Registry of Acute Myocardial Infarction. REGION-MI - Russian Registry of Acute Myocardial Infarction.

Aim      To study features of diagnosis and treatment of acute myocardial infarction (AMI) in Russian hospitals, results of the treatment, and early and late outcomes (6 and 12 months after AMI diagnosis); to evaluate the consistence of the treatment with clinical guidelines; and to evaluate patients' compliance with the treatment.Material and methods  The program was designed for 3 years, including 24 months for recruitment of patients to the study. The study will include 10, 000 patients hospitalized with a confirmed diagnosis (I21 according to ICD-10) of ST segment elevation acute myocardial infarction (MI) (STEMI) or non-ST segment elevation MI (NSTEMI) based on criteria of the European Society of Cardiology Guidelines on Forth Universal Definition of Myocardial Infarction (2018). The follow-up period was divided into three stages: observation during the stay in the hospital and at 6 and 12 months following inclusion into the registry. The primary endpoint included cardiac death, nonfatal MI during the hospitalization and after one-year follow-up. Secondary endpoints were 6-months and one-year incidence of repeated MI, heart failure, ischemic stroke, clinically significant hemorrhage, unscheduled revascularization after discharge from the hospital, and the proportion of patients who continue on statins, antiplatelet drugs, and drugs of other groups for 6 months and 1 year.Results The inclusion of patients into the registry started in 2020 and will continue for 24 months. By the time of the article publication (June, 2021), more than 2,000 patients will be included.Conclusion      REGION-MI (Russian rEGIstry Of acute myocardial iNfarction) is a multicenter, retrospective and prospective observational cohort study that excludes any interference with the clinical practice. Results of the registry will help to analyze a real picture of medical care provided to patients with myocardial infarction and to schedule ways to improve the situation.

Effects of new fluorinated analogues of GABA, pregabalin bioisosters, on the ambient level and exocytotic release of [3H]GABA from rat brain nerve terminals.

Recently, we have shown that new fluorinated analogues of γ-aminobutyric acid (GABA), bioisosters of pregabalin (ß-i-Bu-GABA), i.e. ß-polyfluoroalkyl-GABAs (FGABAs), with substituents: ß-CF3-ß-OH (1), ß-CF3 (2); ß-CF2CF2H (3), are able to increase the initial rate of [3H]GABA uptake by isolated rat brain nerve terminals (synaptosomes), and this effect is higher than that of pregabalin. So, synthesized FGABAs are structural but not functional analogues of GABA. Herein, we assessed the effects of synthesized FGABAs (100µM) on the ambient level and exocytotic release of [3H]GABA in nerve terminals and compared with those of pregabalin (100µM). It was shown that FGABAs 1-3 did not influence the ambient level of [3H]GABA in the synaptosomal preparations, and this parameter was also not altered by pregabalin. During blockage of GABA transporters GAT1 by specific inhibitor NO-711, FGABAs and pregabalin also did not change ambient [3H]GABA in synaptosomal preparations. Exocytotic release of [3H]GABA from synaptosomes decreased in the presence of FGABAs 1-3 and pregabalin, and the effects of FGABAs 1 &3 were more significant than those of FGABAs 2 and pregabalin. FGABAs 1-3/pregabalin-induced decrease in exocytotic release of [3H]GABA from synaptosomes was not a result of changes in the potential of the plasma membrane. Therefore, new synthesized FGABAs 1 &3 were able to decrease exocytotic release of [3H]GABA from nerve terminals more effectively in comparison to pregabalin. Absence of unspecific side effects of FGABAs 1 &3 on the membrane potential makes these compounds perspective for medical application.

Dynamic Gradient of Glutamate Across the Membrane: Glutamate/Aspartate-Induced Changes in the Ambient Level of L-[14C]glutamate and D-[3H]aspartate in Rat Brain Nerve Terminals.

