Morphologic and functional correlates of synaptic pathology in the cathepsin D knockout mouse model of congenital neuronal ceroid lipofuscinosis

Mutations in the cathepsin D (CTSD) gene cause an aggressive neurodegenerative disease (congenital neuronal ceroid lipofuscinosis) that leads to early death. Recent evidence suggests that presynaptic abnormalities play a major role in the pathogenesis of CTSD deficiencies. To identify the early events that lead to synaptic alterations, we investigated synaptic ultrastructure and function in pre-symptomatic CTSD knock-out (Ctsd(−/−)) mice. Electron microscopy revealed that there were significantly greater numbers of readily releasable synaptic vesicles present in Ctsd(−/−) mice than in wild-type control mice as early as postnatal day 16. The size of this synaptic vesicle pool continued to increase with disease progression in the hippocampus and thalamus of the Ctsd(−/−) mice. Electrophysiology revealed a markedly decreased frequency of miniature excitatory postsynaptic currents (EPSCs) with no effect on pair-pulse modulation of the evoked EPSPs in the hippocampus of Ctsd(−/−) mice. The reduced miniature EPSC frequency was observed before the appearance of epilepsy or any morphological sign of synaptic degeneration. Taken together, the data indicate that CTSD is required for normal synaptic function, and that a failure in synaptic trafficking or recycling may be an early and important pathological mechanism in Ctsd(−/−) mice; these presynaptic abnormalities may initiate synaptic degeneration in advance of subsequent neuronal loss

δ15N in Birch and Pine Leaves in the Vicinity of a Large Copper Smelter Indicating a Change in the Conditions of Their Soil Nutrition

δ13C and δ15N were analyzed in the leaves of Pinus sylvestris L. and Betula spp. under the conditions of severe heavy metal (Zn, Cu, Cd, and Pb) contamination. Twenty-seven plots located near the Karabash copper smelter (Russia) were studied. No reliable correlation of 13C in tree leaves with the level of pollution was observed. δ15N, both in Pinus sylvestris and Betula spp., increased similarly in polluted areas. δ15N was increased by 2.3‰ in the needles of Pinus sylvestris and by 1.6‰ in the leaves of Betula spp. in polluted plots compared to the background ones. The probable reasons for the increase in δ15N were estimated using multiple regression. The regression model, which includes two predictors: δ15N in the humus horizon and the occurrence of roots in the litter, explains 33% of the total variability of δ15N in leaves. Thus, in ecosystems polluted with heavy metals, the state of trees is determined not only by the direct toxic effects of heavy metals but also by indirect ones associated with the features of plant mineral nutrition. This fact opens the way to the search for opportunities to control the state of plants in disturbed ecosystems by regulating the content of mineral nutrition elements. © 2022 by the authors

Assessment of Resistance in <i>Burkholderia pseudomallei</i> to Benzalkonium Chloride and Antibiotics

The aim of the study was to investigate the features of resistance formation in Burkholderia pseudomallei to quaternary ammonium compounds, as well as to analyze its influence on the development of antibiotic resistance.Materials and methods. 10 strains of melioidosis causative agent with typical cultural and morphological properties have been studied. The selection of variants resistant to benzalkonium chloride was carried out by successive passages on a dense nutrient medium with the addition of a disinfectant in increasing concentrations. The determination of sensitivity to benzalkonium chloride was performed through serial dilutions in agar, to antibacterial drugs from the groups of sulfonamides, β-lactams and tetracyclines – using disk diffusion method. Statistical processing of the obtained results was conducted with the help of the Microsoft Excel 2019 software. Arithmetic mean values and errors of mean values were calculated. The significance of differences between the parameters was determined applying Student’s t-test.Results and discussion. All parental strains showed a similar degree of resistance to the disinfectant compound and most of the strains – susceptibility to the antibiotics tested. Cultivation of B. pseudomallei strains on a nutrient medium with the addition of benzalkonium chloride led to an increase in resistance to this disinfectant. In addition, an increase in the level of resistance to all studied antibiotics was found. Statistical processing of the data collected revealed a significant correlation between the change in sensitivity to benzalkonium chloride and the emergence of resistance to amoxicillin/ clavulanic acid and ceftazidime. It was found that the causative agent of melioidosis, with a natural high susceptibility to benzalkonium chloride, has a high potential for developing resistance to this disinfectant compound, which is of practical importance in the development of disinfection regimens using quarternary ammonium compounds. For the first time, a direct correlation between a decrease in the sensitivity to benzalkonium chloride in B. pseudomallei and emergence of resistance to amoxicillin/clavulonic acid and ceftazidime has been demonstrated

