Enhanced antibacterial activity of silver nanoparticles/halloysite nanotubes/graphene nanocomposites with sandwich-like structure

A sandwich-like antibacterial reagent (Ag/HNTs/rGO) was constructed through the direct growth of silver nanoparticles on the surface graphene-based HNTs nanosheets. Herein, various nanomaterials were combined by adhesion effect of DOPA after self-polymerization. Ag/HNTs/rGO posses enhanced antibacterial ability against E. coli and S. aureus compared with individual silver nanoparticles, rGO nanosheets or their nanocomposites

Multi-response analysis in the material characterisation of electrospun poly (lactic acid)/halloysite nanotube composite fibres based on Taguchi design of experiments: fibre diameter, non-intercalation and nucleation effects

Poly (lactic acid) (PLA)/halloysite nanotube (HNT) composite fibres were prepared by using a simple and versatile electrospinning technique. The systematic approach via Taguchi design of experiments (DoE) was implemented to investigate factorial effects of applied voltage, feed rate of solution, collector distance and HNT concentration on the fibre diameter, HNT non-intercalation and nucleation effects. The HNT intercalation level, composite fibre morphology, their associated fibre diameter and thermal properties were evaluated by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), imaging analysis and differential scanning calorimetry (DSC), respectively. HNT non-intercalation phenomenon appears to be manifested as reflected by the minimal shift of XRD peaks for all electrospun PLA/HNT composite fibres. The smaller-fibre-diameter characteristic was found to be sequentially associated with the feed rate of solution, collector distance and applied voltage. The glass transition temperature (T g) and melting temperature (T m) are not highly affected by varying the material and electrospinning parameters. However, as the indicator of the nucleation effect, the crystallisation temperature (T c) of PLA/HNT composite fibres is predominantly impacted by HNT concentration and applied voltage. It is evident that HNT’s nucleating agent role is confirmed when embedded with HNTs to accelerate the cold crystallisation of composite fibres. Taguchi DoE method has been found to be an effective approach to statistically optimise critical parameters used in electrospinning in order to effectively tailor the resulting physical features and thermal properties of PLA/HNT composite fibres

МР-МОРФОМЕТРИЯ И ДИФФУЗИОННО-ТЕНЗОРНАЯ МРТ В ОЦЕНКЕ ИЗМЕНЕНИЙ МОЗОЛИСТОГО ТЕЛА У ДЕТЕЙ СО СПАСТИЧЕСКОЙ ДИПЛЕГИЕЙ

The aim of the study was to compare the volumes according to MR morphometry and diffusion values according to diffusion-tensor MRI (DT-MRI) of the corpus callosum in children with spastic diplegia. Methods: the main group consisted of 12 children aged from 1 year 8 months to 4 years 3 months, the comparison group — 5 children with normal motor development, who did not have motor impairments, at the age from 1 year and 3 months up to 3 years 8 months. All patients underwent MR-morphometry, DTI. A comparison was made between the volumes and diffusion values of the corpus callosum between groups. Results: Significant differences were found (p<0,05) in the volume of the genu, splenium and the middle third of the trunk of the corpus callosum. Significant differences (p<0,05) of diffusion values in the middle and posterior third of the trunk of the corpus callosum were also revealed. The data obtained demonstrate the diffuse nature of pathological changes in the corpus callosum in children with spastic diplegia.Целью исследования являлась сравнительная оценка объема мозолистого тела по данным МР-морфометрии и показателей диффузии в мозолистом теле по данным диффузионно-тензорной МРТ (ДТ-МРТ) у детей со спастической диплегией. Методы: основную группу составили 12 детей в возрасте от 1 года 8 мес до 4 лет 3 мес, группу сравнения — 5 детей с нормальным моторным развитием, не имевших двигательных нарушений, в возрасте от 1 года 3 мес до 3 лет 8 мес. Обследуемым выполнялась МР-морфометрия, диффузионно-тензорная МРТ. Проводилось сравнение объемов мозолистого тела и показателей диффузии между группами. Результаты: выявлены достоверные различия (p<0,05) в объеме колена, валика и средней трети ствола мозолистого тела. Также выявлены достоверные различия (p<0,05) показателей диффузии в средней и задней трети ствола, валике мозолистого тела. Полученные данные демонстрируют диффузный характер патологических изменений в мозолистом теле у детей со спастической диплегией

Особенности этиологической структуры ОРВИ в отдельных возрастных и профессиональных группах населения Санкт-Петербурга в эпидемический сезон 2013-2014 гг .

