The N-methyl-d-aspartate receptor antagonist CPP alters synapse and spine structure and impairs long-term potentiation and long-term depression induced morphological plasticity in dentate gyrus of the awake rat

Long-term morphological synaptic changes associated with homosynaptic long-term potentiation (LTP) and heterosynaptic long-term depression (LTD) in vivo, in awake adult rats were analyzed using three-dimensional (3-D) reconstructions of electron microscope images of ultrathin serial sections from the molecular layer of the dentate gyrus. For the first time in morphological studies, the specificity of the effects of LTP and LTD on both spine and synapse ultrastructure was determined using an N-methyl-d-aspartate (NMDA) receptor antagonist CPP (3-[(R)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid). There were no differences in synaptic density 24 h after LTP or LTD induction, and CPP alone had no effect on synaptic density. LTP increased significantly the proportion of mushroom spines, whereas LTD increased the proportion of thin spines, and both LTP and LTD decreased stubby spine number. Both LTP and LTD increased significantly spine head evaginations (spinules) into synaptic boutons and CPP blocked these changes. Synaptic boutons were smaller after LTD, indicating a pre-synaptic effect. Interestingly, CPP alone decreased bouton and mushroom spine volumes, as well as post-synaptic density (PSD) volume of mushroom spines.These data show similarities, but also some clear differences, between the effects of LTP and LTD on spine and synaptic morphology. Although CPP blocks both LTP and LTD, and impairs most morphological changes in spines and synapses, CPP alone was shown to exert effects on aspects of spine and synaptic structure

Topical Issues for Particle Acceleration Mechanisms in Astrophysical Shocks

Particle acceleration at plasma shocks appears to be ubiquitous in the universe, spanning systems in the heliosphere, supernova remnants, and relativistic jets in distant active galaxies and gamma-ray bursts. This review addresses some of the key issues for shock acceleration theory that require resolution in order to propel our understanding of particle energization in astrophysical environments. These include magnetic field amplification in shock ramps, the non-linear hydrodynamic interplay between thermal ions and their extremely energetic counterparts possessing ultrarelativistic energies, and the ability to inject and accelerate electrons in both non-relativistic and relativistic shocks. Recent observational developments that impact these issues are summarized. While these topics are currently being probed by astrophysicists using numerical simulations, they are also ripe for investigation in laboratory experiments, which potentially can provide valuable insights into the physics of cosmic shocks.Comment: 13 pages, no figures. Invited review, accepted for publication in Astrophysics and Space Science, as part of the HEDLA 2006 conference proceeding

Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia–normothermia in vivo: A three-dimensional electron microscope study

A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2–4 °C), or after warming and recovery to the normothermic state (34 °C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 °C at which time core rectal temperature was 15 °C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal

Peculiarities of structure and thermomechanical strengthening of martensitic structural steels microalloyed by nitrogen

The effect of thermomechanical treatments on structure and properties of structural C(0.35-0.50)CrNiMoV steels microalloyed by nitrogen were studied using optical microscopy, X-ray diffraction analysis and mechanical testing. The hardness of martensite change as a function of austenitization temperature is presented for the steels with the same main composition but various summary C and N contents. Microalloying of structural steels by nitrogen results in complication of phase transformations and raising austenitization temperature for quenching and HTMT. A small quantity of undissolved carbonitrides promotes fine-grained structure preservation and heredity of the initial ascast structure. The heat and thermomechanical treatment regimes were determined which allowed the use of nitrogenmicroalloyed structural steels as high-strength ones. A complete dissolution of special carbonitrides during HTMT and following low-temperature tempering provide high strength level (by 300-500 MPa higher than for nitrogen-free analogs) combined with sufficient ductility and fracture toughness

Sleep Disorders in Post-COVID Syndrome: A Psychiatric or Neurological Problem?

The coronavirus pandemic that began in 2019 continues. COVID-19 adversely affects human health not only in the acute, but also in the long-term period of the disease: in a large percentage of cases, health is not fully restored after long periods, requires medical intervention, and is often difficult to correct. Researchers noted during the first wave of the pandemic in 2020 that about 10–20% of patients did not fully recover by three weeks from disease onset and the possible duration of the recovery period remains insufficiently clear, as do the reasons for differences in course during this period. Prolonged recovery after viral infection is not a feature exclusive to COVID-19, which does not facilitate the management of patients with post-COVID syndrome (PCS). The mental health impact of COVID-19 is significant, with at least 30% of recovered patients likely to have symptoms of anxiety and/or depression after the acute phase has passed. Since the onset of COVID-19, there has been an increase in sleep disorders by 42%, with every third COVID-19 survivor reporting sleep complaints. In PCS, this condition is referred to as coronasomnia. The success of therapy for this condition depends on identifying and correcting patients’ mental disorders, as anxiety and depression are often accompanied by sleep disorders this results in a bidirectional interaction between mental disorders and sleep quality. This article presents data on the anti-anxiety drugs Noofen and Adaptol, which help to correct the manifestations of PCS with sleep disorders

Sleep disorders in post-COVID syndrome - a problem of psychiatry or neurology? [Rasstroistva sna pri postkovidnom sindrome — problema psikhiatrii ili nevrologii?]

