Diffusion-controlled generation of a proton-motive force across a biomembrane

Respiration in bacteria involves a sequence of energetically-coupled electron and proton transfers creating an electrochemical gradient of protons (a proton-motive force) across the inner bacterial membrane. With a simple kinetic model we analyze a redox loop mechanism of proton-motive force generation mediated by a molecular shuttle diffusing inside the membrane. This model, which includes six electron-binding and two proton-binding sites, reflects the main features of nitrate respiration in E. coli bacteria. We describe the time evolution of the proton translocation process. We find that the electron-proton electrostatic coupling on the shuttle plays a significant role in the process of energy conversion between electron and proton components. We determine the conditions where the redox loop mechanism is able to translocate protons against the transmembrane voltage gradient above 200 mV with a thermodynamic efficiency of about 37%, in the physiologically important range of temperatures from 250 to 350 K.Comment: 26 pages, 4 figures. A similar model is used in arXiv:0806.3233 for a different biological system. Minor changes in the Acknowledgements sectio

Mechanism of the thermochemical transformation of wheat grain’s processing waste during heat treatment

The thermal destruction of wheat grain’s processing wastes from Almaty and South Kazakhstan regions was studieв. The structure of the products obtained depending on the temperature of the carbonization process was formed, and the basic physico chemical characteristics of the obtained carbon material based on the WGPW were studied using thermogravimetric analysis, differential scanning calorimetry, IR spectroscopy and EPR spectroscopy. The analysis of the elemental composition of the obtained samples of the sorption material showed that the carbon content in the composition of the obtained carbon material is 75.08 - 76.12%, which in turn can cause a sufficiently high degree of sorption capacity of this material, as well as its mechanical strength. The obtained carbon materials based on OIP were modified with ammonium nitrate (NH4NO3) to improve its physico-chemical characteristics, such as specific surface area, porosity and adsorption capacity by iodine. It is shown that structural transformations of the processing waste of wheat grain (bran) in the process of heat treatment irrespective of temperature (in the studied interval) proceed through the stage of formation of free radicals. The concentration of free radicals formed in this process, as well as the composition of the graphite-like component of the products obtained, are determined by the temperature indices of the process

Cancer Stem Cells: Emergent Nature of Tumor Emergency

A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of “generalized cellular stress,” which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of “committed” tumor cells

СРАВНИТЕЛЬНЫЙ АНАЛИЗ МЕТОДОВ ХИРУРГИЧЕСКОГО ЛЕЧЕНИЯ ВАРИКОЦЕЛЕ

Introduction. Despite the fact that the existence of varicocele in puberty men, may be one of the risk factors of male infertility the mechanism of spermatogenesis breach remains unclear and should be proved further. Materials and methods. This study conducted a systematic review of randomized researches that are available on PubMed, with the purpose to analyze the optimum choice of surgical techniques to perform varicocelectomy on the basis of the presented results in men suffering from infertility.Results and discussion. According to the literature data the surgical treatment of varicocele in the presence of clinically significant forms leads to a significant improvement of spermatogenesis after 3-6 months surgical treatment. It is worth noting that the effectiveness of varicocelectomy significantly surpasses the results of drug stimulation of spermatogenesis and dynamic monitoring. At present, therefore it is significant to evaluate efficiency and the choice of the optimal method to surgically treat varicocele. According to the results of meta-analysis, it was concluded that the implementation of microsurgical subinguinal varicocelectomy has a number of advantages compared with such methods as Palomo surgery, laparoscopic varicocelectomy, Ivanissevich surgery and selective embolization of sperm veins.Conclusion. Application of microsurgical subinguinal varicocelectomy significantly improves quality and quantity parameters of sperm analysis and, consequently, increases probability of spontaneous pregnancy in partners with minimum percentage of complications, as well as of occurrence of relapse in postoperative period. Введение. Несмотря на тот факт, что наличие варикоцеле в период полового          созревания мужчины, может являться одним из факторов риска развития мужского бесплодия, механизм нарушения сперматогенеза остается до конца не ясным и требует определенных доказательств.Материалы и методы. В данном исследовании был проведен систематический обзор рандомизированных исследований, доступных на PubMed, с целью анализа выбора оптимальной хирургической техники выполнения варикоцелэктомии на          основании представленных результатов у мужчин, страдающих бесплодием.Результаты и их обсуждение. По литературным данным оперативное лечение варикоцеле при наличии клинически значимой формы приводит к достоверному улучшению показателей сперматогенеза уже через 3-6 месяцев после оперативного лечения. Стоит отметить, что эффективность варикоцелэктомии значительно превосходит результаты лекарственной стимуляции сперматогенеза и динамического наблюдения. Поэтому в настоящее время важное значение имеют оценка эффективности и выбор оптимального метода оперативного лечения варикоцеле. По результатам проведенного мет-анализа был сделан вывод о том, что выполнение микрохирургической субингвинальной варикоцелэктомии имеет ряд преимуществ по сравнению с такими методами, как операция Palomo, лапароскопическая варикоцелэктомия, операция Иваниссевича и селективная эмболизация сперматических вен.Заключение. Применение микрохирургической субингвинальной варикоцелэктомии приводит к достоверному улучшению качественных и количественных показателей спермограммы и, как следствие, более высокой по частоте вероятности наступления спонтанной беременности у партнерш, с минимальным процентом развития осложнений, а также возникновения рецидивов в послеоперационном периоде.

