Search

Abstract: Surface wettability modifications of biocompatible materials and wettability patterning are attractive methods for directed biological cells immobilization for tissue engineering, drug delivery, gene transfer, etc. Hydroxyapatite is known as an implantable biomimetic material and a substrate for effective adhesion of biological cells of various origins. Here we report the use of a low-energy electron irradiation to achieve tunable wettability of the hydroxyapatite in a wide range of contact angles, from 10° to 100°, with accuracy of ±3°. The incident electrons generate electron/hole pairs resulting in significant variation of the surface potential of the hydroxyapatite semiconductor and give rise to pronounced wettability modification. Tailoring the gradually varied wettability state in the hydroxyapatite nanoceramics enabled the differential binding of biological materials with different surface properties, such as bovine serum albumin (BSA) and deoxyribonucleic acid (DNA). [Copyright &y& Elsevier]

Chemical surface reactivity is a key parameter in modern microelectronic and display technology that is defined by basic physical interactions at the liquid etcher/material surface interface. We apply recently developed low-energy electron irradiation method for surface modification of zinc oxide-based thin films affording to vary physical processes at the liquid agent/material surface interface/and widely tune its chemical reactivity. Electron irradiation leads to the formation of ultrathin layer on irradiated surface, without generation of volumetric defects, and preserves original optical and conductive properties. The method allows fabrication of high-resolution patterned templates with modified chemical etching resistance for the fabrication of three-dimensional patterned arrays. [ABSTRACT FROM AUTHOR]

Electric charges deposited on a liquid droplet, located on a solid surface, strengthen the wetting effect. Here, the authors report on the opposite phenomenon—a decrease of wettability induced by a low-energy electron irradiation of solids. They provide evidence that the electron-induced surface charge decreases solid/liquid and solid/vapor interfacial energies when reduction of the latter is always higher. This explains the observed dependence of the droplet shape on the incident electron charge and energy, as well as on a liquid origin. This phenomenon is reversible when the charged material is subjected to ultraviolet illumination, which restores its initial state. [ABSTRACT FROM AUTHOR]

Hydroxyapatite is known as a substrate for effective adhesion of various biological cells and bacteria as well implantable biomimetic material replacing defective bone tissues. It is found that low energy electron irradiation induces its strong surface potential variation and gives rise to pronounced wettability modification. The found electron-modulation method of the hydroxyapatite wettability enables both wettability switching and its microscopic patterning, which may be used for fabrication of spatially arrayed hydroxyapatite for biological cells immobilization, gene transfer, etc. [ABSTRACT FROM AUTHOR]

Forming an episodic memory requires binding together disparate elements that co-occur in a single experience. One model of this process is that neurons representing different components of a memory bind to an "index" - a subset of neurons unique to that memory. Evidence for this model has recently been found in chickadees, which use hippocampal memory to store and recall locations of cached food. Chickadee hippocampus produces sparse, high-dimensional patterns ("barcodes") that uniquely specify each caching event. Unexpectedly, the same neurons that participate in barcodes also exhibit conventional place tuning. It is unknown how barcode activity is generated, and what role it plays in memory formation and retrieval. It is also unclear how a memory index (e.g. barcodes) could function in the same neural population that represents memory content (e.g. place). Here, we design a biologically plausible model that generates barcodes and uses them to bind experiential content. Our model generates barcodes from place inputs through the chaotic dynamics of a recurrent neural network and uses Hebbian plasticity to store barcodes as attractor states. The model matches experimental observations that memory indices (barcodes) and content signals (place tuning) are randomly intermixed in the activity of single neurons. We demonstrate that barcodes reduce memory interference between correlated experiences. We also show that place tuning plays a complementary role to barcodes, enabling flexible, contextually-appropriate memory retrieval. Finally, our model is compatible with previous models of the hippocampus as generating a predictive map. Distinct predictive and indexing functions of the network are achieved via an adjustment of global recurrent gain. Our results suggest how the hippocampus may use barcodes to resolve fundamental tensions between memory specificity (pattern separation) and flexible recall (pattern completion) in general memory systems.

