MK-801 and cognitive functions: Investigating the behavioral effects of a non-competitive NMDA receptor antagonist.

RATIONALE: MK-801 (dizocilpine) is a non-competitive NMDA receptor antagonist originally explored for anticonvulsant potential. Despite its original purpose, its amnestic properties led to the development of pivotal models of various cognitive impairments widely employed in research and greatly impacting scientific progress. MK-801 offers several advantages; however, it also presents drawbacks, including inducing dose-dependent hyperlocomotion or ambiguous effects on anxiety, which can impact the interpretation of behavioral research results. OBJECTIVES: The present review attempts to summarize and discuss the effects of MK-801 on different types of memory and cognitive functions in animal studies. RESULTS: A plethora of behavioral research suggests that MK-801 can detrimentally impact cognitive functions. The specific effect of this compound is influenced by variables including developmental stage, gender, species, strain, and, crucially, the administered dose. Notably, when considering the undesirable effects of MK-801, doses up to 0.1 mg/kg were found not to induce stereotypy or hyperlocomotion. CONCLUSION: Dizocilpine continues to be of significant importance in preclinical research, facilitating the exploration of various procognitive therapeutic agents. However, given its potential undesirable effects, it is imperative to meticulously determine the appropriate dosages and conduct supplementary evaluations for any undesirable outcomes, which could complicate the interpretation of the findings.

The psycho-social health of students during first part of COVID-10 pandemy.

INTRODUCTION: In 2020, the world was gripped by a global pandemic caused by a new strain of coronavirus called SARS-CoV-2. Highly contagious, rapidly spreading virus caused massive infections around the world and forced isolation of patients and quarantine of contact persons. Social isolation, caused by the introduction of compulsory distance or resulting from the course of the quarantine process, may result in the loss of emotional ties between individuals, thus leading to the weakening of the social support network. OBJECTIVE: The aim of the study was to assess whether and to what extent the restrictions caused by the first wave of SARS-CoV-2 virus pandemics affected emotional state and everyday behavior of students of Polish universities. MATERIAL AND METHODOLOGY: 1,095 students took part in the study - 82.1% of women and 17.9% men, aged 19 and over up to 55 years of age, living mostly in cities. The diagnostic survey method was applied using proprietary questionnaires. The questionnaire was distributed by Internet. The results were processed using the Statistica v.13.3 program with the application of descriptive statistics and tests χ2 and Anova. RESULTS: According to 80% of respondents, the SARS-CoV-2 pandemic is a serious threat for health. During the first wave of the pandemic, students were accompanied mainly by difficult emotions: uncertainty (61%), depression (28.9%), worry (28.7%), nervousness (37.7%) and anger (24%). According to 50.2%, their relations with household members were not changed, while students declaring changes in family relationships pointed to their loosening and limitation. CONCLUSIONS: A significant majority of students stated that the COVID-19 pandemic is a serious threat to health and has a regular interest in epidemiological data concerning coronavirus. Medical students declared the highest risk. The first wave of the pandemic resulted in the intensification of difficult emotions and for half of the respondents changes in the functioning of their family relationships.

Functional adaptation of crustacean exoskeletal elements through structural and compositional diversity: a combined experimental and theoretical study.

The crustacean cuticle is a composite material that covers the whole animal and forms the continuous exoskeleton. Nano-fibers composed of chitin and protein molecules form most of the organic matrix of the cuticle that, at the macroscale, is organized in up to eight hierarchical levels. At least two of them, the exo- and endocuticle, contain a mineral phase of mainly Mg-calcite, amorphous calcium carbonate and phosphate. The high number of hierarchical levels and the compositional diversity provide a high degree of freedom for varying the physical, in particular mechanical, properties of the material. This makes the cuticle a versatile material ideally suited to form a variety of skeletal elements that are adapted to different functions and the eco-physiological strains of individual species. This review presents our recent analytical, experimental and theoretical studies on the cuticle, summarising at which hierarchical levels structure and composition are modified to achieve the required physical properties. We describe our multi-scale hierarchical modeling approach based on the results from these studies, aiming at systematically predicting the structure-composition-property relations of cuticle composites from the molecular level to the macro-scale. This modeling approach provides a tool to facilitate the development of optimized biomimetic materials within a knowledge-based design approach.

Ultrastructural organization and micromechanical properties of shark tooth enameloid.

The outer part of shark teeth is formed by the hard and mineral-rich enameloid that has excellent mechanical properties, which makes it a very interesting model system for the development of new bio-inspired dental materials. We characterized the microstructure, chemical composition and resulting local mechanical properties of the enameloid from teeth of Isurus oxyrinchus (shortfin mako shark) by performing an in-depth analysis using various high-resolution analytical techniques, including scanning electron microscopy, qualitative energy-dispersive X-ray spectroscopy and nanoindentation. Shark tooth enameloid reveals an intricate hierarchical arrangement of thin (50-80nm) and long (>1µm) crystallites of fluoroapatite with a high degree of structural anisotropy, which leads to exceptional mechanical properties. Both stiffness and hardness are surprisingly homogeneous in the shiny layer as well as in the enameloid: although both tooth phases differ in structure and composition, they show almost no orientation dependence with respect to the loading direction of the enameloid crystallites. The results were used to determine the structural hierarchy of shark teeth, which can be used as a base for establishing design criteria for synthetic bio-inspired and biomimetic dental composites.