Cerebral perfusion pressure and behavior monitoring in freely moving rats.

Cerebral perfusion pressure (CPP) is the net pressure gradient that drives oxygen delivery to cerebral tissue. It is the difference between the mean arterial pressure (MAP) and the intracranial pressure (ICP). As CPP is a calculated value, MAP and ICP must be measured simultaneously. In research models, anesthetized and acute monitoring is incapable of providing a realistic picture of the relationship between ICP and MAP under physiological and/or pathophysiological conditions. For long-term monitoring of both pressures, the principle of telemetry can be used. The aim of this study was to map changes in CPP and spontaneous behavior using continuous pressure monitoring and video recording for 7 days under physiological conditions (group C - 8 intact rats) and under altered brain microenvironment induced by brain edema (group WI - 8 rats after water intoxication) and neuroprotection with methylprednisolone - MP (group WI+MP - 8 rats with MP 100 mg/kg b.w. applicated intraperitoneally during WI). The mean CPP values in all three groups were in the range of 40-60 mm Hg. For each group of rats, the percentage of time that the rats spent during the 7 days in movement pattern A (standard movement stereotype) or B (atypical movement) was defined. Even at very low CPP values, the standard movement stereotype (A) clearly dominated over the atypical movement (B) in all rats. There was no significant difference between control and experimental groups. Chronic CPP values with correlated behavioral type may possibly answer the question of whether there is a specific, universal, optimal CPP at all.

Determination of brain water content by dry/wet weight measurement for the detection of experimental brain edema.

Brain edema is a fatal pathological state in which brain volume increases as a result of abnormal accumulation of fluid within the brain parenchyma. A key attribute of experimentally induced brain edema - increased brain water content (BWC) - needs to be verified. Various methods are used for this purpose: specific gravimetric technique, electron microscopic examination, magnetic resonance imaging (MRI) and dry/wet weight measurement. In this study, the cohort of 40 rats was divided into one control group (CG) and four experimental groups with 8 rats in each group. The procedure for determining BWC using dry/wet weight measurement was initiated 24 h after the completion of edema induction by the water intoxication method (WI group); after the intraperitoneal administration of Methylprednisolone (MP) together with distilled water during edema induction (WI+MP group); 30 min after osmotic blood brain barrier disruption (BBBd group); after injection of MP via the internal carotid artery immediately after BBBd (BBBd + MP group). While induction of brain edema (WI, BBBd) resulted in significantly higher BWC, there was no increase in BWC in the MP groups (WI+MP, BBBd+MP), suggesting a neuroprotective effect of MP in the development of brain edema.

Effect of methylprednisolone on experimental brain edema in rats - own experience reviewed.

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.

Effect of methylprednisolone on experimental brain edema in magnetic resonance imaging.

Magnetic resonance imaging has been used for evaluating of a brain edema in experimental animals to assess cytotoxic and vasogenic edema by the apparent diffusion coefficient (ADC) and T2 imaging. This paper brings information about the effectiveness of methylprednisolone (MP) on experimental brain edema. A total of 24 rats were divided into three groups of 8 animals each. Rats with cytotoxic/intracellular brain edema induced by water intoxication were assigned to the group WI. These rats also served as the additional control group CG when measured before the induction of edema. A third group (WIMP) was intraperitoneally administered with methylprednisolone 100 mg/kg during water intoxication treatment. The group WI+MP was injected with methylprednisolone 50 mg/kg into the carotid artery within two hours after the water intoxication treatment. We evaluated the results in four groups. Two control groups (CG, WI) and two experimental groups (WIMP, WI+MP). Rats were subjected to MR scanning 24 h after edema induction. We observed significantly increased ADC values in group WI in both evaluated areas - cortex and hippocampus, which proved the occurrence of experimental vasogenic edema, while ADC values in groups WIMP and WI+MP were not increased, indicating that the experimental edema was not developed and thus confirming the protective effect of MP.

TRANSECTION OF INFERIOR ALVEOLAR NERVE IN THE RAT - NEUROANATOMICAL STUDY AND EXPERIMENTAL MODEL.

