MORPHOLOGICAL SUBSTANTIATION OF THE POSSIBILITY OF CREATING A BILATERAL MODEL OF ISCHEMIA- REPERFUSION

Цель - выявить и изучить степень выраженности морфологических изменений структур коркового и мозгового вещества почки на фоне смоделированной билатеральной модели ишемии-реперфузии. Материал и методы. Эксперименты проведены на 50 крысах-самцах линии Вистар массой 180-220 г. Моделирование билатеральной модели ишемии-реперфузии проводилось путем наложения атравматичных зажимов на обе почечные ножки на 40 мин. Через 24 или 72 ч реперфузии проводили оценку выраженности структурных изменений в корковом и мозговом веществе почки с использованием гистологических и морфометрических методик. Измеряли высоту эпителиоцитов в проксимальном и дистальном извитых канальцах нефрона, площадь поперечного сечения почечного тельца, клубочка и капсулярного пространства. Результаты. Полученные морфологические изменения в виде нарушения структурности эпителия как в корковом, так и в мозговом веществе почки на 1-е сутки эксперимента имеют тенденцию к увеличению степени их выраженности. К 3-м суткам эксперимента наиболее выраженные реактивно-деструктивные изменения визуализируются в реабсорбционносекреторных отделах нефрона, которые проявляются в виде снижения высоты эпителиоцитов проксимальных и дистальных канальцев, отслоением их от базальной мембраны и слущиванием. Усугубление схожей морфологической картины происходило в собирательных трубках, в просветах которых определялись конгломераты из отслоившихся от базальной мембраны погибших клеток эпителия. Выявленные реактивно-деструктивные изменения в почках морфологически обосновывают адекватность создания модели ишемии-реперфузии. Выводы. 40-минутная билатеральная ишемия почек с последующей реперфузией в течение 1-3 сут приводит к выраженным структурным изменениям в почках, что соответствует характеристике острого почечного повреждения. Objective - to identify and study the severity of morphological changes in the structures of the renal cortex and medulla in the bilateral model of ischemia-reperfusion. Material and methods. The experiments were performed on 50 male Wistar rats weighing 180-220 grams. A bilateral ischemia-reperfusion was modelled by applying atraumatic clamps to both kidney pedicles for 40 minutes. After 24 or 72 hours of reperfusion, the severity of structural changes in the renal cortex and medulla was assessed using histological and morphometric techniques. The height of epithelial cells in the proximal and distal convoluted tubules of the nephron, the cross-sectional area of the renal corpuscle, glomerulus and capsular space were measured. Results. Severe structural changes in the renal tissue affecting both the tubular and glomerular apparatus of the kidneys were found, with the increase in pathological changes from the first to the third days of the experiment in the form of a decrease in the epithelial height of the distal and proximal tubules, as well as a decrease in the area of the renal corpuscle and vascular glomerulus. The morphological changes in the form of a structural damage of the epithelium of both renal cortex and medulla were detected on the 1st day of the experiment, and they tend to increase their severity. By the 3rd day of the experiment, the most pronounced reactive-destructive changes were visualized in the reabsorption-secretory sections of the nephron. They were manifested as a decrease in the height of the proximal and distal tubule epithelial cells, their exfoliation from the basement membrane and desquamation. The similar but more aggravated morphological picture was seen in collecting tubes, where conglomerates of dead epithelial cells exfoliated from the basement membrane were found in the gaps. The revealed reactive-destructive changes in the kidneys morphologically substantiate the adequacy of creating a model of ischemia-reperfusion. Conclusions. A 40-minute bilateral renal ischemia followed by reperfusion leads to severe structural changes in the kidneys in 1-3 days, which corresponds to a characteristic of acute renal damage.

A unified neurocomputational bilateral model of spoken language production in healthy participants and recovery in post-stroke aphasia

Understanding the processes underlying normal, impaired and recovered language performance has been a long-standing goal for cognitive and clinical neuroscience. Many verbally-described hypotheses about language lateralisation and recovery have been generated. However, they have not been considered within a single, unified and implemented computational framework, and the literatures on healthy participants and patients are largely separated. These investigations also span different types of data, including behavioural results and fMRI brain activations, which augment the challenge for any unified theory. Consequently, many key issues, apparent contradictions and puzzles remain to be solved. We developed a neurocomputational, bilateral pathway model of spoken language production, designed to provide a unified framework to simulate different types of data from healthy participants and aphasic patients. The model encapsulates key computational principles (differential computational capacity, emergent division of labour across pathways, experience-dependent plasticity-related recovery) and provides an explanation for the bilateral yet asymmetric lateralisation of language in healthy participants, chronic aphasia after left rather than right hemisphere lesions, and the basis of partial recovery in patients. The model provides a formal basis for understanding the relationship between behavioural performance and brain activation. The unified model is consistent with the degeneracy and variable neuro-displacement theories of language recovery, and adds computational insights to these hypotheses regarding the neural machinery underlying language processing and plasticity-related recovery following damage.Significance StatementStudies of healthy and impaired language have generated many verbally-described hypotheses. Whilst these verbal descriptions have advanced our understanding of language processing, some explanations are mutually incompatible and it is unclear how they work mechanistically. We constructed a neurocomputational bilateral model of spoken language production to simulate a range of phenomena in healthy participants and patients with aphasia simultaneously, including language lateralisation, impaired performance after left but not right damage, and hemispheric involvement in plasticity-dependent recovery. The model demonstrates how seemly contradictory findings can be simulated within a single framework. To our knowledge, this provides the first coherent mechanistic account of language lateralisation and recovery from post-stroke aphasia.

A study on the performance evaluation of major international airports in the world

PurposeThis paper aims to assess the performance evaluation of major international airports in the world.Design/methodology/approachIn this study, the authors utilized data envelopment analysis in an input‐oriented method to discuss the overall operational performance of 20 major international airports between 2001 and 2005. They used cross efficiency measure to determine the international airports that enjoy the best operational performances and used the bilateral model to compare the performance differences between international airports of different regions.FindingsThe Atlanta Airport (ATL) in the USA and the Beijing Airport (PEK) in China experienced MPSS. The overall performance of international airports in Asia is better than those in Americas, Europe, and Oceania.Research limitations/implicationsService quality can be discuss in the field in the future.Practical implicationsIn sensitivity analysis, four inputs had positive impacts on overall performances.Originality/valueThe ATL in the USA and the PEK in China were the best practices for the other international airports.