Potent antiviral activity against HSV-1 and SARS-CoV-2 by antimicrobial peptoids

Viral infections, such as those caused by Herpes Simplex Virus-1 (HSV-1) and SARS-CoV-2, affect millions of people each year. However, there are few antiviral drugs that can effectively treat these infections. The standard approach in the development of antiviral drugs involves the identification of a unique viral target, followed by the design of an agent that addresses that target. Antimicrobial peptides (AMPs) represent a novel source of potential antiviral drugs. AMPs have been shown to inactivate numerous different enveloped viruses through the disruption of their viral envelopes. However, the clinical development of AMPs as antimicrobial therapeutics has been hampered by a number of factors, especially their enzymatically labile structure as peptides. We have examined the antiviral potential of peptoid mimics of AMPs (sequence-specific N-substituted glycine oligomers). These peptoids have the distinct advantage of being insensitive to proteases, and also exhibit increased bioavailability and stability. Our results demonstrate that several peptoids exhibit potent in vitro antiviral activity against both HSV-1 and SARS-CoV-2 when incubated prior to infection. In other words, they have a direct effect on the viral structure, which appears to render the viral particles non-infective. Visualization by cryo-EM shows viral envelope disruption similar to what has been observed with AMP activity against other viruses. Furthermore, we observed no cytotoxicity against primary cultures of oral epithelial cells. These results suggest a common or biomimetic mechanism, possibly due to the differences between the phospholipid head group makeup of viral envelopes and host cell membranes, thus underscoring the potential of this class of molecules as safe and effective broad-spectrum antiviral agents. We discuss how and why differing molecular features between 10 peptoid candidates may affect both antiviral activity and selectivity

Tonically Active α2 Subunit-Containing Glycine Receptors Regulate the Excitability of Striatal Medium Spiny Neurons

Medium spiny neurons (MSNs) of the dorsal striatum represent the first relay of cortico-striato-thalamic loop, responsible for the initiation of voluntary movements and motor learning. GABAergic transmission exerts the main inhibitory control of MSNs. However, MSNs also express chloride-permeable glycine receptors (GlyRs) although their subunit composition and functional significance in the striatum is unknown. Here, we studied the function of GlyRs in MSNs of young adult mice. We show that MSNs express functional GlyRs, with α2 being the main agonist binding subunit. These receptors are extrasynaptic and depolarizing at resting state. The pharmacological inhibition of GlyRs, as well as inactivation of the GlyR α2 subunit gene hyperpolarize the membrane potential of MSNs and increase their action potential firing offset. Mice lacking GlyR α2 showed impaired motor memory consolidation without any changes in the initial motor performance. Taken together, these results demonstrate that tonically active GlyRs regulate the firing properties of MSNs and may thus affect the function of basal ganglia

Competence of mosquitoes <i>Culex pipiens f.</i> molestus as carriers of West Nile virus under various temperature conditions

Introduction. The Culex pipiens mosquito is one of the proven vectors of the West Nile virus (WNV). Culex pipiens f. molestus (Cx. p. f. molestus) is a synanthropic, autogenous, widespread form of the species that can feed on a broad range of hosts, including humans. The temperature of the habitat of insects affects the potential for virus transmission, which determines the likelihood of them carrying the pathogen of West Nile fever. The goal is an experimental study of the temperature of the habitat of larvae on the competence of mosquitoes Cx. p. f. molestus as carriers of WNV. Materials and methods. We used a strain of the WNV (WNV_Volg601/18 genotype 2) and a laboratory culture of mosquitoes Cx. p. f. molestus. The concentration of the virus was detected by plaque formation using Vero cells. Insects were infected orally at the larval stage, with subsequent incubation at 20, 22 or 28C. 72 hours after the emergence of all adults from the pupae, the mosquitoes were immobilized by cold, the sex of imago was determined, the salivary glands were isolated from the females, and the presence of WNV in glandes and its titer were detected. Results. The titer of WNV sufficient to transmit the pathogen through the insect biting was observed in the salivary glands of insects kept at a temperature of 22 and 28C, with the virus titer rising with the temperature increasing. No virus was detected in the salivary glands of female insects kept at a temperature of 20C. Conclusion. Thus, it appears that the habitat temperature is an important factor limiting the replication and content of WNV in the salivary glands of Cx. p. f. molestus