OBJECTIVE: Experimental lesions in the inferior alveolar nerve (IAN) are used for the study of peripheral and central alterations. The objective of our study was to contribute to a more precise description of the approach to the IAN and creating a lesion. MATERIAL AND METHODS: Twenty-six males of Wistar laboratory rats were used for the study. The animals were divided into three groups: control group (6 rats), experimental group (12 rats - a part of the bone above the mandibular canal was removed under general anaesthesia using extraoral approach, after exposing a part of the IAN, the nerve was excised in a length of 3 mm), and a sham group (8 rats - the nerve was only dissected but not transected). Persisting denervation was verified using surgical revision and histological and immunohistochemical analysis after the observation period (4 weeks). RESULTS: No evidence of re-innervation after 4 weeks. We found no statistically significant differences in mean weight gains between individual groups during the observation period. CONCLUSION: The described technique used in the study is one of the possible ways to create a nerve lesion at the site of the main trunk of the nerve. At the same time, the study provides a more precise description of the anatomical situation and approach to the IAN in the mandibular canal.

Structure assembly regularities in vapour-deposited gold-fullerene mixture films.

Self-assembly is an attractive phenomenon that, with proper handling, can enable the production of sophisticated hybrid nanostructures with sub-nm-scale precision. The importance of this phenomenon is particularly notable in the fabrication of metal-organic nanomaterials as promising substances for spintronic devices. The exploitation of self-assembly in nanofabrication requires a comprehension of atomic processes creating hybrid nanostructures. Here, we focus on the self-assembly processes in the vapour-deposited Au x C60 mixture films, revealing the exciting quantum plasmon effects. Through a systematic characterization of the Au x C60 films carried out using structure-sensitive techniques, we have established correlations between the film nanostructure and the Au concentration, x. The analysis of these correlations designates the Au intercalation into the C60 lattice and the Au clustering as the basic processes of the nanostructure self-assembly in the mixture films, the efficiency of which strongly depends on x. The evaluation of this dependence for the Au x C60 composite nanostructures formed in a certain composition interval allows us to control the size of the Au clusters and the intercluster spacing by adjusting the Au concentration only. This study represents the self-assembled Au x C60 mixtures as quantum materials with electronic functions tuneable by the Au concentration in the depositing mixture.

Forelimb Movement Disorder in Rat Experimental Model.

Study of motor activity is an important part of the experimental models of neural disorders of rats. It is used to study effects of the CNS impairment, however studies on the peripheral nervous system lesions are much less frequent. The aim of the study was to extend the spectrum of experimental models of anterior limb movement disorders in rats by blockade of the right anterior limb brachial plexus with the local anesthetic Marcaine (Ma), or with aqua for injection administered into the same location (Aq) (with control intact group C). Two other groups with anterior limb movement disorders underwent induction of cellular brain edema by water intoxication (MaWI and AqWI). Results showed a lower spontaneous motor activity of animals in all experimental groups versus controls, and lower spontaneous motor activity of animals in the MaWI group compared to other experimental groups in all categories. There was no difference in spontaneous activity between the groups Ma, Aq and AqWI. Our study indicates that alterations of spontaneous motor activity may result from the impaired forelimb motor activity induced by the anesthetic effect of Marcaine, by the volumetric effect of water, as a result of induced brain edema, or due to combination of these individual effects.

Loss of body weight is accompanying cellular brain edema induced by water intoxication in the rat.

Induction of cellular cerebral edema (CE) was achieved by a standard method of water intoxication which consisted of fractionated intraperitoneal administration of distilled water (DW) together with the injection of desmopressin (DP). Using metabolic cage, fluid and food balance was studied in two groups of eight animals: group C - control; group CE - cellular edema induced by water intoxication. For each rat the intake (food pellets and water) and excretion (solid excrements and urine) were recorded for 48 h together with the initial and final body weight. CE animals consumed significantly less food, drank less water and eliminated the smallest amount of excrements. The induction of cellular cerebral edema was accompanied with a significant loss of body weight (representing on average 13 % of the initial values) mainly due to a reduction of food intake. This phenomenon has not yet been reported.

Multielemental Chemical Analysis of Elements in Mandibular Bone and Teeth in the Rat.

