Animal models are an important tool for studying ischemic mechanisms of stroke. Among them, the middle cerebral artery occlusion (MCAO) model via the intraluminal suture method in rodents is closest to human ischemic stroke. It is a model of transient occlusion followed by reperfusion, thus representing cerebral ischemia-reperfusion model that simulates patients with vascular occlusion and timely recanalization. Although reperfusion is very beneficial for the possibility of preserving brain functions after ischemia, it also brings a great risk in the form of brain edema, which can cause the development of intracranial hypertension, and increasing morbidity and mortality. In this paper, we present the results of our own transient reperfusion model of MCAO in which we tested the permeability of the blood-brain barrier (BBB) using Evans blue (EB), an intravital dye with a high molecular weight (68,500 Da) that prevents its penetration through the intact BBB. A total of 15 animals were used in the experiment and underwent the following procedures: insertion of the MCA occluder; assessment of ischemia by 2,3,5 -Triphenyltetrazolium chloride (TTC) staining; assessment of the BBB permeability using brain EB distribution. The results are presented and discussed. The test of BBB permeability using EB showed that 120 minutes after induction of ischemia, the BBB is open for the entry of large molecules into the brain. We intend to use this finding to time the application of neuroprotective agents via ICA injection in our next stroke model. Keywords: Cerebral ischemia-reperfusion model, Middle cerebral artery occlusion, Blood-brain barrier, 2,3,5 -Triphenyltetrazolium chloride, Evans blue.
- MeSH
- Evansova modř MeSH
- hematoencefalická bariéra * metabolismus MeSH
- infarkt arteria cerebri media * metabolismus MeSH
- ischemie mozku metabolismus MeSH
- kapilární permeabilita MeSH
- krysa rodu rattus MeSH
- modely nemocí na zvířatech * MeSH
- permeabilita MeSH
- pilotní projekty MeSH
- potkani Sprague-Dawley MeSH
- reperfuzní poškození * metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Brain edema - a frequently fatal pathological state in which brain volume increases resulting in intracranial pressure elevation - can result from almost any insult to the brain, including traumatic brain injury. For many years, the objective of experimental studies was to find a method to prevent the development of brain edema at the onset. From this perspective, the use of methylprednisolone (MP) appears promising. High molecular MP (MW>50 kDa) can be incorporated into the brain - in the conditions of the experimental model - either by osmotic blood-brain barrier disruption (BBBd) or during the induction of cellular edema by water intoxication (WI) - a condition that increases the BBB permeability. The time window for administration of the MP should be at the earliest stages of edema. The neuroprotective effect of MP on the permeability of cytoplasmatic membranes of neuronal populations was proved. MP was administrated in three alternative ways: intraperitoneally during the induction of cytotoxic edema or immediately after finishing cytotoxic edema induction in a dose of 100 mg/kg b.w.; into the internal carotid artery within 2 h after finishing cytotoxic edema induction in a dose of 50 mg/kg b.w.; into internal carotid artery 10 min after edema induction by BBBd in a dose of 50 mg/kg b.w.
- MeSH
- edém mozku farmakoterapie metabolismus patologie MeSH
- glukokortikoidy farmakologie MeSH
- hematoencefalická bariéra účinky léků metabolismus patologie MeSH
- kapilární permeabilita účinky léků MeSH
- krysa rodu rattus MeSH
- methylprednisolon farmakologie MeSH
- modely nemocí na zvířatech MeSH
- mozek účinky léků metabolismus patologie MeSH
- neurony účinky léků metabolismus patologie MeSH
- neuroprotektivní látky farmakologie MeSH
- potkani Wistar MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The electrodynamics of metals is well understood within the Drude conductivity model; properties of insulators and semiconductors are governed by a gap in the electronic states. But there is a great variety of disordered materials that do not fall in these categories and still respond to external field in an amazingly uniform manner. At radiofrequencies delocalized charges yield a frequency-independent conductivity σ 1(ν) whose magnitude exponentially decreases while cooling. With increasing frequency, dispersionless conductivity starts to reveal a power-law dependence σ 1(ν)∝ν s with s < 1 caused by hopping charge carriers. At low temperatures, such Universal Dielectric Response can cross over to another universal regime with nearly constant loss ε″∝σ1/ν = const. The powerful research potential based on such universalities is widely used in condensed matter physics. Here we study the broad-band (1-1012 Hz) dielectric response of Shewanella oneidensis MR-1 extracellular matrix, cytochrome C and serum albumin. Applying concepts of condensed matter physics, we identify transport mechanisms and a number of energy, time, frequency, spatial and temperature scales in these biological objects, which can provide us with deeper insight into the protein dynamics.
