[Interhemisphere asymmetry of the CSF dynamics and biomechanical properties of the skull].

This investigation shows that both intracranial liquor circulation and skull biomechanical properties evaluated by its pliability (compliance) to intracranial pressure are characterised by marked interhemisphere asymmetry. The interhemisphere differences of cerebrospinal fluid mobility were evaluated by means of asymmetry coefficient (right/left ratio of liquor mobility) which was found to be 1.25-1.

[Biomechanical properties of the human cranium: aging aspects].

Biomechanical properties of the human skull affect its dynamic tensility (pliability, compliance) by changes of intracranial volume and pressure (deltaV/deltaP). The goal of this study is to substantiate a possibility of noninvasive and dynamic evaluation of cranial compliance. The transcranial dopplerogram of middle cerebral artery and hemispheric bioimpedance were synchronously recorded, which represent information about pulsative changes of intracranial pressure and volume, respectively.

[Slow-wave fluctuations in craniosacral space: hemo-liquorodynamic conception of origin].

In the paper, the mechanism of forming of rhythmic slow-wave fluctuations in craniospinal cavity was investigated. In five young healthy persons, at rest and under voluntary respiration arrest test, the bioimpedansograms of head and lumbosacral part of vertebral column were synchronously registered as these recordings reflect the changes of relationships between blood/CSF volumes in cranial and lumbosacral regions, respectively. The recordings were subjected to frequency and spectral computer analysis (PC Macintosh G-4, Chart 5.

[Age-related characteristics of relationships between brain blood flow, liquor dynamics and biomechanical properties of human cranium].

The peculiarities of relationships between changes of cerebral blood flow, intracranial liquor dynamics and skull biomechanics in humans were studied in an age aspect. For this aim, a non-invasive method was proposed based on concomitant registration of rheoencephalogram and transcranial dopplerogram and evaluation of relationships between intracranial volume and pulse pressure changes (P-V index). The data obtained were analyzed by pattern-phase computer processing and compared with the blood flow parameters.

[Dynamics of local cerebral blood flow in different somatosensory cortical layers during whisker stimulation in rats].

Whisker stimulation in rats was found to increase the local cerebral blood flow (lCBF), its SD and to damp slow oscillations. It was established that lCBF drops slightly within a few seconds after the stimulus onset. The data obtained suggest that lCBF evoked sensory stimulation changes are distinctly localized in different layers of the somatosensory cortex.

[The role of the CSF dynamic component in forming the periodic fluctuations in the electric impedance of the head].

In patients with partial craniospinal blocks, the impedance responses to certain functional tests were by 20-30% less obvious. Osteopathic procedures normalised the impedance fluctuations. The data obtained suggest that the CSF dynamics plays an important role in genesis and changes of the head impedance.

[Cerebral blood flow and cerebrovascular reactivity in the early postnatal ontogeny of rats].

The development of cortical cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) were studied in Wistar rats during early postnatal ontogenesis, in groups aged 2-5, 6-8, 9-11, 12-15, 16-18 and 19-25 days. CBF was measured polarographically using inhaled hydrogen clearance method, with platinum electrodes inserted into parietal cortex. At the mentioned age periods, CBF and its percentage of adult level averaged as 38 (21%), 81 (45%), 142 (78%), 85 (47%), 110 (61%), and 118 (65%) ml/100 g/min, respectively.

LCBF changes in rat somatosensory cortex during whisker stimulation monitored by dynamic H2 clearance.

We evaluated increases in local cerebral blood flow (LCBF) localized to single activated cortical columns by H2 clearance methods. The rat whisker-barrel cortex is a model for cortical function and neural processing in active explorative behaviors. Up to four 30-40 microns Pt wire electrodes were inserted in or near the rat whisker-barrel cortex.

[A comparison of the measurements of local cerebral blood flow by hydrogen clearance with hydrogen inhalation and by its electrochemical generation in brain tissue].

The goal of the present investigation was to compare data received by modifications of H2-clearance method with inhalation (H2-Inh) and electrochemical generation in brain tissue (H2-Gen) of H2 from the same recording electrodes in acute experiments (urethane 1g/kgip) with Wistar rats (n = 39). Block of three or four Pt electrochemically sharpened electrodes to tip diameters of 20-40 mu, 0.3-0.

[Combinations of methods for the monitoring of the cerebral microcirculation].

Any single method for measuring changes in local cerebral blood flow (LCBF) or blood vessels during physiological stimuli has individual strengths and deficiencies. The coupling of multiple methods based on different physical principles permits simultaneous measurements and tests of interrelated cerebrovascular changes and mechanisms. The present paper describes combined recordings of LCBF by H2 clearance with inhalation (H2Cl-Inh) and with steady electrochemical generation (H2Cl-Gen), by laser Doppler flowmetry (LDF) and by dimensional changes in surface vessels with videomicroscopy through acute cranial windows in rats anesthetized with urethane 1g/kg or urethane (0.

[The characteristics of the correlation of the functional activity, blood supply and structural organization in the sensory-deprived cerebral cortex in rats].

The feature of correlation between functional activity of the brain tissue and structural-functional characteristics of the vascular system after sensory deprivation by the removal of whiskers in newborn animals were studied in nembutal-anaesthetized rats in comparison to the animals under d-tubocurarine with local anesthesia. It has been shown that there are major changes of EP parameters and ECoG in the sensory-deprived brain area and diminution of brain cortex thickness. Changes in the vascular system are mainly structural, what are revealed as disorganization in angioarchitecture of radial arteries.

[Relation of the level of blood flow and reactivity of cerebral vessels to the functional state of brain tissue].

The local cerebral blood flow (LCBF) and cerebrovascular reactivity to CO2 inhalation test were studied in rabbits after experimental local brain lesions. A decrease of the LCBF and cerebrovascular reactivity was observed in the grey and white matter surrounding the traumatic focus at the distance of about 15 mm, being minimal on the 3rd-5th days followed by normalizing by the 10th-14th days after lesions. The cerebrovascular reactivity was found to be a valuable prognostic parameter to assess the functional restoration of the brain.

[Measurement of total cerebral blood flow in man by means of the hydrogen clearance method].

The authors discuss a new method for measuring the overall cerebral blood flow in man from analysis of the hydrogen clearance curves recorded in the internal jugular vein with a sounding platinum electrode. The hydrogen clearance curves are polyexponential in character and for calculating the blood flow it is therefore necessary to use the stochastic method. The use of the "initial inclination" method is also admissible in proximate curve analysis.

[Relationship between the intracranial pressure, intracranial blood volume and total cerebral blood flow].

Studies in cats and in neurosurgical patients reveal that intraskull pressure, blood volume and total brain blood flow depend on the same factors, to a different extent though. This is determined by structural--functional organization of the intraskull circulation system, the analysis of which revealed a scheme of functional interrelationships among volumes and pressures of fluid media in the closed skull space. The features of interrelationships are not rigid and can have their own specifics in concrete situations.

[Informativeness of indices of reactions of cerebral vessels to adequate stimuli].

The functional stability of cerebral circulation involves its ability to resist against external influences and is based on the cerebral vessels reactivity. Objective methods for evaluation of this reactivity are proposed using standard and specific functional loads. The indices of intracranial and systemic hemodynamics were recorded in experimental animals, healthy humans and patients with head injuries during postoperative period.