Lithium-pilocarpine status epilepticus (SE) resulted in delayed changes of single cortical in terhemisperic (transcallosal) responses in immature rats. Low-frequency stimulation inducing depression and/or potentiation was studied to analyze possible dynamic changes in cortical responses. Status was elicited in 12-day-old (SE12) or 25-day-old (SE25) rats. Control siblings received saline instead of pilocarpine. Interhemispheric responses were elicited by stimulation of the sensorimotor region of the cerebral cortex 3, 6, 9, 13, or 26 days after status. A series of 5 biphasic pulses with intensity equal to twofold threshold were used for stimulation. The interval between pulses was 100, 125, 160, 200 or 300 ms, eight responses were always averaged. Peak amplitude of the first positive, first negative and second positive waves was measured and responses to the second, third, fourth and fifth pulse were compared with the first one. Animals after status epilepticus as well as lithium-paraldehyde controls exhibit a frequency depression at nearly all the intervals studied. An outlined increase of responses in SE rats in comparison with the controls three days after SE stayed just below the level of statistical significance. In addition, animals in the SE12 group exhibited potentiation of responses at this interval after SE. With longer intervals after SE, the relation between SE and control animals changed twice resulting in a tendency to lower amplitude of responses in SE than in control rats 26 days after SE. Rats in the SE25 group exhibited higher responses than controls 13 days after status, but this difference was not present at the longest interval after SE. Low-frequency stimulation did not reveal increased cortical excitability as a long-lasting consequence of status epilepticus induced in immature rats. In addition, the outlined differences between SE and control rats changed with the time after SE., G. Tsenov, P. Mareš., and Obsahuje bibliografii a bibliografické odkazy
Recent observations suggest the presence of 20S proteasomes (20S) in the lung epithelial lining fluid. However, the physiological relevance of 20S in the alveolar space and possible contribution to disease processes are unknown. Thus, we evaluated whether extracellular proteasomes could have a pathophysiological role in the injured lung using a rat model of lung contusion (LC). Bronchoalveolar lavage fluids (BALF) were obtained at various time points for up to 168 h after LC or sham procedure. Enzyme activities, ELISA and Western blots indicated enzymatically active 20S, the 19S subunit Rpt5 and ubiquitin in BALF. 20S and ubiquitin increased significantl y after LC, peaked at 24 h and normalized within 168 h. Mg 2+ /ATP-dependent peptidase activities were detectable 6-24 h after LC. BALF after LC also contained ubiquitin-protein-ligase activity. Addition of Mg 2+ /ATP to BALF after LC led to significant proteolysis and could be prevented with epoxomicin and EDTA. These data suggest for the first time that the Mg 2+ /ATP-dependent 26S proteasome complex exists outside the cell, is released into the lung epithelial lining fluid after LC and contribute s to the proteolysis of the bulk of protein in the alveolar space of the injured lung. We infer that proteasome complexes may have a pathophysiological role during lung edema clearance., M. Majetschak, L. T. Sorell, T. Patricelli, D. H. Seitz, M. W. Knöferl., and Obsahuje bibliografii
Many physiological and pathological processes in the cardiac tissue have been shown to be associated with a release of endothelin (ET) peptides and with induction of specific ET-receptors and G-protein-coupled ion channels. However, the exact mechanism regulating ET-receptors in the myocardium is controversial. The response to ET-1, the most important member of the ET family, is rapidly attenuated by down-regulation of ET-receptors. The internalization of ET-1 bound to two subclasses of specific receptors (ETA and ETB) that are abundant in the myocardium has been hypothesized to activate and/or inhibit a variety of intracellular signal transducing systems. The [125I]ET-1, BQ-3020 and selective ET-antagonists were used to study the subtype-selective component of regulation of ET-1 receptors in myocardial membranes. We determined the characteristics of [125I]ET-1 binding and [3H]thymidine incorporation in whole cell saturation studies and measured Ca 2+ channel induction and the total number of inactive Ca2+ channels in photoaffinity studies with [3H]azidopine. Here we demonstrate four important components of the complex ET-1 response in human, porcine and rat myocardium, leading to aberrant responses of cells. After ET-1 induction, adaptive subtype-ETB selective down-regulation predominated in human embryonic fibroblasts, in porcine membrane vesicles and in microsomal membranes of renal hypertensive rats, with preferential high affinity ET-1 binding to ETA receptors and with the resultant ETA mediated proliferative and mitogenic activation of human fibroblasts. The ET-1 induction was also accompanied by profound inactivation of Ca2+ channels in myocardial membranes., J. Dřímal, M. Mislovičová, A. Ismail, F. Monček., and Obsahuje bibliografii