- MeSH
- albuminy metabolismus MeSH
- cytochromy c metabolismus MeSH
- elektrická vodivost MeSH
- elektřina * MeSH
- extracelulární matrix metabolismus MeSH
- Shewanella metabolismus MeSH
- skot MeSH
- spektrální analýza MeSH
- teplota MeSH
- voda chemie MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- fyziologie MeSH
- společnosti vědecké MeSH
- Publikační typ
- zprávy MeSH
- Geografické názvy
- Česká republika MeSH
We assessed blood-brain barrier (BBB) disruption in early stage of photothrombotic focal cerebral ischemia in the rat. We specifically looked for contralateral changes in BBB permeability and tested the influence of two anesthetics on the results. Adult Wistar rats were randomly anesthetized with pentobarbital (PB) or ketamine-xylazine (KX). Rats received intravenously (i.v.) Rose Bengal followed by Evans Blue (EB). Stereotactically defined spots on denuded skull were irradiated by laser (532 nm) for 18 min. Twenty four hours later, rats were killed, brains perfused, fixated, sectioned and slices analyzed by fluorescence microscopy. Volume of necrosis and volume of EB-albumin extravasation were calculated. Evidence of BBB breakdown in remote brain areas was sought and compared to sham handled controls. BBB disruption was consistently present, frequently with EB-albumin accumulating cells. Total lesion volume did not significantly differ among groups (TLVPB=9.4±1.3 mm³ vs. TLVKX=8.3±2.1 mm³); same was true for the volume of necrosis (NVPB=5.1±0.7 mm³ vs. NVKX=6.3±1.9 mm³). However, volume of EB-albumin extravasation area was significantly smaller in KX group (EBEVPB=4.3±0.8 mm³ vs. EBEVKX=2.0±0.5 mm³; p=0.0293). Median background EB-fluorescence signal density was higher in PB group (p<0.0001). Furthermore, regional increase in EB-fluorescence was found in two animals in PB group. Our study shows that anesthesia with NMDA-antagonist ketamine and α2-adrenergic agonist xylazine may reduce BBB breakdown in photothrombosis. Pentobarbital anesthesia lead to increased BBB permeability in the contralateral hemisphere.
- MeSH
- alfa-2-adrenergní receptory - agonisté farmakologie MeSH
- anestetika farmakologie MeSH
- antagonisté excitačních aminokyselin farmakologie MeSH
- hematoencefalická bariéra účinky léků patologie MeSH
- hypnotika a sedativa farmakologie MeSH
- intrakraniální trombóza patologie MeSH
- ischemie mozku patologie MeSH
- ketamin farmakologie MeSH
- krysa rodu rattus MeSH
- lasery MeSH
- nekróza patologie MeSH
- pentobarbital farmakologie MeSH
- potkani Wistar MeSH
- receptory N-methyl-D-aspartátu antagonisté a inhibitory MeSH
- sloučeniny dusíkatého yperitu farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Microtubules are important structures in the cytoskeleton, which organizes the cell. Since microtubules are electrically polar, certain microtubule normal vibration modes efficiently generate oscillating electric field. This oscillating field may be important for the intracellular organization and intercellular interaction. There are experiments which indicate electrodynamic activity of variety of cells in the frequency region from kHz to GHz, expecting the microtubules to be the source of this activity. In this paper, results from the calculation of intensity of electric field and of radiated electromagnetic power from the whole cellular microtubule network are presented. The subunits of microtubule (tubulin heterodimers) are approximated by elementary electric dipoles. Mechanical oscillation of microtubule is represented by the spatial function which modulates the dipole moment of subunits. The field around oscillating microtubules is calculated as a vector superposition of contributions from all modulated elementary electric dipoles which comprise the cellular microtubule network. The electromagnetic radiation and field characteristics of the whole cellular microtubule network have not been theoretically analyzed before. For the perspective experimental studies, the results indicate that macroscopic detection system (antenna) is not suitable for measurement of cellular electrodynamic activity in the radiofrequency region since the radiation rate from single cells is very low (lower than 10⁻²⁰ W). Low noise nanoscopic detection methods with high spatial resolution which enable measurement in the cell vicinity are desirable in order to measure cellular electrodynamic activity reliably.
- MeSH
- biologické hodiny fyziologie MeSH
- biologické modely MeSH
- buněčná membrána fyziologie MeSH
- centrozom fyziologie MeSH
- elektromagnetická pole MeSH
- membránové potenciály fyziologie MeSH
- mikrotubuly fyziologie MeSH
- polarita buněk fyziologie MeSH
- vibrace MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