The hippocampus is critical for episodic memory. Although hippocampal activity represents place and other behaviorally relevant variables, it is unclear how it encodes numerous memories of specific events in life. To study episodic coding, we leveraged the specialized behavior of chickadees-food-caching birds that form memories at well-defined moments in time whenever they cache food for subsequent retrieval. Our recordings during caching revealed very sparse, transient barcode-like patterns of firing across hippocampal neurons. Each "barcode" uniquely represented a caching event and transiently reactivated during the retrieval of that specific cache. Barcodes co-occurred with the conventional activity of place cells but were uncorrelated even for nearby cache locations that had similar place codes. We propose that animals recall episodic memories by reactivating hippocampal barcodes. Similarly to computer hash codes, these patterns assign unique identifiers to different events and could be a mechanism for rapid formation and storage of many non-interfering memories., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The mammalian hippocampal formation (HF) is organized into domains associated with different functions. These differences are driven in part by the pattern of input along the hippocampal long axis, such as visual input to the septal hippocampus and amygdalar input to the temporal hippocampus. HF is also organized along the transverse axis, with different patterns of neural activity in the hippocampus and the entorhinal cortex. In some birds, a similar organization has been observed along both of these axes. However, it is not known what role inputs play in this organization. We used retrograde tracing to map inputs into HF of a food-caching bird, the black-capped chickadee. We first compared two locations along the transverse axis: the hippocampus and the dorsolateral hippocampal area (DL), which is analogous to the entorhinal cortex. We found that pallial regions predominantly targeted DL, while some subcortical regions like the lateral hypothalamus (LHy) preferentially targeted the hippocampus. We then examined the hippocampal long axis and found that almost all inputs were topographic along this direction. For example, the anterior hippocampus was preferentially innervated by thalamic regions, while the posterior hippocampus received more amygdalar input. Some of the topographies we found bear a resemblance to those described in the mammalian brain, revealing a remarkable anatomical similarity of phylogenetically distant animals. More generally, our work establishes the pattern of inputs to HF in chickadees. Some of these patterns may be unique to chickadees, laying the groundwork for studying the anatomical basis of these birds' exceptional hippocampal memory., (© 2023 Wiley Periodicals LLC.)

Episodic memory, or memory of experienced events, is a critical function of the hippocampus 1-3 . It is therefore important to understand how hippocampal activity represents specific events in an animal's life. We addressed this question in chickadees - specialist food-caching birds that hide food at scattered locations and use memory to find their caches later in time 4,5 . We performed high-density neural recordings in the hippocampus of chickadees as they cached and retrieved seeds in a laboratory arena. We found that each caching event was represented by a burst of firing in a unique set of hippocampal neurons. These 'barcode-like' patterns of activity were sparse (<10% of neurons active), uncorrelated even for immediately adjacent caches, and different even for separate caches at the same location. The barcode representing a specific caching event was transiently reactivated whenever a bird later interacted with the same cache - for example, to retrieve food. Barcodes co-occurred with conventional place cell activity 6,7 , as well as location-independent responses to cached seeds. We propose that barcodes are signatures of episodic memories evoked during memory recall. These patterns assign a unique identifier to each event and may be a mechanism for rapid formation and storage of many non-interfering memories.

The mammalian entorhinal cortex routes inputs from diverse sources into the hippocampus. This information is mixed and expressed in the activity of many specialized entorhinal cell types, which are considered indispensable for hippocampal function. However, functionally similar hippocampi exist even in non-mammals that lack an obvious entorhinal cortex or, generally, any layered cortex. To address this dilemma, we mapped extrinsic hippocampal connections in chickadees, whose hippocampi are used for remembering numerous food caches. We found a well-delineated structure in these birds that is topologically similar to the entorhinal cortex and interfaces between the hippocampus and other pallial regions. Recordings of this structure revealed entorhinal-like activity, including border and multi-field grid-like cells. These cells were localized to the subregion predicted by anatomical mapping to match the dorsomedial entorhinal cortex. Our findings uncover an anatomical and physiological equivalence of vastly different brains, suggesting a fundamental nature of entorhinal-like computations for hippocampal function., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The predictive nature of the hippocampus is thought to be useful for memory-guided cognitive behaviors. Inspired by the reinforcement learning literature, this notion has been formalized as a predictive map called the successor representation (SR). The SR captures a number of observations about hippocampal activity. However, the algorithm does not provide a neural mechanism for how such representations arise. Here, we show the dynamics of a recurrent neural network naturally calculate the SR when the synaptic weights match the transition probability matrix. Interestingly, the predictive horizon can be flexibly modulated simply by changing the network gain. We derive simple, biologically plausible learning rules to learn the SR in a recurrent network. We test our model with realistic inputs and match hippocampal data recorded during random foraging. Taken together, our results suggest that the SR is more accessible in neural circuits than previously thought and can support a broad range of cognitive functions., Competing Interests: CF, DA, LA, EM No competing interests declared, (© 2023, Fang et al.)