Extracellular/intracellular L-[14C]glutamate exchange and conservativeness of the extracellular level of L-[14C]glutamate was analyzed in isolated rat brain nerve terminals. L-Glutamate-, DL-threo-ß-hydroxyaspartate (DL-THA)-, and D-aspartate-induced increase in the ambient level of L-[14C]glutamate or D-[3H]aspartate was evaluated comparatively. 100 µM "cold" nonradiolabeled L-glutamate, DL-THA, D-aspartate extruded a quarter of radioactivity from L-[14C]glutamate-preloaded synaptosomes for 6 min. The similar results were obtained with L-glutamate-evoked extracellular/intracellular redistribution of D-[3H]aspartate. Contribution of presynaptic glutamate receptors to an increase in the extracellular L-[14C]glutamate level was evaluated using receptor agonists NMDA, AMPA, and kainate (100 µM), and it consisted of less than 5 % of total accumulated label. The existence of the efficient extracellular/intracellular glutamate exchange, and so dynamic glutamate gradient across the plasma membrane of nerve terminals was demonstrated. A two-substrate kinetic algorithm that included transporter reversal was considered. The extracellular level of L-[14C]glutamate and D-[3H]aspartate in nerve terminals depended on the amount of exogenous substrates of glutamate transporter available. Taking into account that L-glutamate, DL-THA, and D-aspartate are the substrates of glutamate transporters, and also the similarity in their effectiveness in the establishment of new extracellular level of the neurotransmitters, the central role of glutamate transporters in permanent glutamate turnover in nerve terminals was demonstrated.

[Primary multiple malignant lung tumors. References and a clinical observation].

The problem of primary multiple tumors is relevant to current clinical oncology because of increasing of number of patients with multiple malignant tumors and unsolved issues of treatment. Primary multiple malignant lung tumors is a common oncological situation requires an individualized, differentiated approach to treatment. The results of treatment are associated with the prevalence of the process, stages of tumor development, spare capacity of patients. There is presented clinical example of a patient with metachronous primary multiple malignant tumors of one lung.

Synthesis of new fluorinated analogs of GABA, Pregabalin bioisosteres, and their effects on [(3)H]GABA uptake by rat brain nerve terminals.

Fluorinated analogs of natural substances take an essential place in the design of new biologically active compounds. New fluorinated analogs of γ-aminobutyric acid, that is, ß-polyfluoroalkyl-GABAs (FGABAs), were synthesized with substituents: ß-CF3-ß-OH (1), ß-CF3 (2); ß-CF2CF2H (3). FGABAs are bioisosteres of Pregabalin (Lyrica®, Pfizer's blockbuster drug, ß-i-Bu-GABA), and have lipophilicity close to this medicine. The effects of synthesized FGABAs on [(3)H]GABA uptake by isolated rat brain nerve terminals (synaptosomes) were assessed and compared with those of Pregabalin. FGABAs 1-3 (100µM) did not influence the initial velocity of [(3)H]GABA uptake when applied acutely, whereas an increase in this parameter was found after preliminary incubation of FGABAs with synaptosomes. Pregabalin after preliminary incubation with synaptosomes caused unidirectional changes in the initial velocity of [(3)H]GABA uptake. Using specific inhibitors of GAT1 and GAT3, NO-711 and SNAP5114, respectively, the ability of FGABAs 1-3 to influence non-GAT1 and non-GAT3 uptake activity of nerve terminals was analyzed, but no specificity was found. Therefore, new synthesized FGABAs are structural but not functional analogs of GABA (because they did not inhibit synaptosomal [(3)H]GABA uptake). Moreover, FGABAs are able to increase the initial velocity of [(3)H]GABA uptake by synaptosomes, and this effect is higher than that of Pregabalin.

Excitotoxic potential of exogenous ferritin and apoferritin: changes in ambient level of glutamate and synaptic vesicle acidification in brain nerve terminals.

