Statistical models and the theory of hypothesis testing in medicine

Purpose: The purpose of this work is to develop statistical approaches for treatment efficiency analysis on a medical case. These methods include the effect evaluation method performed with various preparations in regards to several factors such as the patient‘s blood state and his/her biochemical values. Design/Methodology/Approach: The results of this survey were divided into three groups: the first included the blood biochemistry values before the test, the second — an hour after the test, the the third — two hours after the test. When visually comparing the results of the analyses of the three groups, it was possible to assume that the load of FLC did not significantly affect the biochemistry of the patients' blood. To test this medical assumption, various statistical criteria of the theory of testing statistical hypotheses have been applied. Findings: Statistical analysis of changes in the level of lipase and triglycerides in the biochemical analysis of the blood of patients with chronic pancreatitis after ingestion of food containing medium-chain fatty acids showed that there is no overall disruption in the functioning of the pancreas. Practical implications: Clinical practice has shown that more than 85% of patients tolerated testing with medium chain fatty acids, not experiencing a painful abdominal symptom and other negative consequences of a violation of external secretion of the pancreas. Originality/Value: In clinical practice, the Russian Academy of Medical Sciences for the first time took into account the results of a statistical analysis.peer-reviewe

Local and average fields inside surface-disordered waveguides: Resonances in the one-dimensional Anderson localization regime

We investigate the one-dimensional propagation of waves in the Anderson localization regime, for a single-mode, surface disordered waveguide. We make use of both an analytical formulation and rigorous numerical simulation calculations. The occurrence of anomalously large transmission coefficients for given realizations and/or frequencies is studied, revealing huge field intensity concentration inside the disordered waveguide. The analytically predicted s-like dependence of the average intensity, being in good agreement with the numerical results for moderately long systems, fails to explain the intensity distribution observed deep in the localized regime. The average contribution to the field intensity from the resonances that are above a threshold transmission coefficient $T_{c}$ is a broad distribution with a large maximum at/near mid-waveguide, depending universally (for given $T_{c}$) on the ratio of the length of the disorder segment to the localization length, $L/\xi$. The same universality is observed in the spatial distribution of the intensity inside typical (non-resonant with respect to the transmission coefficient) realizations, presenting a s-like shape similar to that of the total average intensity for $T_{c}$ close to 1, which decays faster the lower is $T_{c}$. Evidence is given of the self-averaging nature of the random quantity $\log[I(x)]/x\simeq -1/\xi$. Higher-order moments of the intensity are also shown.Comment: 9 pages, 9 figure

К МЕТОДИКЕ ОЦЕНКИ ПЕРФУЗИИ МИОКАРДА ЛЕВОГО ЖЕЛУДОЧКА ПРИ ИНФАРКТЕ МИОКАРДА С ПОМОЩЬЮ ОДНОФОТОННОЙ ЭМИССИОННОЙ КОМПЬЮТЕРНОЙ ТОМОГРАФИИ

SUMMARY. On the basis of single photon emission computed tomography of the myocardium (SPECT) with Technetril 99mTc performed in 81 patients with myocardial infarction (MI), we confirmed the proportion of myocardial segments of the left ventricle (LV) with varying degrees of RP inclusion and, therefore, with varying degrees of perfusion impairment. In 75% of patients, reduction of hypoperfusion area in the remote period after myocardial infarction has been revealed compared to the acute period. The relation between slow ECG evolution with the severe impairment of left ventricular myocardial perfusion has been showed. The relation between the degree of impairment of LV myocardial perfusion (by SPECT) and its contraction (according to the two-dimensional echocardiogram) has been revealed. It is shown that one of the leading factors in the restoration of myocardial perfusion is the time of intracoronary intervention. РЕЗЮМЕ. На основании проведения у 81 больного инфарктом миокарда (ИМ) перфузионной однофотонной эмиссионной компьютерной томографии (ОФЭКТ) миокарда с 99mTc-технетрилом уточнено соотношение сегментов миокарда левого желудочка (ЛЖ) с разной степенью включения радиофармпрепарата и, следовательно, с разной степенью нарушения перфузии. У 75% пациентов установлено сокращение площади гипоперфузии в отдаленный период инфаркта по сравнению с острым. Продемонстрирована связь замедленной ЭКГ-эволюции ИМ с глубокими расстройствами перфузии миокарда ЛЖ. Выявлена взаимосвязь степени нарушения перфузии миокарда ЛЖ (по данным ОФЭКТ) и его сократимости (по данным двухмерной Эхо-КГ). Показано, что одним из ведущих факторов восстановления перфузии миокарда является время выполнения внутрико- ронарного вмешательства.