The purpose of the study was to test the hypothesis of different distribution spaces of elements in the rat mandibular bone and teeth. We used six adult males of Wistar laboratory rats for the study. After killing the animals, we extracted the molars and removed incisor crowns. The mandibular bone was divided into four parts (mesial-central-distal-ridge). Inductively coupled plasma mass spectrometry was used to determine the presence of 41 elements in the bone and tooth. Evidence of 14 elements was found in all samples (incisors-molarsbone). Generally, significant differences between the left and right side were found for K and Rb in the bone locations. As regards statistically significant differences in incisors-molars-bone locations, the elements for which these differences were found for all comparisons are listed as incisors versus individual molars, incisors versus bone locations, and individual molars versus bone locations: a) incisors-molars: Ba, Mn, Mo, Sr, Zn, K, Mg and Rb; b) incisors-bone: Fe, K, Mg, Mn, Na, Zn and Ba; c) molars-bone: Mn, Mo, Na and Mg. Statistically significant differences were also found between molars for Fe, Mg, Mn, and Sr and between bone locations for Ba, Ca, Mn, Sr, K, Rb, Zn, Mo, Mg, and Na. The elements Cu, Ni and Co were without pronounced differences. Twenty-seven elements were below the detection limit. Our results indicate different distributions of some elements in the rat mandibular incisors-molars-bone. We assume that the knowledge of chemical element contents in the laboratory rat bone and teeth will prove useful in experimental research of both these hard tissues.

Multielemental Chemical Analysis of Elements in Mandibular Bone and Teeth in the Rat.

The original article was published in Folia Biologica (Praha) Volume 64, No. 3 (2018), 84-96.

Observation of dielectric universalities in albumin, cytochrome C and Shewanella oneidensis MR-1 extracellular matrix.

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.

Methylprednisolone modulates intracranial pressure in the brain cellular edema induced by water intoxication.

Continuous monitoring of the intracranial pressure (ICP) detects impending intracranial hypertension resulting from the impaired intracranial volume homeostasis, when expanding volume generates pressure increase. In this study, cellular brain edema (CE) was induced in rats by water intoxication (WI). Methylprednisolone (MP) was administered intraperitoneally (i.p.) before the start of CE induction, during the induction and after the induction. ICP was monitored for 60 min within 20 h after the completion of the CE induction by fibreoptic pressure transmitter. In rats with induced CE, ICP was increased (Mean+/-SEM: 14.25+/-2.12) as well as in rats with MP administration before the start of CE induction (10.55+/-1.27). In control rats without CE induction (4.62+/-0.24) as well as in rats with MP applied during CE induction (5.52+/-1.32) and in rats with MP applied after the end of CE induction (6.23+/-0.73) ICP was normal. In the last two groups of rats, though the CE was induced, intracranial volume homeostasis was not impaired, intracranial volume as well as ICP were not increased. It is possible to conclude that methylprednisolone significantly influenced intracranial homeostasis and thus also the ICP values in the model of cellular brain edema.

Signs of myelin impairment in cerebrospinal fluid after osmotic opening of the blood-brain barrier in rats.

A number of clinical neurological pathologies are associated with increased permeability of the blood brain barrier (BBB). Induced changes of the homeostatic mechanisms in the brain microenvironment lead among others to cellular changes in the CNS. The question was whether some of these changes can be induced by osmotic opening of BBB in an in vivo experiment and whether they can be detected in cerebrospinal fluid (CSF). CSF was taken via the suboccipital puncture from 10 healthy rats and six rats after the osmotic opening of the BBB. In all 16 animals, concentration of myelin basic protein (MBP ng/ml), Neuron-specific enolase (NSE ng/ml) and Tau-protein (Tau pg/ml) were determined in CSF by ELISA. Values in both groups were statistically evaluated. Significant difference between the control and experimental group was revealed only for the concentration of myelin basic protein (p<0.01). The presented results indicate that osmotic opening of the BBB in vivo experiment without the presence of other pathological conditions of the brain leads to a damage of myelin, without impairment of neurons or their axons.

Subconvulsive dose of kainic acid transiently increases the locomotor activity of adult Wistar rats.

Kainic acid (KA) is a potent neurotoxic substance valuable in research of temporal lobe epilepsy. We tested how subconvulsive dose of KA influences spontaneous behavior of adult Wistar rats. Animals were treated with 5 mg/kg of KA and tested in Laboras open field test for one hour in order to evaluate various behavioral parameters. Week after the KA treatment animals were tested again in Laboras open field test. Finally, rat's brains were sliced and stained with Fluoro-Jade B to detect possible neuronal degeneration. Treatment with KA increased the time spent by locomotion (p<0.01), exploratory rearing (p<0.05) and animals traveled longer distance (p<0.01). These parameters tended to increase thirty minutes after KA administration. Week after the treatment we did not found differences in any measured behavioral parameter. Histology in terms of Fluoro-Jade B staining did not reveal any obvious neuronal damage in hippocampus. These results demonstrate that subconvulsive KA dose changes the behavioral parameters only transiently. Clarification of timing of the KA induced changes may contribute to understand mutual relationship between non-convulsive seizures and behavioral/cognitive consequences.