Ferritin, an iron storage protein, is present in the serum and cerebrospinal fluid, has receptors on the cell surface, able to penetrate the brain-blood barrier, can be secreted from the cells, and leaks from destroyed cell in insult and brain trauma. The effect of exogenous ferritin on the key characteristic of glutamatergic neurotransmission was assessed in rat brain nerve terminals (synaptosomes). Exogenous ferritin (80 µg/ml, iron content 0.7%) significantly increased the ambient level of L-[(14)C]glutamate (0.200±0.015 versus 0.368±0.016 nmol/mg of protein) and endogenous glutamate (fluorimetric glutamate dehydrogenase assay) in the nerve terminals. This increase was not a result of augmentation of tonic release because the velocity of tonic release of L-[(14)C]glutamate was not changed significantly in ferritin-treated synaptosomes as compared to the control. Ferritin caused a decrease in synaptic vesicle acidification that was shown using fluorescent dye acridine orange. Iron-dependence of the effects of ferritin was analyzed with apoferritin (0.0025% residual iron). Apoferritin weakly affected the proton electrochemical gradient of synaptic vesicles but increased the ambient level and decreased the initial velocity of uptake of L-[(14)C]glutamate by synaptosomes, nevertheless these effects were ~30% lesser than those caused by ferritin. Exogenous ferritin can provoke the development of excitotoxicity increasing the ambient level of glutamate and lowering synaptic vesicle acidification and glutamate uptake in the nerve terminals, however these effects are not completely iron-dependent. Thus, in the CNS exogenous ferritin can act as a modulator of glutamate homeostasis in iron-dependent and iron-independent manner.

[The role of stereotactic radiotherapy in treatment of patients with metastatic lesion of lungs].

Since February 2012, in order to increase the effectiveness of treatment and quality of life of patients with disseminated disease, there was developed and implemented a method of stereotactic radiotherapy for metastatic lesion of lungs by tumors of different histological types. 20 patients were treated by stereotactic radiotherapy ROD 7 Gy in five sessions during 5 days. There were evaluated results of treatment and prospects of this method.

[Results of complex treatment of patients with squamous cell carcinoma of the anal canal using advanced radiotherapy technologies].

During recent decades radiotherapy is the basis, on which it is built a medical complex that is the first-line treatment of patients with squamous cell carcinoma of the anal canal. An increase of overall and disease-free survival and quality of life of patients with squamous cell carcinoma of the anal canal at the present stage of development of a comprehensive medical treatment is largely due to the improvement of technical equipment of radiotherapy departments of oncology clinics. The use of modem linear electron accelerators and systems of computer dosimetric planning to create a 3D program of isodose distribution, diagnostic devices (computed tomography and magnetic resonance imaging) as well as a number of other conditions permit accurate summarizing of proposed dose, reducing of absorbed dose to critical structures, diminishing unplanned interruptions in chemoradiotherapy course by means of modern technologies of conformal radiotherapy (3D CRT, IMRT, VMAT). The paper presents the preliminary results of a comprehensive medical treatment of 14 patients with squamous cell carcinoma of the anal canal.

[Rubella virus genetic determinant of attenuation].

Vaccination is the most effective and available way to prevent Rubella. Presently, 9 vaccine strains were registered. Nevertheless, the molecular mechanisms of the attenuation were poorly elucidated for the rubella virus. However, the study of these mechanisms identifying genotypic and phenotypic markers of attenuation, which together with sequence analysis could be used for the genetic stability control of vaccine strains, is still of current interest. Common trends of genetic changes in the process of adaptation to cold were found due to comparison of nucleic acid and amino acid sequences of the Russian strain C-77 with corresponding positions of the known rubella virus strains and its wild type progenitors, if available.

Extracellular membrane vesicles derived from Komagataeibacter oboediens exposed on the International Space Station fuse with artificial eukaryotic membranes in contrast to vesicles of reference bacterium.

