A Gridded Electron Gun for a Sheet Beam Klystron

This paper describes the development of an electron gun for a sheet beam klystron. Initially intended for accelerator applications, the gun can operate at a higher perveance than one with a cylindrically symmetric beam. Results of 2D and 3D simulations are discussed

Numerical Simulation of the Medical Linear Accelerator Electron Beams Absorption by ABS-Plastic doped with Metal

In this paper the numerical simulation results of the dose spatial distribution of the medical electron beams in ABS-plastic doped with different concentrations of lead and zinc are shown. The dependences of the test material density on the lead and zinc mass concentrations are illustrated. The depth dose distributions of the medical electron beams in the modified ABS-plastic for three energies 6 MeV, 12 MeV and 20 MeV are tested. The electron beam shapes in the transverse plane in ABS-plastic doped with different concentrations of lead and zinc are presented

Approaches to Pharmaceutical Analysis of Modern Peptide and Oligonucleotide Products as Illustrated by a Small Interfering RNA-Based Novel Therapeutic for the Treatment of Bronchial Asthma

Methods used to control the quality of peptide products depend on the level of development of analytical and bioorganic chemistry, and the level of instrumentation. Peptide identification is a difficult task and largely depends on the complexity of its structure. There does not exist a comprehensive and simple test, except for NMR, which, however, is rather expensive and time-consuming and involves complex data interpretations. Moreover, it does not allow for unambiguous determination of the peptide purity and formula (amino acid composition, sequence, chirality of amino acid residues). For this reason, a combination of methods is often used, including amino acid analysis, TLC/HPLC and mass spectrometry, and, less frequently, sequencing. Current international practice of peptide analysis is to use HPLC in combination with mass spectrometric, mainly tandem (HPLC-MS/MS), detection. According to literature sources the amino acid sequence of linear peptides can be analysed using various enzymes and subsequent identification of proteolysis products by mass spectrometry. This article presents approaches to the development of test methods for analysis of purity and identification testing of a small interfering RNA-based novel medicinal product, which will help standardise and control the quality of the production process

Comparative study of perindopril and perindopril metabolite pharmacokinetics using the HPLC/MS method

Perindopril is a prodrug which is converted to an active metabolite perindoprilat in the human organism. The present study led to the development of a fast and easily reproducible procedure for simultaneous detection of perinoprilat and its metabolite in plasma using HPLC with mass-spectrometric detector (LC-MS). Detection of the target substance was performed using atmospheric pressure electrospray ionization (API-ES) techniques in negative polarity in two modes: SIM1, ion, m/z=368,10 for perindopril and SIM2, ion, m/z=339,30 for perindoprilat. Retention time of perindopril was about 2,4 min, for perindoprilat - about 1,4 min. Sample processing was performed using solid-phase extraction. The method’s limit of quantification was equal to 1 ng/ml for perindopril and 1 ng/ml for perindoprilat. The developed procedure was used to analyse pharmacokinetics and bioequivalence of medicines containing 8 mg of perindopril. Values of all calculated pharmacokinetic parameters had no statistically meaningful differences. Confidence intervals obtained fall within bioequivalence criterion (80-125% for AUC and 75-133% for Сmax и Cmax/AUC). The medicines under analysis were found to be bioequivalent

Analysis of Pharmacokinetic Parameters of Acetylsalicylic Acid for Prediction of Potential Nephrotoxic Effects