Low dose domoic acid influences spontaneous behavior in adult rats.

Domoic acid (DA) is a potent marine neurotoxine present in seafood. Intoxication by DA causes gastrointestinal symptoms like vomiting and diarrhoea and also the so-called amnesic shellfish poisoning (inflicting memory impairment and seizures). Since exposure to non-convulsive doses is relevant to the human health, we investigated the effect of low dose DA administration in adult Wistar rats. Rats were administered with DA at the dose 1.0 mg/kg and their behavior was monitored for one hour in three sessions. The first session started immediately after DA administration. The second and third session started one and two weeks later. After the third session, the histochemical analysis of the hippocampi of the animals was conducted (Fluoro-Jade B, bis-benzimide). DA increased time spent by locomotion and distance travelled in the second half of the first session and this effect was pronounced during the second and third session. Exploratory rearing was decreased by DA administration in the first half of the first session. DA influenced the grooming in biphasic manner (decrease followed by an increase of time spent by grooming). This biphasic trend was observed even two weeks after the DA administration. Histochemistry of DA treated rats did not confirm the presence of apoptotic bodies, Fluoro-Jade B positive cells were not found neither in CA1 nor CA3 area of the hippocampi. Our study revealed that a low dose of DA affect short and long-term the spontaneous behavior of rats without inducing neuronal damage.

Influence of low-dose neonatal domoic acid on the spontaneous behavior of rats in early adulthood.

Consumption of seafood containing toxin domoic acid (DA) causes an alteration of glutamatergic signaling pathways and could lead to various signs of neurotoxicity in animals and humans. Neonatal treatment with domoic acid was suggested as valuable model of schizophrenia and epilepsy. We tested how repeated early postnatal DA administration influences the spontaneous behavior of rats in adulthood. Rats were injected with 30 microg DA/kg from postnatal day (PND) 10 until PND 14. Their behavior was observed in the open field test for one hour (Laboras, Metris) at PND 35, PND 42 and PND 112. We did not find any difference between DA treated rats and animals injected with equivalent volume of saline in both test sessions at PND 35 and PND 42. DA rats at PND 112 exhibited significantly higher vertical and horizontal exploratory activity (tested parameters: locomotion, distance travelled, average speed reached during test, grooming and rearing) between the 30th-40th min of the test session and habituated over 10 min later. We conclude that at least in the given experimental design, neonatal DA treatment results in alteration of the spontaneous behavior of rats in adulthood.

CT imaging and spontaneous behavior analysis after osmotic blood-brain barrier opening in Wistar rat.

In our previous experiments we demonstrated that osmotic opening of the blood brain barrier (BBB) in rats by administration of mannitol into the internal carotid artery leads to cerebral edema. The aim of this study was to confirm objectively the development of brain edema and determine whether it affects spontaneous locomotor activity in rats (SLA). Brain edema was verified by computer tomography (CT) examination of the brain and SLA was observed during open field test. Twenty four adult male rats were divided into four groups of six: (1) control animals (C), (2) controls with anesthesia (CA), (3) controls with sham surgery (CS), (4) experimental - osmotic opening of the BBB (MA). Osmotic BBB disruption manifested by reducing the density of brain tissue (hypodensity), suggesting a higher water content in the brain tissue. SLA was compared between C, CA, CS and MA groups and between MA and CA groups. Significant difference was found only between the control group and MA group. In the first 30 min of the examination, rats after the mannitol administration revealed a marked limitation of spontaneous locomotor activity. Experimental results demonstrated reduction of spontaneous locomotor activity in rats with induced brain edema.

Both water intoxication and osmotic BBB disruption increase brain water content in rats.

Our previous experiments revealed that water intoxication and osmotic BBB disruption in the rat allow penetration of high-molecular substances into the brain and that resulting changes in the internal environment of the CNS lead to pathological development, such as the loss of integrity of myelin. The aim of the present study was to determine whether the previously described phenomena are associated with increased water content in the brain. To answer the question following methods were used: a) water intoxication: intraperitoneal administration of distilled water, b) osmotic BBB disruption: application of mannitol (20 %) selectively into the internal carotid artery, c) brain wet weight was measured after decapitation, and subsequently (after six days in thermostat set at 86 °C) the dry weight were estimated d) in animals with 20 % and 30 % hyperhydration the degree of myelin deterioration was estimated e) animal locomotor activity was tested by continuous behavior tracking and analysis. Brain water content after water intoxication and following the administration of mannitol was higher than in the control group. Different degrees of hyperhydration led to different levels of brain water content and to different degrees of myelin impairment. Hyperhydration corresponding to 20 % of the body weight brought about lower locomotor activity. Increased water content in the brain after the BBB osmotic disruption is surprising because this method is frequently used in the clinical practice.