The objective. To study etiological structure of acute respiratory viral diseases in the hospitalized patients of different age groups and to reveal their peculiarities in children and adults, as well as in adults of draft age (18–26 years) among civilians and military recruits.Materials and methods. 2202 in patients with acute respiratory diseases of moderate and severe degree, including 1123 patients (51.0%) aged up to 18 years and 1079 patients (49,0%) aged 18 years and above, were examined during the epidemic season since September 2013 till July 2014. RNA or DNA of influenza A(H1N1)pdm09 and A(H3N2), influenza B, types 1–4parainfluenza, adenoviruses, respiratory syncytial virus, rino-, metapneumo-, corona-, entero- and boca- viruses were determinedin nasopharyngeal swabs, sputum and brohchoalveolar lavage by real time PCR method. Significance of differences (p<0,05) in cases incidence of compared independent groups were assessed by the Pearson,s χ2 (chi-squared) test.Results. Genetic material of viruses causing ARD was revealed in 1343 cases (61,0%). Influenza viruses A and B (30,3%), RS viruses (23,6%), rinoviruses (22,8%) and adenoviruses (12,5%) prevail among ARD viral pathogens. The parainfluenza virus infection was laboratory confirmed in 8,7%, coronavirus – in 4,4%, bocavirus – in 1,2%, enterovirus – in 0,7% of cases. Assessment of age-related features of ARD etiologic structure showed that RS virus (37,6%, p<0,05) and parainfluenza virus (11,3%, p<0,05) infections were registered significantly often among children. Influenza viruses (46,4%, p<0,05), adenovirus (26,3%, p<0,05) and rinovirus (25,7%, p<0,05) were verified significantly often among adults. Etiologic ARD structure of military personnel 18–26 years old was characterized by significant prevalence of adenovirus infection (53,9%, p<0,05).Conclusion. The study has shown that acute respiratory diseases caused by RS and parainfluenza viruses predominated among children, by influenza viruses – among adults (civilians) and by adenovirus – among military personnel.Цель. Исследовать этиологическую структуру острых респираторных вирусных заболеваний у госпитализированных больных в разных возрастных и профессиональных группах и выявить ее особенности у детей и взрослых, а также у взрослых призывного возраста (18– 26 лет) из числа гражданских лиц и военнослужащих.Материалы и методы. В эпидемический сезон с сентября 2013 г. по июль 2014 г. обследовано 2202 стационарных больных острыми респираторными заболеваниями средней и тяжелой степенями тяжести, в том числе в возрасте до 18 лет – 1123 пациента (51,0%), 18 лет и старше – 1079 пациентов (49,0%). РНК или ДНК вирусов гриппа А(H1N1)pdm09 и А(H3N2), гриппа В, парагриппа 1–4 типов, аденовирусов, респираторно-синцитиального вируса, рино-, метапневмо-, корона-, бока- и энтеровирусов определяли в носоглоточных смывах, мокроте и бронхоальвеолярном лаваже методом ПЦР. Достоверность различия (p<0,05) частоты встречаемости случаев в сравниваемых независимых группах оценивали по критерию χ2 (хи-квадрат) Пирсена.Результаты. При обследовании больных генетический материал вирусов, вызывающих ОРЗ, выявлен в 1343 случаях (61,0%). Среди респираторных вирусов в качестве возбудителей ОРЗ доминируют вирусы гриппа А и В (30,3%), РС-вирусы (23,6%), риновирусы (22,8%) и аденовирусы (12,5%). Парагриппозная инфекция установлена в 8,7%, коронавирусная – в 4,4%, бокавирусная – в 1,2%, энтеровирусная – в 0,7% случаев. При оценке возрастных особенностей этиологической структуры ОРЗ выявлено, что среди детей достоверно чаще регистрировали РС-вирусную (37,6%, p<0,05) и парагриппозную (11,3%, p<0,05) инфекции. У взрослых достоверно чаще верифицировали грипп (46,4%, p<0,05), аденовирусную (26,3%, p<0,05) и риновирусную (25,7%, p<0,05) инфекции. Особенностью этиологической структуры ОРЗ у военнослужащих в возрасте 18–26 лет является достоверное преобладание аденовирусной инфекции (53,9%, p<0,05).Заключение. Исследование показало, что в структуре ОРЗ среди детей достоверно чаще регистрируют РС-вирусные заболевания и парагрипп, среди взрослых –грипп (у гражданских лиц) и аденовирусную инфекцию (у военнослужащих)

Течение генерализованной формы менингококковой инфекции у пациента призывного возраста, отказавшегося от специфической профилактики (клинический случай)