Nonsteroidal anti-inflammatory drugs, including acetylsalicylic acid, can have a dose-dependent nephrotoxic effect. The study of the pharmacokinetics of acetylsalicylic acid products will contribute to timely detection and correction of side effects caused by this medicinal product.The aim of the study was to evaluate potential nephrotoxic effects following a single oral administration of 75 mg of acetylsalicylic acid, based on the analysis of the pharmacokinetic parameters.Materials and methods: the study involved 24 healthy volunteers who received 75 mg of acetylsalicylic acid (tablets) once orally. The measurement of the active metabolite of acetylsalicylic acid—salicylic acid—in blood plasma was performed by HPLC/MS using an Agilent 1200 liquid chromatography system coupled to an Agilent 6140 tandem mass spectrometer. Agilent Eclipse XDB-C18 column (4.6 mm×150 mm; 5.0 μm) was used for chromatographic separation. The test procedure used in the study was validated. The results obtained were used to calculate the pharmacokinetic parameters: Cmax (maximum concentration), Tmax (time to maximum concentration), T1/2 (half-life of the drug), AUC0-t (area under the pharmacokinetic curve from 0 to the last time point of the curve), AUC0-∞ (total area under the pharmacokinetic curve from 0 to ∞), MRT (mean residence time of the drug in the blood), Kel (elimination rate constant), Cl/F (total clearance), Vd/F (apparent volume of distribution). The Statistics (22.0.0.0) software was used for statistical processing of the results.Results: T1/2 of salicylic acid in blood plasma was determined to be 1.6 ± 0.5 h, Cmax was 4523.0 ± 725.0 ng/mL, and Tmax was 0.98 ± 0.4 h. AUC0–t was equal to 16183.0 ± 3823.0 ng×h/m, Vd/F was 12.0 ± 3.1 L/kg, and MRT was 2.9 ± 0.6 h.Conclusions: the analysis of the pharmacokinetic parameters demonstrated a high absorption rate, intensive distribution, and moderate elimination rate of salicylic acid (the main metabolite of acetylsalicylic acid), indicating a low risk of nephrotoxic effects associated with the studied dose of the drug

Comparative Dissolution Kinetics of Several Multisource Thioctic Acid Products

The relationship between dissolution and bioavailability is an example of the interdependency between the quality of a medicinal product and its safety and efficacy. The uniqueness of thioctic acid is that it can exist in an oxidised and a reduced form, showing lipophilic (lipoic acid) and hydrophilic (dihydrolipoic acid) properties. Bioavailability studies of thioctic acid are necessary to evaluate the expected therapeutic effect and mitigate side effects of the medicinal product.The aim of the study was to carry out equivalence dissolution testing to compare the release of thioctic acid from medicinal products produced by several manufacturers.Materials and methods: the study used a reference medicinal product and three multisource medicinal products by different manufacturers; more specifically, film-coated tablets containing 600 mg of thioctic acid. The experiment was carried out in dissolution media at pH of 6.8±0.05 and 1.2±0.05. Statistical analysis was performed by calculating the average amounts of the substance dissolved, the standard deviation (SD), and the relative standard deviation (RSD, %) using Microsoft Office Excel 2007.Results: The authors chose the testing conditions (dissolution media pH values of 6.8±0.05 and 1.2±0.05) taking into account the nature and characteristics of thioctic acid. The comparison of thioctic acid release profiles based on the calculation of the similarity factor (f2) showed that the dissolution profiles of multisource medicinal products 2 and 3 at pH 6.8 were equivalent to that of the reference medicinal product (more than 85% of the active pharmaceutical ingredient released within 15 minutes) and the dissolution profile of multisource medicinal product 1 was not equivalent to it (with f2 of 28).Conclusions: the established differences in the rate and degree of active ingredient release from the studied medicinal products may indicate possible differences in their pharmacological effectiveness in vivo