We have examined the changes of intercellular electrical coupling protein connexin-43 (Cx43) and of PKC-ε in heart atria of diabetic rats and/or after the treatment with triiodothyronine (T3 ). Diabetes was induced in Wistar-Kyoto rats by streptozotocin (50 mg/kg, i.v.) and atria were examined after 5 (acute stage) and 10 (chronic stage) weeks. T 3 (10 μg/100 g/day) was applied via a gastric tube for the last 10 days prior to the end of the experiments to non-diabetic and to the half of diabetic rats. Expression and phosphorylated status of Cx43, as well as expression of PKC-ε , were analyzed by Western blots using mouse monoclonal anti-Cx43 and rabbit polyclonal anti-PKC-ε antibodies. We found that the Cx43 expression was significantly increased after the treatment with T3 and in the acute diabetes. Both in diabetes and after T3 treatment the phosphorylation of Cx43 isoforms was markedly suppressed compared to the non-diabetic and T3-untreated controls. Such a down-regulation was less pronounced in diabetic rats after the T3-treatment. The expression of atrial PKC-ε was increased in diabetic rats. This increase was suppressed after T3 administration and the expression was decreased in T3-treated non-diabetic rats. We suggest that the reduced Cx43 phosphorylation in diabetic and hyperthyroid rats can deteriorate a cell-to-cell coupling and consequently facilitate a development of atrial tachyarrhythmia in diabetic or hyperthyroid animals., M. Mitašíková ... [et al.]., and Obsahuje seznam literatury
We have found that the determination of thiodiglycolic acid (TDGA) in urine may help to characterize metabolic imbalance of substances participating in methionine synthesis, which leads to hyperhomocystinuria. From the metabolic scheme, based on a proper combination of known facts, we attempted to theoretically explain and to demonstrate the possibilities of TDGA formation via different ways of homocysteine transformation. This scheme was used in evaluating the results obtained by testing urine of a woman suffering from impaired function of methionine synthase reductase (CblE type of homocystinuria). The amount of TDGA excreted in her morning urine was very sensitive to the changes in her treatment based upon a combination of N5-formyl tetrahydrofolate, betaine and vitamin B12. Vitamin B12 given in the evening either alone or together with betaine increased the TDGA excretion in the morning urine up to ten times. On the other hand, in the absence of vitamin B12, betaine in combination with N5-formyl tetrahydrofolate hindered the appearance of TDGA in the morning urine. Generally, the determination of TDGA in urine of an appropriately pretreated patient may indicate the degree of success of the treatment., T. Navrátil, M. Petr, Z. Šenholdová, K. Přistoupilová, T. I. Přistoupil, M. Heyrovský, D. Pelclová, E. Kohlíková., and Obsahuje bibliografii a bibliografické odkazy
Derivative of 6-methyluracil, selective cholinesterase inhibitor C-547 potentiates miniature endplate currents (MEPCs) in rat external intercostal muscles (external ICM) more effectively than in internal intercostal muscles (internal ICM). Effect of the C-547 on intercostal muscles was compared with those on extensor digitorum longus (EDL) and diaphragm muscles. Half-effective concentrations for τ of MEPC decay arranged in increasing order were as follows: EDL, locomotor muscle, most sensitive = 1.3 nM, external ICM, inspiration muscle = 6.8 nM, diaphragm, main inspiration muscle = 28 nM, internal ICM, expiration muscle = 71 nM. External ICM might therefore be inhibited, similarly as the limb muscles, by nanomolar concentrations of the drug and do not participate in inspiration in the presence of the C-547. Moreover, internal ICM inhibition can hinder the expiration during exercise-induced fast breathing of C-547-treated experimental animals., K. Petrov ... [et al.]., and Obsahuje seznam literatury
Microvessels respond to metabolic stimuli (e.g. pO2) and hemodynamic forces (e.g. shear stress and wall stress) with structural adaptations including angiogenesis, remodeling and pruning. These responses could be mediated by differential gene expression in endothelial and smooth muscle cells. Therefore, rat mesenteric arteries and veins we reexcised by microsurgery, and mRNA expression of four angioadaptation-related genes was quantified by real time duplex RT-PCR in equal amounts of total RNA, correlated to two different house keeping genes (ß-actin, GAPDH). The results show higher expression of VEGFA, TIE2, and ANG2 in arteries than in veins, but equal expression of ADAMTS1. Higher availability of VEGFA mRNA in endothelial cells of arteries shown here could contribute to the maintenance of mechanically stressed blood vessels and counteract pressure-induced vasoconstriction., N. Mecha Disassa ... [et al.]., and Obsahuje seznam literatury
