Analysis of the rat brain surface temperature and cerebrocortical microflow changes

Celem badań było sprawdzenie czy zmiany temperatury powierzchni mózgu szczura rejestrowane za pomocą kamery termowizyjnej korelują ze zmianami mózgowego przepływu krwi. Przepływ krwi mierzono w korze mózgowej za pomocą sondy laser-Doppler w warunkach podstawowych oraz w czasie wymuszonych zmian ukrwienia mózgu takich jak: zwiększenie całkowitego przepływu krwi pod wpływem wzrostu stężenia dwutlenku węgla we krwi tętniczej oraz zmniejszenie/zwiększenie lokalnego przepływu krwi w wyniku czasowego zamknięcia/udrożnienia tętnicy środkowej mózgu. Przeprowadzono analizę dynamiki zmian rozkładu temperatury wykazując istotną dodatnią korelację tych zmian ze zmianami mikroprzepływu. Otrzymane wyniki potwierdzają możliwość wykorzystania kamery termowizyjnej jako nieinwazyjnej aparatury pomiarowej umożliwiającej oszacowanie zmian ukrwienia mózgu.This study was aimed at verifying the hypothesis that changes in the temperature of the rat brain surface assessed with a thermal imaging camera are correlated with changes of the microflow in cerebral cortex. The experiment was performed on a rat intubated and anaesthetized with 2.5% isoflurane in 30%O2/70%N2O. The SC5600 thermovision camera equipped with a lens with focal length of 54 mm (angle field of view 10° x 8°) and a matrix of cooled detectors InSb 640x480 with a sensitivity of 25 mK was used to record changes in the temperature of the dura matter-covered cerebral cortex, supplied by the middle cerebral artery (MCA). The microflow was measured with a laser-Doppler flowmeter positioned in the same territory [4]. Changes in the microflow (LDF) were elicited either by the increase in CO2 content in the blood or by occlusion/reperfusion of the MCA. Increase in the LDF by 81% during hypercapnia (Fig. 3) was accompanied by the rise in the brain temperature by 0,9 ºC (Fig. 5). During decrease of the LDF by about 80% due to the occlusion of the MCA (Fig. 6), the temperature decreased on average by 0.5 ºC (Fig. 7). Reperfusion resulted in the hyperemia, which was demonstrated as the increase in the LDF by 300% in comparison with the pre-occlusion value and the rise in the brain temperature by 1,6 ºC (Fig. 7). Moreover, a significant correlation was found between the LDF and brain temperature changes (Fig. 8). To the best of our knowledge, this is the first study which directly demonstrates a correlation between the microflow and temperature changes in the brain cortex

Analysis of postural sway in patients with normal pressure hydrocephalus: effects of shunt implantation

<p>Abstract</p> <p>Poor postural balance is one of the major risk factors for falling in normal pressure hydrocephalus (NPH). Postural instability in the clinic is commonly assessed based upon force platform posturography. In this study we focused on the identification of changes in sway characteristics while standing quiet in patients with NPH before and after shunt implantation. Postural sway area and sway radius were analyzed in a group of 9 patients and 46 controls of both genders. Subject's spontaneous sway was recorded while standing quiet on a force platform for 30-60 s, with eyes open and then closed. Both analyzed sway descriptors identified between-group differences and also an effect of shunt implantation in the NPH group. Sway radius and sway area in patients exhibited very high values compared with those in the control group. Importantly, the effect of eyesight in patients was not observed before shunt implantation and reappeared after the surgical treatment. The study documents that static force platform posturography may be a reliable measure of postural control improvement due to shunt surgery.</p

Thermal imaging for intraoperative evaluation of metabolism and brain function – preliminary study

Analiza termiczna powierzchni kory mózgowej ma na celu wyznaczenie granic funkcjonalnie ważnego obszaru kory oraz określenie lokalizacji guzów mózgu zdiagnozowanych innymi metodami obrazowymi. Celem badań jest również znalezienie korelacji pomiędzy stanem klinicznym pacjenta a rejestrowanymi śródoperacyjnie zmianami temperatury powierzchni kory mózgowej. Doświadczenia wstępne przeprowadzone na szczurach miały na celu zbadanie korelacji zmian temperatury powierzchni mózgu ze zmianami mózgowego przepływu krwi. Mózgowy przepływ krwi mierzono za pomocą sondy laserowego przepływomierza dopplerowskiego zarówno w warunkach prawidłowych, jak i w czasie wymuszonych zmian ukrwienia mózgu.Thermal analysis of the cortex surface allows to determine the borders of its functionally important areas and to localize brain tumors that are diagnosed by other imaging methods. The goal of the research is also to check the correlation between the patient's clinical status and temperature changes of the brain surface. Preliminary study conducted on rats aimed to verify the hypothesis that changes in the barin surface temperature correlate with changes of microflow in the cerebral cortex. The microflow was measured with laser Doppler flowmeter both in physiological conditions and during forced changes in cerebral blood supply

The origin of lactate in peritumoral edema as measured by proton-magnetic resonance spectroscopic imaging

Using in vivo proton-magnetic resonance spectroscopy (H-1-MRS), which allows the measurement of metabolites of adequate tissue concentration, the origin of lactate in peritumoral edema has been assessed by comparison with lactate levels in the central and marginal areas of the tumor in 18 patients with cerebral gliomas. In the majority of cases lactate content in the area of peritumoral edema was lower than that in the tumor margin or tumor center, which is consistent with the assumption that the tumor is the source of lactate, which then reaches the surrounding area of edema by diffusion. In 3 of the 18 cases the amount of lactate in the peritumoral edematous tissue was higher than in the tumor, indicating that the lactate is locally produced on account of ischemia due to regional elevation of tissue pressure in the edematous area

Expression of annexin and Annexin-mRNA in rat brain under influence of steroid drugs

Brain tissue of rats pretreated with methylprednisolone or with the 21-aminosteroid U74389F, and that of untreated control rats, was assessed for the expression of Annexin-l (Anx-1) and the transcription of its mRNA. For this purpose Anx-1 cDNA was amplified and simultaneously a T7-RNA-polymerase promotor was incorporated into the cDNA using Polymerase Chain Reaction (PCR). Then digoxigenin-ll-UTP was incorporated into the transcribed cRNA with T7-RNA-polymerase. With this probe ill situ hybridization was carried out in sections of the brain. The probe was visualized by an immunoassay using an anti-digoxigenin antibody conjugate. Anx-1 protein was assessed by means of immunohistochemistry using a polyclonal antibody. The various brain areas of the control animals showed an appreciable amount of Anx-1 at mRNA or protein level; on the other hand, the animals which had been pretreated with either steroid, showed a more intense Anx-1 mRNA signal than the controls in many areas. In the pretreated animals Anx-1 immunostaining was unchanged in cortex, basal ganglia, amygdala and septum, but more intense in hippocampus, hypothalamus and thalamus. In ependyma, choroid plexus, meninges, and vascular walls there was no Anx-1 mRNA transcription detectable. An opposite profile was shown by the Anx-1 immunoreactivity, the protein was present in control animals as well as the steroid-pretreated animals, suggesting that here the protein was either from systemic origin, or has diffused from adjacent structures. The results indicate that Anx-1 mRNA transcription is upregulated by either steroid, and that in the untreated animals there is a resting level of Anx-1 mRNA transcription, presumably reflecting physiological influences on Anx-1 expression