[Intracellular pH measurement in glioblastoma cells: the possibilities of phosphorus-31 MR spectroscopy]. / Izmerenie vnutrikletochnogo vodorodnogo pokazatelya glioblastom: vozmozhnosti fosfornoi magnitno-rezonansnoi spektroskopii.

OBJECTIVE: To analyze intracellular pH measurement with phosphorus-31 MR spectroscopy in glioblastoma cells and to compare these data with intracellular pH in healthy volunteers. MATERIAL AND METHODS: There were 10 patients aged 41 - 67 years with supratentorial glioblastomas. Intracellular pH in glioblastoma cells was compared with pH in healthy persons. RESULTS: We found a tendency to increased intracellular pH in glioblastoma cells in comparison with pH in intact brain tissue. CONCLUSION: Intracellular pH in brain tissue can be used as a potential marker of early abnormalities which could not be detected by conventional MRI. Moreover, these data may be valuable to estimate the efficacy of chemotherapy. The study was supported by Russian Science Foundation (grant No. 18-15-00337).

[Phosphorus (P) magnetic resonance spectroscopy for evaluation of brain tissue metabolism and measuring non-invasive pH. A study involving 23 volunteers. Part I]. / Fosfornaia (R) MR-spektroskopiia v otsenke énergeticheskogo metabolizma mozgovoi tkani i neinvazivnom izmerenii pH. Issledovanie 23 dobrovol'tsev. Chast' I.

Evaluation of brain metabolism is an important part in examination of brain lesions. Phosphorus magnetic resonance spectroscopy opens up great opportunities for studying the energy metabolism and allows noninvasive examination of metabolic processes occurring both in healthy and in pathologic brain tissue by obtaining a spectrum of phosphorus-containing metabolites involved in the turnover of cell membrane phospholipids. The technique presented in this paper was used to conduct 31P MR spectroscopy and to estimate the ratio between the peaks of the main metabolites and intracellular pH of the healthy brain tissue of 23 volunteers in the age group under 30 years old in clinical settings. Based on the recorded stable phosphorus spectra of metabolites of the healthy brain tissue, the value of intracellular pH (6.963±0.044) and the ratio of the main PME/PDE peaks (1.17±0.20) were calculated. The database was created to subsequently analyze the metabolic changes in brain tissue spectra in norm and in pathology, as well as the intracellular pH variations that have diagnostic and prognostic value.

[Evaluation of vascular reactivity to overcome limitations of neurovascular uncoupling in BOLD fMRI of malignant brain tumors]. / Otsenka vazoreaktivnosti dlia preodoleniia ogranichenii neirovaskuliarnogo razobshcheniia BOLD fMRT pri zlokachestvennykh opukholiakh golovnogo mozga.

The sensitivity of fMRI in identification of eloquent cortical centers in the case of large infiltrative growing tumors and pronounced peritumoral edema may be reduced or significantly limited in some cases. The main cause is an attenuated Blood-Oxygen-Level-Dependent response (BOLD) caused by pathological vascular reactivity and subsequent neurovascular uncoupling of fMRI. In our study, we attempted to overcome these limitations and increase the sensitivity of this technique in identification of eloquent cortical areas adjacent to brain tumors by using vasoreactivity features of a breath-holding test and including these data in the BOLD analysis. Local vasoreactivity using a breath-holding paradigm with the same block design of both motor and speech tests was determined in 5 healthy volunteers and 3 patients in the preoperative period (two patients with high grade gliomas and one patient with single metastasis). A coherence-based model was developed for analysis of BOLD fMRI, which took into account altered hemodynamics in peritumoral zones. Obtained coherence maps demonstrated clinically more significant activation zones that were not seen with standard methods of fMRI processing. Thus, neurovascular uncoupling that is known to affect the accuracy of the BOLD fMRI response adjacent to brain tumors may be partially overcome by including an independent measurement of vasoreactivity using a breath-holding test in the BOLD analysis.

[3D proton MR spectroscopy of the gray and white brain matter. A study of 15 volunteers]. / Protonnaia 3D MR-spektroskopiia serogo i belogo veshchestva golovnogo mozga. Issledovanie 15 dobrovol'tsev.