Membranous Extracellular Vesicles (EVs) of Gram-negative bacteria are a secretion and delivery system that can disseminate bacterial products and interact with hosts and the environment. EVs of nonpathogenic bacteria deliver their contents by endocytosis into eukaryotic cells, however, no evidence exists for a fusion delivery mechanism. Here, we describe the fusion of exposed to space/Mars-like stressors simulated on the International Space Station vesicles (E-EVs) from Komagataeibacter oboediens to different types of model planar membranes in comparison with the EVs of the ground-based reference strain. The most reliable fusion was achieved with PC:PE:ergosterol or sterol-free PC:PE bilayers. The relative permeability ratio (PK+/PCl-) estimated from the shift of zero current potential according to Goldman-Hodgkin-Katz equation consisted of 4.17 ± 0.48, which coincides with preferential cation selectivity of the EV endogenous channels. The increase in membrane potential from 50 mV to 100 mV induced the fusion of E-EVs with all tested lipid compositions. The fusion of model exosomes with planar bilayer lipid membranes was confirmed by separate step-like increases in its conductance. In contrast, the ground-based reference K. oboediens EVs never induced the fusion event. In our study, we show membrane lipidome perturbations and increased protein aggregation occurred in the exposed samples in the harsh environment when outer membranes of K. oboediens acquired the capability of both homo- and heterotypic fusion possibly by altered membrane fluidity and the pore-forming capability.

Neuroprotection by lowering cholesterol: a decrease in membrane cholesterol content reduces transporter-mediated glutamate release from brain nerve terminals.

BACKGROUND: In our earlier work, a reduction of cholesterol content increased the extracellular glutamate level in rat brain nerve terminals (synaptosomes) that was a result of the lack of transporter-mediated glutamate uptake. The aim of this study was to assess transporter-mediated release of glutamate from cholesterol-deficient synaptosomes. In stroke, cerebral hypoxia/ischemia, and traumatic brain injury, the development of neurotoxicity is provoked by enhanced extracellular glutamate, which is released from nerve cells mainly by glutamate transporter reversal - a distinctive feature of these pathological states. METHODS: Laser scanning confocal microscopy, spectrofluorimetry, radiolabeled assay, and glutamate dehydrogenase assay. RESULTS: Cholesterol acceptor methyl-ß-cyclodextrin (15mM) reduced the cholesterol content in the synaptosomes by one quarter. Transporter-mediated glutamate release from synaptosomes: 1) stimulated by depolarization of the plasma membrane; 2) by means of heteroexchange with competitive transportable inhibitor of glutamate transporters dl-threo-ß-hydroxyaspartate; 3) in low [Na(+)] medium; and 4) during dissipation of the proton gradient of synaptic vesicles by the protonophore cyanide-p-trifluoromethoxyphenyl-hydrazon (FCCP); was decreased under conditions of cholesterol deficiency by ~24, 28, 40, and 17%, respectively. CONCLUSIONS: A decrease in the level of membrane cholesterol attenuated transporter-mediated glutamate release from nerve terminals. Therefore, lowering cholesterol may be used in neuroprotection in stroke, ischemia, and traumatic brain injury which are associated with an increase in glutamate uptake reversal. This data may explain the neuroprotective effects of statins in these pathological states and provide one of the mechanisms of their neuroprotective action. However, beside these disorders, lowering cholesterol may cause harmful consequences by decreasing glutamate uptake in nerve terminals.

[Monitoring of enterovirus circulation in Irkutsk region].

AIM: Monitoring of circulation of enteroviruses (EVI) in Irkutsk Region and study of regional specter of circulating enteroviruses. MATERIALS AND METHODS: 1419 samples from patients with suspected EVI, contact in foci ofenterovirus infection, acute intestine infections and 964 samples of sewage water were studied in total. In 2011 isolation of viral agents from 97 samples positive on enterovirus by RT-PCR from patients with preliminary EVI diagnosis and 5 samples of sewage water of Irkutsk city was carried out. Transplantable line of human rhabdomyosarcoma RD cell culture was used for isolation of enteroviruses. Infection of cells and 2 serial passages of the studied material were carried out. The isolates were typed in neutralization reaction (NR) with a set of 32 diagnostic type-specific immune sera against viral poliomyelitis I-III; Coxsackie B1-6; Coxsackie A2, A4, A7, A9, A10; ECHO 68 - 71; ECHO 2, 4, 7, 8, 9, 12, 16, 20, 25, 26, 27, 29, 31, 33. RESULTS: In 2011 circulation of enterovirus serotypes that were previously absent on the territory of the region was established: ECHO 68, ECHO 70, ECHO 71. These strains were isolated from patients, circulation of ECHO 70 serotype was established also in samples of sewage water. The analysis of enterovirus landscape carried out showed the possibility of complication of epidemic situation on the territory of the region due to change of serovariants of causative agents of non-polioenterovirus infections and detection ofepidemically significant enteroviruses - ECHO 68, 70 and 71 serotypes. CONCLUSION: Determination of specter ofenterovirus serotypes, detection of serotypes that had not previously circulated in Irkutsk Region allows to prognose epidemic situation on morbidity of enterovirus infections and timely develop and make decisions for ensuring epidemiologic welfare of the population.