Aim: A high-fat diet (HFD) is generally considered to negatively influence the body, the brain, and cognition. Nonetheless, fat and fatty acids are essential for nourishing and constructing brain tissue. Astrocytes are central for lipolysis and fatty acids metabolism. We tested how HFD affects astrocyte metabolism, morphology, and physiology., Methods: We used Raman microspectroscopy to assess the redox state of mitochondria and lipid content in astrocytes and neurons in hippocampal slices of mice subjected to HFD. Astrocytes were loaded with fluorescent dye through patch pipette for morphological analysis. Whole-cell voltage-clamp recordings were performed to measure transporter and potassium currents. Western blot analysis quantified the expression of astrocyte-specific proteins. Field potential recordings measured the magnitude of long-term potentiation (LTP). Open filed test was performed to evaluate the effect of HFD on animal behavior., Results: We found that exposure of young mice to 1 month of HFD increases lipid content and relative amount of reduced cytochromes in astrocytes but not in neurons. Metabolic changes were paralleled with an enlargement of astrocytic territorial domains due to an increased outgrowth of branches and leaflets. Astrocyte remodeling was associated with an increase in expression of ezrin and with no changes in glial fibrillary acidic protein (GFAP), glutamate transporter-1 (GLT-1), and glutamine synthetase (GS). Such physiological (non-reactive) enlargement of astrocytes in the brain active milieu promoted glutamate clearance and LTP and translated into behavioral changes., Conclusion: Dietary fat intake is not invariably harmful and might exert beneficial effects depending on the biological context., (© 2022 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)

Animals use memory-guided and memory-independent strategies to make navigational decisions. Disentangling the contribution of these strategies to navigation is critical for understanding how memory influences behavioral output. To address this issue, we studied spatial behaviors of the chickadee, a food-caching bird. Chickadees hide food in concealed, scattered locations and retrieve their caches later in time. We designed an apparatus that allows birds to cache and retrieve food at many sites while navigating in a laboratory arena. This apparatus enabled automated tracking of behavioral variables - including caches, retrievals, and investigations of different sites. We built probabilistic models to fit these behavioral data using a combination of mnemonic and non-mnemonic factors. We found that chickadees use some navigational strategies that are independent of cache memories, including opportunistic foraging and spatial biases. They combine these strategies with spatially precise memories of which sites contain caches and which sites they have previously checked. A single memory of site contents is used in a context-dependent manner: during caching chickadees avoid sites that contain food, while during retrieval they instead preferentially access occupied sites. Our approach is a powerful way to investigate navigational decisions in a natural behavior, including flexible contributions of memory to these decisions., Competing Interests: MA, DA No competing interests declared, (© 2022, Applegate and Aronov.)

Aim      To evaluate efficacy of modified-release trimetazidine (TMZ) included into the standard therapy for patients with stable angina and chronic heart failure (CHF) as a part of a subgroup analysis in the PERSPECTIVE study.Material and methods  The study included 806 patients: group 1 (n=691), patients receiving a standard therapy and modified-release TMZ (TMZ group); and group 2 (n=115), patients receiving a standard therapy (control group). Total duration of the study was 12 months.Results In the TMZ group, the weekly number of angina attacks decreased by 41.9% (p&lt;0.0001) in 2 months and by 69.6 % (from baseline, р&lt;0.0001) in 12 months, and the frequency of nitroglycerine dosing decreased by 40.8 % (р&lt;0.0001) and 67.7 % (р&lt;0.0001), respectively. In the control group, the respective values did not change. In the TMZ group compared to the control group, the QT interval was shorter (7.9 %; р&lt;0.05), the left ventricular (LV) end-systolic dimension was reduced (13.4 %; р&lt;0.01), interventricular septal thickness and LV posterior wall thickness were decreased (9.5 %; р&lt;0.01 and 12.2 %; р&lt;0.01, respectively), and the ejection fraction was increased (11.4; р&lt;0.05). Following the TMZ treatment, the leukocyte count in peripheral blood was decreased (5.3 %; р&lt;0.01) and the serum concentration of high-sensitivity C-reactive protein was decreased (30.7 %; р&lt;0.01) vs. increases of these indexes in the control group (17.9 %; р&lt;0.05 and 17.8 %; р&lt;0.05, respectively). The proportion of patients hospitalized for exacerbation of CHF or angina for 12 months was 8.6 % in the TMZ group and 15.7 % in the control group (p=0,001).Conclusion      In patients with stable angina and CHF, inclusion of modified-release TMZ into the standard therapy decreases the number of angina attacks, reduces the activity of inflammatory factors, and improves the course of disease.