ЧТО ИЗМЕНЯЕТСЯ В ПЕРФУЗИИ И ФУНКЦИИ МИОКАРДА ПОСЛЕ ПОЗДНЕЙ РЕВАСКУЛЯРИЗАЦИИ ОСТРОГО ИНФАРКТА МИОКАРДА?

Aim. To determine the influence of the time gap between acute myocardial infarction with ST-segment elevation and intracoronary intervention performed later than 2.5 hours on myocardium, we studied indicators of perfusion over time with an aid of SPECT, including intraventricular asynchrony (2–4 days and 6–8 months after stent installation).Materials and method. We observed 22 patients with multivessel coronary lesion. The Russian program with the analysis of perfusion, function and the phase images was used in SPECT synchronized with ECG.Results. Showed that the time gap prior to coronary intervention in the acute phase of myocardial infarction may be directly connected with the increase in impaired perfusion during the end-systole and the severity of pathological intraventricular asynchrony without ECG signs. All patients had significantly decreased wall mobility and intraventricular asynchrony together with increased R-R interval in the late period (after 6–8 months) independently from the coronary intervention time. In patients of group 1 (coronary intervention within 6 hours), focal transmural lesions of myocardium significantly decreased.Conclusion. Late revascularization help decrease intraventricular asynchrony reducing the risk of heart failure in future. С целью определения влияния на миокард сроков от острого инфаркта миокарда с подъемом сегмента ST до внутрикоронарного вмешательства, выполненного позднее 2,5 ч, с помощью однофотонной эмиссионной компьютерной томографии (ОФЭКТ) в динамике (на 2–4-е сут и через 6–8 мес после стентирования) изучены параметры перфузии и функции, в том числе внутрижелудочковая асинхрония.Материал и методы. Обследованы 22 пациента с многососудистым поражением коронарного русла. При ОФЭКТ, синхронизированной с электрокардиографией (ЭКГ), использовали отечественную программу с анализом показателей перфузии, функции и фазовых изображений.Результаты. Показано, что время до внутрикоронарного вмешательства в остром периоде инфаркта миокарда может иметь прямую связь с увеличением размеров нарушенной перфузии в конечную систолу и с выраженностью патологической внутрижелудочковой асинхронии миокарда без признаков асинхронии на ЭКГ. Независимо от времени внутрикоронарного вмешательства у всех больных в отдаленном периоде (через 6–8 мес) зарегистрировано значимое уменьшение движения стенки, показателей внутрижелудочковой асинхронии и увеличение интервала R–R. При сравнении исходных и отсроченных данных ОФЭКТ у больных 1-й группы (время менее 6 ч) статистически значимо уменьшались размеры трансмурального очагового поражения миокарда левого желудочка.Заключение. Поздняя реваскуляризация помогает уменьшить внутрижелудочковую асинхронию, снижая риск развития сердечной недостаточности.