Observation of parametric X-rays produced by 400 GeV/c protons in bent crystals

Spectral maxima of parametric X-ray radiation (PXR) produced by 400 GeV/c protons in bent silicon crystals aligned with the beam have been observed in an experiment at the H8 external beam of the CERN SPS. The total yield of PXR photons was about 10-6 per proton. Agreement between calculations and the experimental data shows that the PXR kinematic theory is valid for bent crystals with sufficiently small curvature as used in the experiment. The intensity of PXR emitted from halo protons in a bent crystal used as a primary collimator in a circular accelerator may be considered as a possible tool to control its crystal structure, which is slowly damaged because of irradiation. The intensity distribution of PXR peaks depends on the crystal thickness intersected by the beam, which changes for different orientations of a crystal collimator. This dependence may be used to control crystal collimator alignment by analyzing PXR spectra produced by halo protons.peer-reviewe

ЭХОКАРДИОГРАФИЧЕСКИЕ ПРЕДИКТОРЫ НЕБЛАГОПРИЯТНЫХ КЛИНИЧЕСКИХ СОБЫТИЙ ПРИ СЕРДЕЧНОЙ НЕДОСТАТОЧНОСТИ С СОХРАННОЙ ФРАКЦИЕЙ ВЫБРОСА ЛЕВОГО ЖЕЛУДОЧКА В СОЧЕТАНИИ С СИНДРОМОМ ОБСТРУКТИВНОГО АПНОЭ ВО СНЕ

