilepsy [both generalized and partial] were studied to demonstrate and compare this method with that of routine EEG for quantification and localization of regions of epileptogenesis. There was a good correlation between BEAM and the EEG in [74%] of cases. The BEAM was less efficient in detecting generalized epilepsy, but it was much better regarding partial abnormalities, even when EEG was normal or nearly so. Overall brain electrical activity maps did appear to offer data which were useful and complimentary to other available test results. Considerable care needs to be taken to identify artifacts and normal EEG variant when interpreting these tests

Relation between cyclosporin circulated level in serum and hepato-renal toxicity in kidney-transplanted patients

Blood samples of kidney -transplanted patients were collected and divided into five groups according to their cyclosporin circulated level in serum [less than 50 up to more than 200 ng/ml].Biochemical parameters of hepato-renal function were carried out. Also, cyclosporin level in serum was determined using RIA method. Our results revealed that there is a close relationship between the circulated level of cyclosporin in serum and hepatorenal function. A signs of toxicity was observed in patients with cyclosprin level over 200 ng/ml