[Studying of molecular mechanisms of rubella virus attenuation evidence from Russian strain C-77].

Live attenuated rubella vaccine is used for vaccination. Temperature-sensitive (ts) phenotype was proved for almost all rubella vaccine strains, and the acquisition of the ts phenotype during cold adaptation was strongly correlated with the attenuation of the wild-type viruses. Nevertheless, the molecular mechanisms of the attenuation have been insufficiently understood for rubella virus. Study ofthese mechanisms, identifying genotypic markers of attenuation, which together with the sequence analyses could be used for genetic stability control of vaccine strains, is still of current interest. In this work, we determined nearly complete genome sequences of attenuated (ca) and the wildtype progenitor (wt) of the rubella virus strain C-77 isolated in Russia. Possible genetic determinants of attenuation were detected. Thus, 13 nucleotide differences leading to 6 amino acid substitutions were found. Four amino acid substitutions were found to be almost unique. Special consideration should be given to Tyr1042Cys substitution in the protease domain of C-77 strain, because it most probably plays the crucial role in acquisition of ts-phenotype.

[Polytypic strains in the genofund of tick-borne encephalitis virus].

Eighteen polytypic tick-borne encephalitis virus (TBEV) strains containing the fragments of E and NS1 protein genes of Siberian and Far Eastern, occasionally Siberian and European subtypes were isolated in the European and Asian parts of the tick-borne encephalitis (TBE) area. They were identified using real-time polymerase chain reaction, hybridization-fluorescence detection with genotype-specific probes, restriction fragment length polymorphism analysis, and E protein sequencing. The polytypic strains were isolated from individual Ixodes persulcatus ticks, their pools, from the blood of patients and the brain of dead patients. The isolation rates of the polytypic strains in the sympathry area of different TBEV subtypes ranged from 4.4% (the Irkutsk Region) to 15.1% (the Yaroslavl Region). In addition to 2 polytypic strains, a strain similar to the TBEV 886-84 strain was isolated. The TBEV subtypes entering into the composition of the polytypic strains show nongenetic interactions, such as neutral replication or competition. The polytypic strains are stable during passages in the cultured pig embryo kidney epithelial cells and on cloning. Mouse brain passage promotes dissociation of polytypic strains. The conditions for the formation of polytypic strains and their role in the etiology of TBE are discussed.

[M-29 human diploid cells line--a substrate for the production of antiviral vaccines].

AIM: Study of morphologic and karyologic characteristics of 5 russian human diploid cell lines (HDC). MATERIALS AND METHODS: 5 HDC lines and HDC strain MRC-5 were studied; RK-13 and Vero continuous cell lines were used; viruses: rubella (RA27/3), measles (L-16), epidemic parotitis (L-3). Cytogenetic analysis of HDC was performed by using DAPI differential staining method. RESULTS: M-29 line has characteristics that are similar to those of MRC-5 diploid cell strain. M-29 cell culture is not contaminated with foreign viruses, mycoplasmata, does not have oncogenic potency. CONCLUSION: M-29 line has high virus-productive properties for accumulation of measles, rubella and epidemic parotitis vaccine viruses and may be recommended as a substrate for the production of antiviral vaccines.

A new insight into mechanisms of interferon alpha neurotoxicity: Expression of GRIN3A subunit of NMDA receptors and NMDA-evoked exocytosis.