One of the important problems of modern diagnostics of brain diseases is detection of early lesions, which determines the choice of patient management and the disease outcome. The introduction of magnetic resonance imaging in practice has significantly improved the quality of diagnosis. Multivoxel proton magnetic resonance spectroscopy is an additional and clarifying technique enabling non-invasive examination of changes in brain metabolism in tumors as well as simultaneous acquisition of information on metabolism in surrounding tissues and in the intact brain matter. Along with single voxel MR spectroscopy (SV MRS) and 2D MRS (CSI Chemical Shift Imaging), 3D proton MRS (MRSI) has been increasingly used in clinical practice, which enables single-run acquisition of data on the metabolite composition for the entire volume of interest. OBJECTIVE: To assess the possibility of using multivoxel 3D proton MRS in healthy volunteers without organic brain pathology. MATERIAL AND METHODS: In this study, 15 volunteers without organic brain pathology were examined using the 3D 1H-MRS. CONCLUSION: 3D proton MRS has proven to be an effective technique in studying the brain metabolism. One short-term series of examinations provided information on intact brain metabolism at different anatomical levels, which enabled their comparison both in spectral data and in parametric maps of the major metabolite distribution.

A solid-phase fluorescent biosensor for the determination of phenolic compounds and peroxides in samples with complex matrices.

A solid-phase fluorescent biosensor for the determination of phenolic compounds (simple substituted phenols and catecholamines) and peroxides has been developed. The biosensor has a simple construction and the analytical signal is measured directly in a biosensitive layer {peroxidase-chitosan} on the sensor surface. This approach allowed analyzing samples with complex matrices (including water-insoluble samples and nontransparent solutions) without their preliminary pretreatment. Two novel fluorescent indicator reactions for the determination of the above-mentioned analytes in wide concentration ranges (from nmol l(-1) to mm l(-1)) which provided an analytical signal registration on a solid phase were proposed. The developed sensor was applied successfully for the analysis of urine, cosmetics, pharmaceuticals preparations, etc.

Properties and analytical applications of the self-assembled complex {peroxidase-chitosan}.

A novel promising approach to the improvement of analytical properties of horseradish peroxidase based on its inclusion into self-assembled structures of chitosan is discussed. It is shown that the reasonable choice of a polyelectrolyte, a detailed investigation of its interaction with the enzyme and the conditions of the {peroxidase-polyelectrolyte} complex formation allow for stabilizing the biocatalyst in aqueous and aqueous-organic media without a substantial loss in its activity and developing corresponding analytical procedures and biosensors. The latter provides highly selective determination of a number of organic compounds and sensitive determination of heavy metal ions that becomes possible due to the specific interactions of the analytes with the polymer matrix. Besides, the application of the proposed analytical systems and biosensors provides the expansion of the range of the compounds, and poorly water soluble and slowly oxidized substrates of peroxidase as well, which could be determined and real samples which could be analyzed by enzymatic methods. Analytical performance of the developed spectrophotometric indicator procedures and biosensors based on the self-assembled complex {peroxidase-chitosan} is demonstrated in the determination of metal ions (Hg(II), Cd(II), and Pb(II)), phenothiazines (promazine, chloropromazine, and trifluoroperazine), phenolic compounds (phenol, hydroquinone, catechol, pyrogallol, quercetin, rutin, and esculetin), organic peroxides (tert-butyl peroxide, 2-butanone peroxide, and benzoyl peroxide) in various samples, including water-insoluble matrices.

[CyberKnife stereotactic radiotherapy for mass lesions of the spinal cord and spine].

Introduction of a novel technology of stereotactic radiation treatment using linear accelerators, refining of systems for visualization and guidance provided rapid development of extracranial radiosurgery. Nowadays there is a possibility of precise stereotactic irradiation of lesions with different size and localization. One of the most actual and promising indications for radiosurgery are different primary and metastatic lesions and arteriovenous malformations of spinal cord and spine. Radiosurgery and hypofractionated radiotherapy with precise dose delivery during one or several sessions allow effective and safe treatment of neoplasms with any degree of radioresistance. This paper contains analysis of the first Russian experience of stereotactic radiation treatment of lesions of spinal cord and spine using robotized system CyberKnife (Accuray Inc., USA).

[Postoperative assessment of the efficiency of the radical removal of glioblastomas in the cerebral hemispheres]. / Posleoperatsionnaia otsenka radikal'nosti udaleniia glioblastom bol'shikh polusharii golovnogo mozga.