The nucleus accumbens (NAc) core is critical in the control of motivated behaviors. The muscarinic acetylcholine receptors (mAChRs) modulating the excitatory inputs into the NAc core have been reported to impact such behaviors. Recent studies suggest that ventral and dorsal regions of the NAc core seem to be innervated by distinct popula tions of glutamatergic projection neurons. To further examine mAChRs modulation of these glutamatergic inputs to the NAc core, we employed intracellular recordings in rat NAc coronal slice preparation to characterize: 1) the effects of muscarine, an mAChRs agonist, on membrane properties of the NAc core neurons; 2) depolarizing synaptic potentials (DPSP) elicited by ventral and dorsal focal electrical stimuli; and 3) paired-pulse response with paired-pulse stimulation. Here we report that the paired-pulse ratio (PPR) elicited by dorsal stimuli was grea ter than that elicited by ventral stimuli. Bath application of muscarine (1-30 μ M) decreased both ventral and dorsal DPSP in a concentration-dependent manner, with no effect on electrophysiological properties of NAc core neurons. Muscarine at 30 μ M also elicited larger depression of dorsal DPSP than ventral DPSP. Moreover, muscarine increased the PPR of both dorsal and ventral DPSP. These data indicate that the glutamatergic afferent fibers traversing the dorsal and ventral NAc are separate, and that differential decrease of distinct afferent excitatory neurotransmission onto NAc core neurons may be mediated by presynaptic mechanisms., X. Jiang ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The glycophenotyping of mammalian cells with plant lectins maps aspects of the glycomic profile and disease-associated alterations. A salient step toward delineating their functional dimension is the detection of endogenous lectins. They can translate sugar-encoded changes into cellular responses. Among them, the members of the lectin family of galectins are emerging regulators of cell adhesion, migration and proliferation. Focusing on galectins-1, -3 and -7, we addressed the issue whether their expression is regulated during wound healing in porcine skin as model. A conspicuous upregulation is detected for galectin-1 in the dermis and a neoexpression in the epidermis, where an increased level of galectin-7 was also found. Applying biotinylated tissue lectins as probes, the signal intensities for accessible binding sites decreased, intimating an interaction of the cell lectin with reactive sites. In contrast, galectin-3 parameters remained rather constant. Of note, epidermal cells in culture also showed an increase in expression/presence of galectin-1, measured on the levels of mRNA and protein, in this case by Western blotting and quantitative immunocytochemistry. Used as matrix, galectin-1 conferred resistance to trypsin treatment to attached human keratinocytes and reduced migration into scratch-wound areas in vitro. This report thus presents new information on endogenous lectins in wound healing and differential regulation among the three tested cases., J. Klíma ... [et al.]., and Obsahuje seznam literatury
The activity of 194 neurons was recorded in three subdivisions of the medial geniculate body (74 neurons in the ventral, 62 in the medial and 44 neurons in the dorsal subdivision, i.e. vMGB, mMGB and dMGB) of guinea pigs anesthetized with ketamine-xylazine. The discharge properties of neurons were evaluated by means of peristimulus time histograms (PSTHs), interval histograms (INTHs) and auto-correlograms (ACGs). In the whole MGB, the most frequent PSTH responses to pure tone stimuli were onset (43 %) or chopper (32 %). The onset responses were mostly present in the vMGB, whereas chopper responses dominated in the dMGB. In the whole MGB Poisson-like and bimodal INTHs were found in 46 % and 40 % of neurons, respectively. The mMGB revealed fewer bimodal and more symmetrical types of INTH. In the whole MGB, 60 % of units were found to have ACGs typical for short bursts (<100 ms), 23 % for long bursts (>100 ms) and 15 % of units fired without bursts. Neurons in the vMGB were characterized by short bursting, whereas those in the mMGB and dMGB expressed more activity in the long bursts. The results demonstrate that the type of information processing in the vMGB, which belongs to the ”primary” auditory system, is different from that in two other subdivisions of the MGB., E. Kvašňák, J. Popelář, J. Syka., and Obsahuje bibliografii