Neurological and psychiatric side effects accompany the high-dose interferon-alpha (IFNA) therapy. The primary genes responsible for these complications are mostly unknown. Our genome-wide search in mouse and rat genomes for the conservative genes containing IFN-stimulated response elements (ISRE) in their promoters revealed a new potential target gene of IFNA, Grin3α, which encodes the 3A subunit of NMDA receptor. This study aimed to explore the impact of IFNA on the expression of Grin3α and Ifnα genes and neurotransmitters endo/exocytosis in the mouse brain. We administered recombinant human IFN-alpha 2b (rhIFN-α2b) intracranially, and 24 h later, we isolated six brain regions and used the samples for RT-qPCR and western blot analysis. Synaptosomes were isolated from the cortex to analyze endo/exocytosis with acridine orange and L-[14C]glutamate. IFNA induced an increase in Grin3α mRNA and GRIN3A protein, but a decrease in Ifnα mRNA and protein. IFNA did not affect the accumulation and distribution of L-[14C]glutamate and acridine orange between synaptosomes and the extra-synaptosomal space. It caused the more significant acridine orange release activated by NMDA or glutamate than from control mice's synaptosomes. In response to IFNA, the newly discovered association between elevated Grin3α expression and NMDA- and glutamate-evoked neurotransmitters release from synaptosomes implies a new molecular mechanism of IFNA neurotoxicity.

[Quick test for measurement of rubella virus titer in virus-containing fluid using RT-PCR].

AIM: To develop method of rubella virus titer measurement in virus-containing fluid using real-time PCR (RT-PCR) with fluorescent detection. MATERIALS AND METHODS: Measurement of infectious titer of rubella virus (Wistar RA 27/3 strain) cultivated on Vero cells was performed simultaneously by RT-PCR and cytopathic effect assay (CEA) on PK-13 cell culture and then results obtained by each method were compared. RESULTS: Time interval after inoculation, in which difference between virus titer measured by both methods did not exceed 0.3 1gTCD50/ml (value acceptable by WHO), was 2 - 7 days. Pearson correlation coefficient between two values for the mentioned interval was close to 1, which point to good agreement of results. In control sample--international vaccine standard of rubella virus--difference in virus titer determined by RT-PCR and CEA was within 0.2 1gTCD50/ml that lower than value acceptable by WHO. CONCLUSION: Method for measurement of rubella virus titer in virus-containing fluid using RT-PCR was developed, which characterized by high specificity, sensitivity, standard performing, shorter time needed for procedure compared with classic methods and, at the same time, high correlation of its results with results obtained by the latter methods during defined time interval.

Dual benefit of combined neuroprotection: Cholesterol depletion restores membrane microviscosity but not lipid order and enhances neuroprotective action of hypothermia in rat cortex nerve terminals.

Here, both neuroprotectants, i.e. cholesterol depletion of the plasma membrane of rat brain nerve terminals (synaptosomes) using methyl-ß-cyclodextrin (MßCD) and deep/propound hypothermia, were analyzed during their combined administration and regarding additive neuroprotective effect. The extracellular synaptosomal level of L-[14C]glutamate significantly increased after treatment with MßCD in both deep and profound hypothermia. Cholesterol depletion gradually enhanced inhibiting effect of deep and profound hypothermia on glutamate uptake and "excitotoxic" transporter-mediated release of L-[14C]glutamate. A decrease in L-[14C]glutamate release via heteroexchange from nerve terminals in deep and profound hypothermia was enhanced by cholesterol deficiency that confirmed previous result. Fluorometric studies with probes NR12S and DCVJ revealed oppositely directed effects of cholesterol depletion and hypothermia on synaptosomal membrane lipid order and microviscosity showing that cholesterol depletion can normalise up to the control hypothermia-induced increase in microviscosity, but not the lipid order of the synaptosomal membrane. Dynamics of changes in exocytosis in nerve terminals, which involved membrane fusion stage, was different from transporter-dependent ones. Hypothermia did not augment effects of cholesterol depletion on exocytotic L-[14C]glutamate release and lowering cholesterol enhanced the impact of deep, but not profound hypothermia on this parameter. Therefore, dual benefit of combined neuroprotection was demonstrated. Cholesterol depletion enhanced neuroprotective effects of hypothermia intensifying inhibition of "excitotoxic" transporter-mediated glutamate release and can normalise a hypothermia-induced increase in microviscosity of the synaptosomal membrane. This feature is prospective in mitigation of side effects of therapeutic hypothermia, and also for brain conservation preserving normal physical and chemical properties of the cellular membranes.