The pandemic of coronavirus infection, which has begun in 2019, has not ended to this day. COVID-19 adversely affects human health not only in the acute period of the disease, but also in the long-run: in a large percentage of cases, recovery takes very long, patients require and often have problems returning to their baseline. During the first wave of the pandemic in 2020, researchers noted that about 10-20% of patients didn't fully recover three weeks after the onset of the disease. It is still not clear how long the recovery period can last, and what are the reasons of different time course of the recovery. Long-term recovery after a viral infection is a non-unique feature of COVID-19, which does not facilitate the management of patients with post-COVID syndrome. The impact on mental health after COVID-19 is significant, and at least 30% of those, who have been ill, may have symptoms of anxiety and/or depression after the acute phase of the disease. Since the emergence of the SARS-CoV-2 virus, there has been an increase in somnological disorders by 42%, while every third COVID-19 patient reports altered sleep patterns. In post-COVID-19 syndrome, this condition is referred to as Coronasomnia (COVID-somnia). The success of therapy of this condition depends on reporting and treating mental disorders in patients, as anxiety and depression are often accompanied by sleep disorders, that is, there is a bidirectional influence of mental disorders on the quality of sleep. The article provides data on two anti-anxiety drugs (noofen and adaptol) that help to treat the manifestations of post-COVID syndrome accompanied by sleep disorders.Пандемия коронавирусной инфекции, начавшаяся в 2019 г., по сей день не завершилась. COVID-19 пагубно влияет на здоровье человека не только в острый, но и в отдаленный период заболевания: в большом проценте случаев здоровье полностью не восстанавливается длительное время, требует медицинского вмешательства, зачастую трудно поддается коррекции. Исследователи еще во время первой волны пандемии в 2020 г. отметили, что около 10—20% пациентов не полностью выздоровели через 3 нед от начала заболевания, до сих пор недостаточно ясно, как долго может длиться период выздоровления, и причины разного течения этого периода. Длительное восстановление после перенесенной вирусной инфекции не является исключительной особенностью COVID-19, что не облегчает курацию пациентов с постковидным синдромом (ПКС). Влияние на психическое здоровье перенесенного COVID-19 значительно, по крайней мере, у 30% переболевших могут быть симптомы тревоги и/или депрессии после минования острой фазы. С момента появления COVID-19 отмечено увеличение сомнологических расстройств на 42%, при этом каждый 3-й переболевший COVID-19 отмечает жалобы со стороны сна. При ПКС такое состояние обозначают как Coronasomnia (коронасомния). Успех терапии этого состояния зависит от учета и коррекции психических расстройств у пациента, так как тревога и депрессия часто сопровождаются нарушениями сна, существует двунаправленное влияние психических расстройств на качество сна. В статье приводятся данные о противотревожных препаратах Ноофен и Адаптол, помогающих корректировать проявления ПКС с расстройствами сна

Cobalt(III) Complexes as Bifunctional Hydrogen-Bond Donor Catalysts Featuring Halide Anions for Cyclic Carbonate Synthesis at Ambient Temperature and Pressure: A Mechanistic Insight

The metal-templated hydrogen bond donors (HBD) are prospective catalytic systems for the activation of organic molecules in chemical reactions. Here we report the application of the chiral cationic Co(III) complexes based on commercially available (S,S)-1,2-diaminocyclohexane and (R,R)-1,2-diphenylethylendiamine and salicylaldehydes with an iodide counter-anion as bifunctional one-component hydrogen bond donor/nucleophilic catalysts for the conversion of carbon dioxide with epoxides into valuable cyclic carbonates under solvent- and co-catalyst free conditions. We demonstrated that (R,R)-1,2-diphenylethylendiamine based complex Λ(R,R)-2 is superior to (S,S)-1,2-diaminocyclohexane based Δ(S,S)-1 a catalyzing the reaction at ambient conditions (RT and 1 bar CO2). The TON and TOF values of 850 and 35 h−1, respectively, were achieved at low catalyst loading (0.1 mol %) at 10 bars of CO2 and 100 °C. Furthermore, the Co(III) complexes catalyzed the reaction with diluted air/CO2 mixture (15 vol % of CO2) producing the desired styrene carbonate in up to 75% yield. A plausible catalytic cycle consistent with all experimental observations was proposed based on DFT calculations. The DFT calculations elucidated the difference in the ring opening step in cases of propylene oxide and styrene oxide. In addition, the kinetic resolution of terminal epoxides was observed with selectivity factor (s) of up to 1.6 in case of the complex Λ(R,R)-2. © 2022 Wiley-VCH GmbH

Stress increases 'Axo-spinous' post-synaptic density size in CA1 stratum lacunosum-moleculare: a three-dimensional ultrastructural study [poster presentation]

Stress alters the synaptic connectivity of hippocampal neurones (Sandi et al., Euro. J. Neurosci. 17: 2446-2476). Stereological studies in our laboratory indicate that chronic restraint stress (CRS; 6h/day, 21days) significantly increases the size of the post-synaptic density (PSD) membranes of asymmetric axo-spinous synapses in dorsal anterior CA1 stratum lacunosum-moleculare. No change occured in the absolute number of these synapses between groups. To further characterise these stress-associated synaptic alterations, 3-D reconstructions of asymmetric axo-spinous PSD membranes were performed using electron-microscope images obtained from serial ultrathin sections. Thirty synapses per animal were reconstructed (4 animals per group). The associated dendritic spines of the identified synapses were also reconstructed in 3-D. Our preliminary findings indicate a significant increase in PSD membrane surface area of asymmetric axo-spinous synapses following CRS (+36%; p=0.026) and a highly significant increase in PSD membrane volume (+77%; p=0.003). No significant alterations were detected in the surface area or volume of reconstructed dendritic spines. These results verify our earlier stereological findings that CRS significantly increases the size of asymmetric axo-spinous synaptic junctions in dorsal-anterior CA1 stratum lacunosum-moleculare. This reinforces our previous conclusion that a structural remodelling of asymmetric ‘excitatory’ axo-spinous synapses occurs in this region of CA1 hippocampus following CRS