The paper analyzes the capacities of computed tomography (CT) and magnetic resonance imaging (MRI) in the postoperative period to evaluate the efficiency of surgical removal of the most malignant type of gliomas of the cerebral hemispheres. A total of 45 patients with different histological forms of cerebral hemispheral gliomas were examined, 37 of them with glioblastomas. Comparison of the results obtained by CT and MRI within the first 24 hours indicated that the latter was of greater informative value in all cases. At the same time only the use of a strict methodological approach to postoperatively estimating the remaining portions of glioblastomas makes it possible to apply these two methods as objective criteria for evaluating the efficiency of removal of a glioblastoma and hence the efficiency of subsequent therapeutic protocols. Contrast-enhanced MRI may be regarded as the method of choice in the primary assessment of patients with suspected recurrent glioblastoma.

[Complex MR-diagnosis of brain abscesses]. / Kompleksnaia MR-diagnostika abstsessov golovnogo mozga.

Early diagnosis of brain inflammatory lesion is a basic factor in choosing treatment policy. The paper investigates the use and informative value of diffuse-weighed magnetic resonance imaging in the differential diagnosis of brain abscesses and processes of another origin. It also considers the application of MR spectroscopy and perfusion MRI to obtain additional information on an inflammatory processes. A series of observations covered 10 patients with brain abscesses at different sites. Diffusion-weighed image (DWI) revealed a drastic increase in a MR signal from the central abscess portions (a pyonecrotic area), which is suggestive of decreased diffusion of water molecules. The measured diffusion ratios (MDRs) were significantly lower in the central abscess area (p < 0.005) than those in the capsule and white matter of the brain at all values of the diffuse factor b (500, 1000 sec/mm2); the capsule was better visualized at the DWI at b = 500 sec/mm2. In addition, MDRs were significantly different within the annular contrasting area of abscesses and glioblastomas, in the abscess/tissue capsule, and edema (p < 0.01). Proton spectroscopy of the central abscess area (pus) revealed succinate, acetate, alanine, peaks of lactate and amino acid. Perfusion MR study (bolus contrasting and estimation of the tissue parameters rCBV and MTT) has indicated that the central abscess in relation to the medulla is a decreased perfusion area; perfusion in the abscess capsule is close to that in the medulla in its characteristics, but medullary time in this area is shorter than that in brain tissues; perifocal edema is also characterized by hypoperfusion. The analysis of complex MRI study in patients with brain abscesses has demonstrated that diffuse-weighed MRI enhances diagnostic specificity, diagnoses the development of a pyonecrotic abscess center at early stages of capsule formation; MR spectroscopy is an additional method of differential diagnosis of brain abscess and processes of another nature whereas perfusion MRI provides additional information on medullary hemodynamic changes.

[Diffusion-weighted image in the study of brain tumors and peritumoral edema]. / Diffuzionno-vzveshennye izobrazheniia v issledovanii opukholei golovnogo mozga i peritumoral'nogo oteka.

The informative value of the technique of diffusion-weighted images (DWI) and diffusion maps was studied in diagnosing supratentorial tumors of the brain. Sixty four patients were examined. Among them there were 35 patients with glial brain neoplasms of varying malignancy [benign astrocytomas (asc) in 15 patients, anaplastic asc in 10, and glioblastomas in 10)], 15 patients with meningiomas, 5 with hydrocephalus, 9 with cerebral circulatory disorders. To obtain DWI, diffusion-weighted echo-planar impulse sequence was used. ADC was within (1.52 +/- 0.34) x 10(-3) mm2/sec for fibrillary astrocytomes. The anaplastic astrocytoma group showed variations in ADC values: ADC was higher in the contrasted part of the tumor than in the non-contrasted one and averaged (1.23 +/- 0.32) x 10(-3) mm2/sec. Glioblastomas were also noted for a higher variation in ADC that averaged (1.18 +/- 0.29) x 10(-3) mm2/sec. Meningiomas had a greater MR signal in response to DWI and low ADC values [(0.97 +/- 0.17) x 10(-3) mm2/sec]. Particular emphasis is laid on the study of different types of brain edema. ADC in the area of vasogenic (peritumoral), cytotactic (ischemic), and interstitial edema was (1.30 +/- 0.11) x 10(-3), (1.04 +/- 0.05) x 10(-3), and (1.91 +/- 0.1) x 10(-3) mm2/sec, respectively (p < 0.05) and sharply distinct in ADC maps.