Levetiracetam-mediated improvement of decreased NMDA-induced glutamate release from nerve terminals during hypothermia.

A combination of a beneficial neuroprotectant, hypothermia, with targeted medication is a perspective therapeutic approach. Here, we analyzed both non-specific (deep and profound hypothermia, 27 °C and 17 °C, respectively) and targeted (anticonvulsant drug levetiracetam) modulation of l-[14C]glutamate release induced by activation of presynaptic NMDA, AMPA, and kainate receptors in rat brain nerve terminals (synaptosomes). Gradual dynamics of hypothermia-mediated decrease in synaptosomal l-[14C]glutamate release evoked by the receptor agonists NMDA-, AMPA-, and kainate (250 µM) has been demonstrated that can be of value for the justification of optimal temperature regimes in therapeutic hypothermia. 250 µM NMDA-induced l-[14C]glutamate release from nerve terminals was higher in the presence of levetiracetam (100 µM) as compared to that without the drug. Despite levetiracetam effects decreased in hypothermia, combined application of hypothermia and levetiracetam resulted in higher NMDA-induced l-[14C]glutamate release from nerve terminals as compared to that without the drug. These effects were not revealed for synaptosomal AMPA- and kainate-induced l-[14C]glutamate release in the presence of levetiracetam at the similar concentration. Therefore, levetiracetam administration significantly mitigated a hypothermia-induced decrease in NMDA receptor response at the presynaptic level and can be used for the targeted neurocorrection to reduce side effects of hypothermia in cardiac surgery. However, levetiracetam-mediated improvement of NMDA receptor response is not applicable in stroke, brain trauma and neonatal asphyxia therapies, where the main neuroprotective action of hypothermia is associated with prevention of damaging consequence of pre-existing acute glutamate exitotoxicity.

An amperometric glutamate biosensor for monitoring glutamate release from brain nerve terminals and in blood plasma.

An excess of the excitatory neurotransmitter, glutamate, in the synaptic cleft during hypoxia/ischemia provokes development of neurotoxicity and originates from the reversal of Na+-dependent glutamate transporters located in the plasma membrane of presynaptic brain nerve terminals. Here, we have optimized an electrochemical glutamate biosensor using glutamate oxidase and developed a biosensor-based methodological approach for analysis of rates of tonic, exocytotic and transporter-mediated glutamate release from isolated rat brain nerve terminals (synaptosomes). Changes in the extracellular glutamate concentrations from 11.5 ±â€¯0.9 to 11.7 ±â€¯0.9 µΜ for 6 min reflected a low tonic release of endogenous glutamate from nerve terminals. Depolarization-induced exocytotic release of endogenous glutamate was equal to 7.5 ±â€¯1.0 µΜ and transporter reversal was 8.0 ±â€¯1.0 µΜ for 6 min. The biosensor data correlated well with the results obtained using radiolabelled L-[14C]glutamate, spectrofluorimetric glutamate dehydrogenase and amino acid analyzer assays. The blood plasma glutamate concentration was also tested, and reliability of the biosensor measurements was confirmed by glutamate dehydrogenase assay. Therefore, the biosensor-based approach for accurate monitoring rates of tonic, exocytotic and transporter-mediated release of glutamate in nerve terminals was developed and its adequacy was confirmed by independent analytical methods. The biosensor measurements provided precise data on changes in the concentrations of endogenous glutamate in nerve terminals in response to stimulation. We consider that the glutamate biosensor-based approach can be applied in clinics for neuromonitoring glutamate-related parameters in brain samples, liquids and blood plasma in stroke, brain trauma, therapeutic hypothermia treatment, etc., and also in laboratory work to record glutamate release and uptake kinetics in nerve terminals.