Морфофункциональная характеристика гиппокампа белых крыс в остром периоде после тяжелой черепно-мозговой травмы на фоне применения L-лизина эсцината

Aim of study. The study is devoted to the effect of L-lysine aescinat on the nervous tissue of the CA1 and CA3 fields of the hippocampus of the brain of white rats in the acute period after severe traumatic brain injury (TBI).Material and methods. TBI was simulated by applying a blow to the parieto-occipital region with a freely falling weight weighing 200-250 grams from a height of 50 cm using a special rail rack. The objectives of the study were: 1) comparative morphometric assessment of the degree of hydration, cyto- and glioarchitectonics of different layers of CA1 and CA3 fields after ischemia without treatment; 2) the effect of L-lysine aescinat on these indicators. We used histological (staining of sections with hematoxylin-eosin and Nissl), immunohistochemical (for NSE, MAP-2 and GFAP) and morphometric methods. On thin (4 μm) serial frontal sections of the hippocampus, neurons, astrocytes, microvessels and neuropiles were studied in control (intact animals, n=5) and 1 and 3 days after injury without treatment (n=10, comparison group) and with treatment ( n = 10, main group). The number density of neurons was determined using the Nissl staining of cells and by the reaction to NSE. The cytoskeleton of neurons was studied by detecting MAP-2, and astroglia by GFAP. On color raster images (staining with hematoxylin and eosin, x100) using the Find Maxima plug-in filter, the zones of maximum brightness were determined, which were then analyzed using Analyze Particles from the ImageJ 1.52s program. Zones of maximum brightness corresponded to areas of the hippocampus with a high degree of hydration of the nervous tissue - edema-swelling. The nature of the distribution, statistical hypotheses, and plotting were checked using Statistica 8.0 software and R environment.Results. In control animals, normochromic neurons without signs of changes in the cytoskeleton prevailed in all layers of fields CA1 and CA3, and a low degree of hydration of the nervous tissue was noted (the relative proportion of zones of maximum brightness was 5–8%). One and 3 days after TBI, there was a statistically significant increase in the focal content of dystrophic and necrobiotically altered neurons (95% confidence interval: 52–78%), manifestations of reactive gliosis were noted, and the proportion of zones of maximum brightness increased to 16%. Statistically significant layer-by-layer differences were revealed between the CA1 and CA3 fields of the hippocampus. The use of L-lysine aescinat had a statistically significant effect on the morphometric parameters of the nervous tissue of the hippocampus.Conclusion. In the early post-traumatic period after TBI, the degree of hydration of the nervous tissue of the hippocampus increased. Heteromorphicity of dystrophic and necrobiotic changes in different layers of CA1 and CA3 fields was noted. L-lysine aescinate had a statistically significant positive effect on these changes. To a greater extent, this is typical for the CA3 field. The revealed changes are considered not only as patho-, but also as sanogenetic structural mechanisms of protection and reorganization of the hippocampus in the acute post-traumatic period.1. In the acute period (1−3 days) after severe traumatic brain injury, the degree of hydration of all components of the hippocampal nervous tissue increased. In the group without treatment, 3 days after injury, the relative volume of edema-swelling zones varied from 10 to 13% in CA1 (control 3-7%) and from 8 to 16% in CA3 (control 5–10%).2. The heteromorphism of hydropic changes in the molecular layer, the layer of pyramidal neurons and the polymorphic layer was established. The maximum increase in the volume of free water (more than twofold) was characteristic of the molecular and polymorphic layer CA1, as well as the polymorphic layer CA3.3. The use of L-lysine aescinat in the acute period significantly changed the manifestations of hydropic dystrophy. One day after injury, the volume of free water increased in comparison with animals without treatment, and then, after 3 days, decreased, but remained higher than in the comparison group. The maximum effect of the drug was noted in field CA3.