HighlightsRepeated hospitalizations occupy a special place in adverse clinical events in heart failure, currently representing one of the most powerful predictors of adverse outcomes in this group of patients. Echocardiographic parameters such as longitudinal myocardial deformation, displacement in the annulus of the tricuspid valve, and left atrial volume index can serve as predictors of hospitalization for cardiovascular diseases in patients with heart failure with preserved ejection fraction and obstructive sleep apnea. Abstract Aim. To study the prognostic role of individual echocardiographic parameters in heart failure with preserved ejection fraction (HFpEF) in patients with arterial hypertension and obstructive sleep apnea (OSA).Methods. The study included 59 men with hypertension and OSA (apnea/hypopnea index >15 per hour). At baseline all patients underwent a sleep study and echocardiography with an additional assessment of the global longitudinal strain (GLS). Upon inclusion in the study and after 12 months of follow-up, a 6-minute walk test was performed. After 12 months, the clinical course of the disease was retrospectively assessed. The criteria for an adverse clinical course were episodes of hospitalization for cardiovascular diseases, the development of paroxysmal atrial fibrillation or high-grade ventricular arrhythmias (III–V class according to Ryan), worsening of heart failure with a transition to a higher functional class according to NYHA.Results. Significant differences were found in several echocardiographic parameters between the groups of patients with and without hospitalizations within 12 months of follow-up: tricuspid annular plane systolic excursion (TAPSE) (p = 0.017), GLS (p = 0.005), left atrial volume index (LAVI) (p = 0.032). According to the regression analysis results, TAPSE, GLS and left ventricular ejection fraction make a statistically significant contribution to the probability of hospitalizations among the evaluated echocardiographic predictors.Conclusion. The results of the study allow us to consider certain echocardiographic parameters, in particular GLS, TAPSE and LAVI, as predictors of hospitalizations in patients with HFpEF and OSA.Основные положенияПовторные госпитализации занимают особое место в ряду клинических событий при хронической сердечной недостаточности, представляя в настоящее время один из наиболее мощных предикторов неблагоприятных исходов в этой группе. Эхокардиографические параметры – продольная деформация миокарда левого желудочка, величина смещения фиброзного кольца трикуспидального клапана и индекс объема левого предсердия – служат предикторами госпитализации в стационар по поводу сердечно-сосудистых заболеваний у больных сердечной недостаточностью с сохранной фракцией выброса и синдромом обструктивного апноэ во сне. РезюмеЦель. Изучить прогностическую роль отдельных эхокардиографических параметров при сердечной недостаточности с сохранной фракцией выброса у больных артериальной гипертензией и синдромом обструктивного апноэ во сне (СОАС).Материалы и методы. В исследование включено 59 мужчин с артериальной гипертензией и СОАС (с индексом апноэ/гипопноэ >15 в час). Всем пациентам при включении в исследование выполнены полисомнографическое исследование и эхокардиография с дополнительной оценкой глобальной продольной деформации миокарда левого желудочка (GLS). При включении в исследование и через 12 мес. наблюдения проведен тест 6-минутной ходьбы. Через 12 мес. ретроспективно оценен характер клинического течения заболевания. Критериями неблагоприятного течения являлись эпизоды госпитализации в стационар по поводу сердечно-сосудистых заболеваний, развитие пароксизмальной фибрилляции предсердий или регистрация желудочковых нарушений ритма высоких градаций (III–V класса по Ryan), ухудшение хронической сердечной недостаточности с переходом в более высокий функциональный класс по NYHA.Результаты. Обнаружены значимые различия между группами пациентов с наличием и отсутствием госпитализаций в течение 12 мес. наблюдения по ряду эхокардиографических параметров: систолическому смещению фиброзного кольца трикуспидального клапана (TAPSE) (p = 0,017), GLS (p = 0,005) и индексу объема левого предсердия (p = 0,032). По результатам регрессионного анализа, статистически значимый вклад в вероятность госпитализаций среди оцениваемых эхокардиографических предикторов вносят TAPSE, GLS и фракция выброса левого желудочка.Заключение. Результаты исследования позволяют рассматривать отдельные эхокардиографические параметры, в частности GLS, TAPSE и индекс объема левого предсердия, в качестве предикторов госпитализаций у больных сердечной недостаточностью с сохранной фракцией выброса и СОАС

Rationale and design of the PeriOperative ISchemic Evaluation-3 (POISE-3): a randomized controlled trial evaluating tranexamic acid and a strategy to minimize hypotension in noncardiac surgery

Background For patients undergoing noncardiac surgery, bleeding and hypotension are frequent and associated with increased mortality and cardiovascular complications. Tranexamic acid (TXA) is an antifibrinolytic agent with the potential to reduce surgical bleeding; however, there is uncertainty about its efficacy and safety in noncardiac surgery. Although usual perioperative care is commonly consistent with a hypertension-avoidance strategy (i.e., most patients continue their antihypertensive medications throughout the perioperative period and intraoperative mean arterial pressures of 60 mmHg are commonly accepted), a hypotension-avoidance strategy may improve perioperative outcomes. Methods The PeriOperative Ischemic Evaluation (POISE)-3 Trial is a large international randomized controlled trial designed to determine if TXA is superior to placebo for the composite outcome of life-threatening, major, and critical organ bleeding, and non-inferior to placebo for the occurrence of major arterial and venous thrombotic events, at 30 days after randomization. Using a partial factorial design, POISE-3 will additionally determine the effect of a hypotension-avoidance strategy versus a hypertension-avoidance strategy on the risk of major cardiovascular events, at 30 days after randomization. The target sample size is 10,000 participants. Patients ≥45 years of age undergoing noncardiac surgery, with or at risk of cardiovascular and bleeding complications, are randomized to receive a TXA 1 g intravenous bolus or matching placebo at the start and at the end of surgery. Patients, health care providers, data collectors, outcome adjudicators, and investigators are blinded to the treatment allocation. Patients on ≥ 1 chronic antihypertensive medication are also randomized to either of the two blood pressure management strategies, which differ in the management of patient antihypertensive medications on the morning of surgery and on the first 2 days after surgery, and in the target mean arterial pressure during surgery. Outcome adjudicators are blinded to the blood pressure treatment allocation. Patients are followed up at 30 days and 1 year after randomization. Discussion Bleeding and hypotension in noncardiac surgery are common and have a substantial impact on patient prognosis. The POISE-3 trial will evaluate two interventions to determine their impact on bleeding, cardiovascular complications, and mortality. Trial registration ClinicalTrials.gov NCT03505723. Registered on 23 April 2018

Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised protons

Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise. © 2015