Retargeted adenoviruses for radiation-guided gene delivery

The combination of radiation with radiosensitizing gene delivery or oncolytic viruses promises to provide an advantage that could improve the therapeutic results for glioblastoma. X-rays can induce significant molecular changes in cancer cells. We isolated the GIRLRG peptide that binds to radiation-inducible 78 kDa glucose-regulated protein (GRP78), which is overexpressed on the plasma membranes of irradiated cancer cells and tumor-associated microvascular endothelial cells. The goal of our study was to improve tumor-specific adenovirus-mediated gene delivery by selectively targeting the adenovirus binding to this radiation-inducible protein. We employed an adenoviral fiber replacement approach to conduct a study of the targeting utility of GRP78-binding peptide. We have developed fiber-modified adenoviruses encoding the GRP78-binding peptide inserted into the fiber-fibritin. We have evaluated the reporter gene expression of fiber-modified adenoviruses in vitro using a panel of glioma cells and a human D54MG tumor xenograft model. The obtained results demonstrated that employment of the GRP78-binding peptide resulted in increased gene expression in irradiated tumors following infection with fiber-modified adenoviruses, compared with untreated tumor cells. These studies demonstrate the feasibility of adenoviral retargeting using the GRP78-binding peptide that selectively recognizes tumor cells responding to radiation treatment

Значение редокс-статуса коэнзима Q10 как биомаркера окислительного стресса

The article examines the role of ubiquinone as a redox molecule whose functions consist in electron transport in the mitochondrial respiratory chain and regeneration of endogenous antioxidants. Changes in electron redox pathways cause uncontrolled release of reactive oxygen species, which leads to oxidative stress and development of pathologies. The objective of the study was to determine the content of coenzyme Q10 and its redox status in the human body as a biomarker of oxidative stress in various pathologies. This was achieved by assessing and consolidating data on changes in concentrations of the oxidized, reduced ubiquinone forms and total ubiquinone in various pathologies. Total serum ubiquinone was reduced in patients with chronic heart failure (0.68 μmol/L) compared with the control group (0.97 μmol/L). The redox status, expressed as the [ubiquinol]/ [ubiquinone] concentration ratio, decreased in patients with coronary heart disease (0.49 ± 0.34), diabetes (0.26 ± 0.16) compared with the healthy subjects (1.23–1.41). A negative correlation with malonic dialdehyde was observed. The authors analysed the possibility of assessing the efficacy of statin therapy by plasma ubiquinone concentration in patients. Patients with hyperlipidemia who received statins showed a statistically significant reduction in ubiquinol concentration after taking the drug (from 0.81 to 0.46 μg/mL) and the [ubiquinone]/[total ubiquinone] ratio (from 11 to 10 %), which confirms the potential mechanism of statinassociated muscle injury development. Thus, coenzyme Q10 redox status, as well as the concentrations of oxidized, reduced and total ubiquinone can be effective biomarkers of oxidative stress in cardiovascular diseases, diabetes, as well as an important indicator in evaluating the efficacy of hyperlipidemia treatment.Рассмотрена роль убихинона как редокс-молекулы, функциями которой являются перенос электронов в дыхательной цепи митохондрии и регенерация эндогенных антиоксидантов. Изменение редокс-путей электронов вызывает неконтролируемую выработку активных форм кислорода, что приводит к окислительному стрессу и развитию патологий. Цель работы — выявление содержания коэнзима Q10 и значения его редокс-статуса в организме как биомаркера окислительного стресса при различных патологиях, для чего были оценены и обобщены данные о динамике концентраций окисленной, восстановленной формы и общего убихинона при различных патологиях. Содержание общего убихинона в сыворотке крови пациентов с хронической сердечной недостаточностью было снижено (0,68 мкмоль/л) по сравнению с контрольной группой (0,97 мкмоль/л). Редокс-статус, выраженный как отношение концентрации [убихинол]/[убихинон], снижался у пациентов с ишемической болезнью сердца (0,49 ± 0,34), диабетом (0,26 ± 0,16) по сравнению со здоровыми лицами (1,23–1,41). При этом наблюдалась отрицательная корреляция с малоновым диальдегидом. Проведен анализ возможности оценки эффективности статинотерапии по содержанию убихинона в плазме крови пациентов. У пациентов с гиперлипидемией, получавших статины, были достоверно снижены концентрация убихинола после приема препарата (с 0,81 до 0,46 мкг/мл) и соотношение [убихинон]/[общий убихинон] (с 11 до 10 %), что подтверждает потенциальный механизм возникновения статин-ассоциированных поражений мышц. Таким образом, редокс-статус коэнзима Q10, а также концентрация окисленного, восстановленного и общего убихинона могут быть эффективными биомаркерами окислительного стресса при сердечно-сосудистых заболеваниях, диабете, а также важным показателем при оценке эффективности лечения гиперлипидемии