Цель исследования. Исследование посвящено изучению влияния L-лизина эсцината на нервную ткань полей СА1 и СА3 гиппокампа головного мозга белых крыс (Wistar) в остром периоде после тяжелой черепно- мозговой травмы (ТЧМТ).Материал и методы. ТЧМТ моделировали нанесением на теменно-затылочную область удара свободно падающим грузом массой 200−250 г с высоты 50 см с помощью специальной рельсовой стойки. Задачами исследования были: 1) сравнительная морфометрическая оценка степени гидратации, цито- и глиоархитектоники различных слоев полей СА1 и СА3 после ТЧМТ без лечения; 2) влияние на эти показатели L-лизина эсцината. Использованы гистологические (окраска срезов гематоксилином- эозином и по Нисслю), иммуногистохимические (на NSE, MAP-2 и GFAP) и морфометрические методы. На тонких (4 мкм) серийных фронтальных срезах гиппокампа изучены нейроны, астроциты, микрососуды и нейропиль в контроле (интактные животные, n=5) и через 1 и 3 суток после травмы без лечения (n=10, группа сравнения) и с лечением (n=10, основная группа). Численную плотность нейронов определяли с помощью окраски клеток по Нисслю и реакции на NSE. Цитоскелет нейронов изучали с помощью реакции на МАР-2, а астроглии — GFAP. На цветных растровых изображениях (окраска гематоксилином и эозином, объектив х100) с помощью плагин-фильтра “Find Maxima” определяли зоны максимальной яркости (ЗМЯ), которые затем анализировали с помощью “Analyze Particles” из программы ImageJ 1.52s. ЗМЯ соответствовали участкам гиппокампа с высокой степенью гидратации нервной ткани — отек-набухание. Характер распределения, статистические гипотезы, построение графиков проверяли с помощью программ Statistica 8.0 и среды R.Результаты. У контрольных животных во всех слоях полей СА1 и СА3 превалировали нормохромные нейроны без признаков изменения цитоскелета, отмечена низкая степень гидратации нервной ткани (относительная доля ЗМЯ 5−8%). Через 1 и 3 суток после ТЧМТ статистически значимо увеличивалось очаговое содержание дистрофически и некробиотически измененных нейронов (95% доверительный интервал: 52−78%), отмечались проявления реактивного глиоза, а доля ЗМЯ увеличивалась до 16%. Выявлены статистически значимые послойные различия между полями СА1 и СА3 гиппокампа. Применение L-лизина эсцината оказывало статистически значимое влияние на морфометрические показатели нервной ткани гиппокампа.Заключение. В раннем периоде после ТЧМТ увеличивалась степень гидратации нервной ткани гиппокампа. Отмечена гетероморфность дистрофических и некробиотических изменений в разных слоях полей СА1 и СА3. L-лизин эсцинат статистически значимо влиял на эти изменения. В большей степени это характерно для поля СА3. Выявленные изменения рассматриваются не только как пато-, но и как саногенетические структурные механизмы защиты и реорганизации гиппокампа в посттравматическом периоде.Выводы.1. В остром периоде (1−3 суток) после тяжелой черепно-мозговой травмы увеличивалась степень гидратации всех компонентов нервной ткани гиппокампа. В группе без лечения через 3 суток после травмы относительный объем зон отека-набухания варьировался от 10 до 13% в СА1 (контроль 3−7%) и от 8 до 16% — в СА3 (контроль 5−10%).2. Установлена гетероморфность гидропических изменений в молекулярном слое, слое пирамидных нейронов и полиморфном слое. Максимальное увеличение объема свободной воды (более чем в 2 раза) было характерно для молекулярного и полиморфного слоя СА1, а также полиморфного слоя СА3.3. Применение в остром периоде L-лизина эсцината способствовало статистически значимому изменению проявлений гидропической дистрофии. Через 1 сутки после травмы объем свободной воды увеличивался в сравнении с животными без лечения, а затем, спустя 3 суток, уменьшался, но оставался выше, чем в группе сравнения. Максимальное влияние препарата отмечено в поле СА3