Fast and delayed locomotor response to acute high-dose nicotine administration in adult male rats.

The aim of the present study was to compare the immediate and delayed locomotor response to high-dose nicotine (NIC) administration in rats. The vertical and horizontal activity of behavior in adult male rats exposed to 1 mg/kg NIC or saline (SAL) were tested in a Laboras apparatus for one hour after drug application. Animals were then returned to their cages and housed for another seven days. After this period all animals were placed in Laboras again and their behavioral pattern was retested for another period of one hour (delayed response). Horizontal activity: immediately after nicotine administration animal were less mobile (first 2-minutes interval), when compared with controls. The immobilization effect of nicotine disappeared within 4 minutes and during whole first 10-minutes interval time spent by locomotion did not differ from controls. Locomotion activity of animals treated with nicotine increased robustly in following 10 minutes and remained significantly higher in 2nd, 3rd and 5th 10-minutes interval. Vertical activity: Rearing frequency was significantly lowered by NIC administration in first two minutes of the experiment and the same was found when the duration of rearing was analyzed. Lower rearing intensity of NIC treated animals disappeared in 4 minutes and was finally higher during whole test session as compared with controls. When duration of rearing was analyzed it was significantly longer in NIC treated animals. In majority of observed behavioral aspects there were no differences between NIC treated rats and controls seven days after NIC or SAL treatment. Our results reflect effect of NIC and we conclude that NIC significantly influences behavior of experimental animals.

[Comparison of patellar pain after total knee arthroplasty with conventional versus individual femoral rotational alignment]. / Srovnání výskytu patelární bolesti po aloplastice kolenního kloubu u konvencne nebo individuálne nastavené rotace femorální komponenty.

PURPOSE OF THE STUDY: The aim of the study was to find out whether the frequency and intensity of patellar pain can be affected by individual rotational alignment of the femoral component in total knee arthroplasty, as compared with the standard 3 degrees of external femoral rotation in conventional procedures. MATERIAL AND METHODS: In randomly selected patients treated for knee osteoarthritis by total joint replacement between January 2007 and January 2011, the occurrence of patellar pain was assessed. The evaluated knees were allocated to two groups. Group 1 included 350 knee joints with conventional femoral rotational alignment, i.e., 3 degrees of external rotation. Group 2 comprised 380 knee joints with an individual rotational alignment of the femoral component based on the condylar twist angle. Post-operative anterior knee pain was assessed on the following scale: 1, no pain; 2, occasional mild pain; 3, moderate pain; 4, severe pain. RESULTS: In group 1, 312 knee joints were free from pain, 15 occasionally experienced mild pain, 15 had moderate and eight had severe pain. A total of 23 revision operations were performed for patellar pain at the anterior knee and pain around the patella refractory to non-steroidal anti-rheumatic and rehabilitation therapy. In group 2, there were 331 pain-free knees, 48 with occasional mild pain, one with moderate pain and no knee with severe pain. No revision surgery was required. One patient with moderate patellar pain underwent surgery for spinal canal stenosis; after that knee pain was only mild. The groups were compared, as to pain assessment results, using the test of equality of relative frequencies, i.e., score categories 1+2 versus 3+4 of 350 (group 1) equalled 23 (6.57%) were compared with 1 (0.26%) of 380 (group 2); the difference was significant (p < 0.001). Using the same test for comparison of the frequency of repeat operations, i.e., 23 (0.57%) of 350 (group 1) versus 0 (0%) of 380 (group 2), also gave a significant result (p = 0.001). DISCUSSION: Mild and occasional pain was recorded in both groups, suggesting that femoral component malrotation is not the only cause of patellar pain following total knee arthroplasty. A markedly lower incidence of moderate and severe pain and no need for revision surgery found in group 2 provides evidence that the use of individual rotational alignment of the femoral component is fully justified. CONCLUSIONS: An individual rotational alignment of the femoral component can significantly reduce the incidence of moderate to severe patellar pain or even need for revision surgery.