Подход к количественному определению эндогенных веществ в биожидкостях хроматографическим методом с использованием математического аппарата

Relevance of the study: The quantification of endogenous substances is an important task in experimental and clinical pharmacology. In the case of working with endogenous compounds, certain difficulties arise. The main one is the impossibility of obtaining the same biomatrix without endogenous compounds for use as standard solutions in the construction of calibration curves. Purpose: The aim of our study was to develop a mathematical methodology for calculating the concentration of endogenous compounds in biological objects measured by chromatography, which allows us to obtain a statistically reliable interval estimation of the concentration of endogenous compounds. Materials and methods: To implement the computational part of the proposed algorithm, the Mathcad engineering calculation program version 15.0 from PTC (Parametric Technology Corporation) is used, which operates under the family of Windows operating systems (XP, 7, Vista, 8). Main results: A mathematical methodology has been developed for calculating the concentration of endogenous compounds in biological objects measured by chromatography, which allows one to obtain a statistically reliable interval estimate of the concentration of endogenous compounds. A feature of this technique is the use of an exclusively analyzed bioobject for quantitative determination of endogenous substances, without the use of so-called “pure” bioobjects for calibration curves, as well as expensive deuterated analogs of markers – substrates of CYP450 isoenzymes and their metabolites. This allows you to maintain the original biomatrix effect when removing the chromatogram. A statistical apparatus is also used to eliminate possible gross errors. To confirm the reliability of the developed method of quantitative determination, the convergence of the results obtained by this method using deuterated standards is established. Conclusions: A mathematical methodology has been developed for calculating the concentration of endogenous compounds in biological objects measured by chromatography, which allows one to obtain a statistically reliable interval estimate of the concentration of endogenous compounds. A feature of this technique is the use of only the analyzed bioobject for quantitative determination of endogenous substances, which allows you to maintain the original biomatrix effect when removing the chromatogram.Актуальность исследования: Количественное определение эндогенных веществ является важной задачей в экспериментальной и клинической фармакологии. В случае работы с эндогенными соединениями возникают определённые сложности. Главным из них является невозможность получения такой же биоматрицы без эндогенного соединения для использования в качестве эталонных растворов при построении калибровочных кривых. Цель: Цель исследования – разработка математической методики расчёта концентрации эндогенных соединений в биообъектах с помощью хроматографических методов, позволяющей получить статистически достоверную интервальную оценку концентрации эндогенных соединений. Материалы и методы: для реализации вычислительной части предложенного алгоритма используется программа инженерных расчётов Mathcad версии 15.0. Результаты: Разработана математическая методика расчёта концентрации эндогенных соединений в биообъектах с помощью хроматографических методов, которая позволяет получить статистически достоверную интервальную оценку концентрации эндогенных соединений. Особенностью данной методики является использование исключительно анализируемого биообъекта для проведения количественного определения эндогенных веществ, без использования так называемых «чистых» биообъектов для калибровочных кривых, а также дорогостоящих дейтерированных аналогов маркеров – субстратов изоферментов CYP450 и их метаболитов. Это позволяет сохранить оригинальный биоматричных эффект при снятии хроматограммы. Также используется статистический аппарат для исключения возможных грубых ошибок. Для подтверждения достоверности разработанного метода количественного определения установлена сходимость результатов, полученных данным методом и при использовании дейтерированных стандартов. Выводы: Разработана математическая методика расчёта концентрации эндогенных соединений в биообъектах с помощью хроматографических методов, которая позволяет получить статистически достоверную интервальную оценку концентрации эндогенных соединений.