Effect of vitamin E on the blood-brain barrier permeability in aged rats with ptz-induced convulsions

The effect of vitamin E on the blood-brain barrier (BBB) permeability was studied under conditions of pentylenetetrazole (PTZ)-induced convulsions in aged (23- to 24-month-old) male albino rats; Evans Blue was used as a tracer. The BBB permeability was found to considerably increase in rats with PTZ-evoked seizures; the Evans Blue contents in the left and right hemispheres and cerebellum + brainstem region were significantly higher than those in the control. Vitamin E used in the dose of 70 mg/kg exerted practically no beneficial effect on the increased BBB permeability in rats with seizures, while a greater dose of vitamin E (700 mg/kg) exerted a significant protective effect, especially with respect to the cerebellum + brainstem regions (P < 0.01). The seizure-related rise in the arterial blood pressure was also smaller in the latter experimental group. Thus, our observations confirm the importance of the dose of vitamin E as a protective factor for the BBB permeability and demonstrate that the dose dependence of this antioxidant in aged animals dif fers from that in younger or ganisms.На старих (вік 23–24 місяці) самцях білих щурів досліджували вплив вітаміну Е на розлади проникності гематоенцефалічного бар’єра (ГЕБ), пов’язані з розвитком судомної активності, котра була індукована введенням пентилентетразолу (ПТЗ); як трасер використовували барвник Еванс блакитний. У тварин із ПТЗ-викликаними судомами проникність ГЕБ значно збільшувалася; вміст барвника в тканинах лівої та правої мозкових півкуль, мозочка та стовбура мозку вірогідно перевищував відповідні значення в контролі. Вітамін Е в дозі 70 мг/кг практично не справляв позитивного впливу на збільшену проникність ГЕБ у тварин із судомною активністю. Застосування ж вітаміну Е в більших дозах (700 мг/кг) забезпечувало істотний протективний ефект, особливо щодо зразків тканин мозочка та стовбура мозку (P < 0.01). Підвищення артеріального кров’яного тиску, пов’язане з розвитком судом, в останній з експериментальних серій було помірнішим, ніж у двох інших серіях. Отже, наші спостереження підтверджують важливість дозування вітаміну Е як протективного фактора щодо проникності ГЕБ та вказують на те, що залежність від дози цього вітаміну, використовуваного як антиоксидант, у старих тварин істотно відрізняється від такої у молодших організмів

Academic student satisfaction and perceived performance in the e-learning environment during the COVID-19 pandemic: Evidence across ten countries

The outbreak of the COVID-19 pandemic has dramatically shaped higher education and seen the distinct rise of e-learning as a compulsory element of the modern educational landscape. Accordingly, this study highlights the factors which have influenced how students perceive their academic performance during this emergency changeover to e-learning. The empirical analysis is performed on a sample of 10,092 higher education students from 10 countries across 4 continents during the pandemic’s first wave through an online survey. A structural equation model revealed the quality of e-learning was mainly derived from service quality, the teacher’s active role in the process of online education, and the overall system quality, while the students’ digital competencies and online interactions with their colleagues and teachers were considered to be slightly less important factors. The impact of e-learning quality on the students’ performance was strongly mediated by their satisfaction with e-learning. In general, the model gave quite consistent results across countries, gender, study fields, and levels of study. The findings provide a basis for policy recommendations to support decision-makers incorporate e-learning issues in the current and any new similar circumstances.info:eu-repo/semantics/publishedVersio

Archaeogenetic analysis of Neolithic sheep from Anatolia suggests a complex demographic history since domestication

Sheep were among the first domesticated animals, but their demographic history is little understood. Here we analyzed nuclear polymorphism and mitochondrial data (mtDNA) from ancient central and west Anatolian sheep dating from Epipaleolithic to late Neolithic, comparatively with modern-day breeds and central Asian Neolithic/Bronze Age sheep (OBI). Analyzing ancient nuclear data, we found that Anatolian Neolithic sheep (ANS) are genetically closest to present-day European breeds relative to Asian breeds, a conclusion supported by mtDNA haplogroup frequencies. In contrast, OBI showed higher genetic affinity to present-day Asian breeds. These results suggest that the east-west genetic structure observed in present-day breeds had already emerged by 6000 BCE, hinting at multiple sheep domestication episodes or early wild introgression in southwest Asia. Furthermore, we found that ANS are genetically distinct from all modern breeds. Our results suggest that European and Anatolian domestic sheep gene pools have been strongly remolded since the Neolithic

Higher education students’ achievement emotions and their antecedents in e-learning amid COVID-19 pandemic: A multi-country survey

The outbreak of the COVID-19 pandemic has had a wide range of negative consequences for higher education students. We explored the generalizability of the control-value theory of achievement emotions for e-learning, focusing on their antecedents. We involved 17019 higher education students from 13 countries, who completed an online survey during the first wave of the pandemic. A structural equation model revealed that proximal antecedents (e-learning self-efficacy, computer self-efficacy) mediated the relation between environmental antecedents (cognitive and motivational quality of the task) and positive and negative achievement emotions, with some exceptions. The model was invariant across country, area of study, and gender. The rates of achievement emotions varied according to these same factors. Beyond their theoretical relevance, these findings could be the basis for policy recommendations to support stakeholders in coping with the challenges of e-learning and the current and future sequelae of the pandemic.info:eu-repo/semantics/publishedVersio