The aim of this study was to compare the biodistribution in mice of functionalized rhodamine B (Rh) labeled colchicine derivative furano-allocolchicinoid ( AC , 6 ) either conjugated to 40 kDa chitosan ( AC-Chi , 8 ) or encapsulated into chitosan nanoparticles ( AC-NPs ). AC-NPs were formed by ionotropic gelation and were 400-450 nm in diameter as estimated in mice by dynamic light scattering and confocal microscopy. AC-Chi and AC-NPs preserved the specific colchicine activity in vitro. AC preparations were once IV injected into C75BL/6 mice; muscles, spleen, kidney, liver, lungs, blood cells and serum were collected at 30 min, 2, 5, 10, and 20 h post injection. To analyze the distribution of the furano-allocolchicinoid preparations in body liquids and tissues, Rh was measured directly in sera or extracted by acidic ethanol from tissue homogenates. Preliminary Rh extraction rate was estimated in vitro in tissue homogenates and was around 25-30% from total quantity added. After in vivo injection, AC-NPs were accumulated more in liver and spleen, while less in kidney and lungs in comparison with free AC and AC-Chi. Therefore, incorporation of colchicine derivatives as well as other hydrophobic substances into nano/micro sized carriers may help redistribute the drug to different organs and, possibly, improve antitumor accumulation.

Comprehensive descriptions of animal behavior require precise three-dimensional (3D) measurements of whole-body movements. Although two-dimensional approaches can track visible landmarks in restrictive environments, performance drops in freely moving animals, due to occlusions and appearance changes. Therefore, we designed DANNCE to robustly track anatomical landmarks in 3D across species and behaviors. DANNCE uses projective geometry to construct inputs to a convolutional neural network that leverages learned 3D geometric reasoning. We trained and benchmarked DANNCE using a dataset of nearly seven million frames that relates color videos and rodent 3D poses. In rats and mice, DANNCE robustly tracked dozens of landmarks on the head, trunk, and limbs of freely moving animals in naturalistic settings. We extended DANNCE to datasets from rat pups, marmosets, and chickadees, and demonstrate quantitative profiling of behavioral lineage during development.

Objective: To measure progress towards introducing a 3-phase rehabilitation programme, based on the multidisciplinary approach, for patients with cardiovascular diseases., Methods: Seventeen hospital and outpatient medical centres from 13 regions of the Pilot Project. Baseline questionnaires assessed the involvement of multidisciplinary teams, staffing, and the equipment in healthcare facilities. These questionnaires covered 3 rehabilitation phases: inpatient rehabilitation in the intensive care units and departments of myocardial infarction/cardiac surgery; early in-hospital rehabilitation; and outpatient rehabilitation., Results: The pilot project was initiated in 2013. At the 5-year follow-up, phase I was established across all 17 sites, phase II at 13 sites, and phase III at 9 sites. By 2017, multidisciplinary teams were deployed to manage patients at all sites. Early rehabilitation in regional vascular centres, reduced patients' stay from 13.7 (2.1) days in 2013 to 7.6 (1.1) days in 2017., Conclusion: Despite successful implementation of the 3-phase rehabilitation programme based on the multidisciplinary approach, further improvement is required, with the main focus shifted to patients routing between healthcare facilities. Particular attention should be paid to the standards for providing phase III cardiac rehabilitation, in order to ensure continuity of cardiac rehabilitation. The next step should include assessment of the effectiveness of the implemented cardiac rehabilitation programme and its translation to other regions of the country.