БЛИЖАЙШИЕ И ОТДАЛЕННЫЕ РЕЗУЛЬТАТЫ РАЗЛИЧНЫХ СТРАТЕГИЙ ЛЕЧЕНИЯ БОЛЬНЫХ С КРУПНООЧАГОВЫМ ПОВТОРНЫМ ИНФАРКТОМ МИОКАРДА

Aim of study: to assess the effectiveness of invasive treatment strategies in patients with repeated myocardial infarction (rMI). We compared results of three treatment strategies in 453 patients with rMI admitted to the Institute from 2003 to 2011 and analyzed long-term results (up to 2016): 139 roentgen-endovascular coronary interventions (RECI) (various types), including the delayed procedures (performed 24–72 h later), 25 surgical myocardial revascularizations 8–12 weeks after the onset of rMI and 289 cases of conservative therapy. Cardiovascular mortality had been assessed in 138 patients with different treatment strategies for 5 years after the discharge.Findings show that rMI is a predictor of high risk of death associated with high in-hospital and longterm mortality in the absence of reperfusion therapy. RECI in the early stages of rMI does not exclude its later performance. Different types of interventions, including the delayed ones, significantly reduce the incidence of complications and deaths, which occurence remains high in the absence of interventions. however, in a significant portion of patients with rMI, the severity of coronary lesions limits the possibility of RECI performance, determining indications for elective surgical myocardial revascularization. Coronary artery bypass surgery performed after myocardial scarring prevents the growth of left ventricular dysfunction, improves its contractile function, and prolongs the life of patients. Reperfusion strategies such as various types of RECI and/or delayed surgical myocardial revascularization improve the effectiveness of treatment in patients with rMI.Цель исследования: оценка эффективности инвазивных стратегий лечения больных с повторным инфарктом миокарда (пИМ). Проведено сопоставление результатов трех стратегий лечения 453 больных с пИМ, госпитализированных в институт с 2003 по 2011 г. с анализом отдаленных результатов до 2016 г.: различных видов рентгенэндоваскулярных коронарных вмешательств (РКВ), включая отсроченные, выполненные через 24–72 ч (n=139) от начала ИМ; хирургической реваскуляризации миокарда через 8–12 нед от начала пИМ (n=25) и консервативной терапии (n=289). В течение 5 лет после выписки у 138 больных с различными стратегиями лечения оцени- вали общую летальность, в том числе от сердечно-сосудистых заболеваний.Полученные данные свидетельствуют о том, что пИМ является предиктором высокого риска смерти, связанного с отсутствием реперфузионной терапии с высокой госпитальной и отдаленной летальностью. Установлено, что РКВ в ранние сроки пИМ не исключает возможности более позднего их применения. Отсроченные вмешательства существенно сокращают частоту осложнений и смертельных исходов. Вместе с тем, у значительной части больных с пИМ тяжесть поражения коронарного русла ограничивает возможности применения РКВ, определяя показания к хирургической реваскуляризации миокарда. Шунтирование коронарных артерий, выполненное после рубцевания миокарда, предотвращает нарастание дисфункции левого желудочка, улучшает его сократительную функцию и увеличивает продолжительность жизни больных. Применение реперфузионных стратегий в виде различных видов РКВ, в том числе отсроченных и/или хирургической реваскуляризации миокарда позволяет повысить эффективность лечения больных с пИМ

Random-Matrix Theory of Quantum Transport

This is a comprehensive review of the random-matrix approach to the theory of phase-coherent conduction in mesocopic systems. The theory is applied to a variety of physical phenomena in quantum dots and disordered wires, including universal conductance fluctuations, weak localization, Coulomb blockade, sub-Poissonian shot noise, reflectionless tunneling into a superconductor, and giant conductance oscillations in a Josephson junction.Comment: 85 pages including 52 figures, to be published in Rev.Mod.Phy

pH-Dependent Substrate Preference of Pig Heart Lipoamide Dehydrogenase Varies with Oligomeric State: Response to Mitochondrial Matrix Acidification

Cycling of intracellular pH has recently been shown to play a critical role in ischemia-reperfusion injury. Ischemia-reperfusion also leads to mitochondrial matrix acidification and dysfunction. However, the mechanism by which matrix acidification contributes to mitochondrial dysfunction, oxidative stress, and the resultant cellular injury has not been elucidated. We observe pH-dependent equilibria between monomeric, dimeric, and a previously undescribed tetrameric form of pig heart lipoamide dehydrogenase (LADH), a mitochondrial matrix enzyme. Dynamic light scattering studies of native LADH in aqueous solution indicate that lowering pH favors a shift in average molecular mass from higher oligomeric states to monomer. Sedimentation velocity of LADH entrapped in reverse micelles reveals dimer and tetramer at both pH 5.8 and 7.5, but monomer was observed only at pH 5.8. Enzyme activity measurements in reverse Aerosol OT micelles in octane indicate that LADH dimer and tetramer possess lipoamide dehydrogenase and diaphorase activities at pH 7.5. Upon acidification to pH 5.8 only the LADH monomer is active and only the diaphorase activity is ob¬served. These results indicate a correlation between pH-dependent changes in the LADH reaction specificity and its oligomeric state. The acidification of mitochondrial matrix that occurs during ischemia-reperfusion injury is sufficient to alter the structure and enzymatic specificity of LADH, thereby reducing mitochondrial defenses, increasing oxidative stress, and slowing the recovery of energy metabolism. Matrix acidification may also disrupt the quaternary structure of other mitochondrial protein complexes critical for cellular homeostasis and survival