Meningococcal infection is an acute infectious disease caused by Neisseria meningitidis, characterized by a polymorphism of clinical manifestations from meningococcus carriage to invasive forms. They, in turn, pose a great danger to the patient’s life, since in most cases they have a severe course with the development of complications, fulminant course and high mortality. The success of treatment of invasive meningococcal disease largely depends on the timeliness of diagnosis and the timing of treatment initiation. The article describes a clinical case of a generalized form of severe meningococcal infection with a rapidly developing infectious toxic shock, disseminated intravascular coagulation syndrome in a soldier who had previously refused specific prophylaxis. Despite the mistakes made at the prehospital stage and, accordingly, late hospitalization, this case had a favorable outcome.Менингококковая инфекция — острое инфекционное заболевание, вызываемое Neisseria meningitidis, характеризующееся полиморфизмом клинических проявлений от менингококконосительства до генерализованной формы. Она, в свою очередь, представляет большую опасность для жизни заболевшего, поскольку в большинстве случаев имеет  молниеносное течение с развитием осложнений и высокую летальность. Успех терапии генерализованных форм менингококковой инфекции во многом зависит от своевременности диагностики и срока начала лечения. В статье описан клинический случай генерализованной формы менингококковой инфекции тяжелой степени тяжести со  стремительно развившимся инфекционно-токсическим шоком, синдромом диссеминированного внутрисосудистого свертывания у военнослужащего по призыву, отказавшегося ранее от специфической профилактики. Несмотря на допущенные ошибки на догоспитальном этапе и, соответственно, позднюю госпитализацию, данный случай имел благоприятный исход

Electron beam stimulated formation of CdS nanoparticles within calixarene Langmuir-Blodgett films

Two possible types of cadmium sulphide (CdS) nanostructures can be formed within Langmuir-Blodgett (LB) films of calixarene Cd salt as a result of exposure to H2S gas: nanoclusters with the size of about 1.5 nm or two-dimensional planes with the thickness of about 1.7 nm. Transmission electron microscopy and electron diffraction studies on calixarene/CdS LB films show that CdS particles are not present in the fresh samples at the beginning, but they are gradually formed under exposure to a high energy electron beam. A blueshift of the first exciton absorption band and an increase of the extinction coefficient, caused by exposure to H2S gas, were found with UV-visible optical spectroscopy and surface plasmon resonance, respectively. (C) 2000 American Institute of Physics. [S0021- 8979(00)07015-8]

STRUCTURAL FEATURES OF SELECTIVE AND NONSELECTIVE NOD RECEPTOR AGONISTS

Muramyl peptides are fragments of bacterial peptidoglycan playing an important role in the activation of innate immune system. Core structure of muramyl peptides is composed of N-acetylmuramic acid residue (MurNAc) covalently bound to a peptide consisting of 2-5 amino acid residues. The first residue in the peptide chain is usually L-alanine, the 2nd is D-isoglutamine or D-isoglutamic acid, the 4th and 5th are D-alanines. The 3rd residue is most variable being represented by L-lysine or L-ornithine in Gram-positive bacteria, or by meso-diaminopimelic acid (meso-DAP) in Gram-negative bacteria. Muramyl peptides are potential immunostimulants and adjuvants. Two receptors, NOD1 and NOD2, are known to play a central role in muramyl peptide recognition. However, the data on NOD receptor specificity for several common muramyl peptides are not available or incomplete.The goal of this study was to extend knowledge on possible relationships between structure of natural, or chemically modified muramyl peptides, and their selectivity towards NOD1 and NOD2 receptors.We investigated ability of natural muramyl peptides and their derivatives to activate NOD1 and NOD2. To this end, we used a novel biological test system, which represents modified HEK293T cells with NF-κB-driven reporter gene (luciferase) expression and knock-outs of endogenous NOD1 and/or NOD2 genes. As a result, we have shown that NOD2 has a broader spectrum of natural agonists than previously thought. In particular, NOD2 recognizes muramyl peptides from Gram-negative bacteria containing a meso-DAP residue, which have been considered inactive towards NOD2. NOD1 recognizes only muramyl peptides containing a mesoDAP residue; however, this molecule should not be exposed as a terminal residue, as thought earlier, but it may also be present within the peptide chain. This data imply that natural muramyl peptides containing mesoDAP have a dual receptor specificity (NOD1 and NOD2), i.e. they are non-selective NOD receptor agonists.Destruction of the MurNAc residue eliminates ability of these muramyl peptides to activate NOD2, but has no effect on their NOD1 agonism. Hence, modified muramyl peptides containing meso-DAP and a destroyed MurNAc residue are selective NOD1 agonists. Natural muramyl peptides featuring an intact MurNAc and no meso-DAP are selective NOD2 agonists.Conclusions: 1) we have characterized key structural features of selective NOD1 and NOD2 agonists as well as non-selective NOD receptors agonists; 2) we show the importance of these new data for understanding innate immune response regulation, and for development of novel muramyl peptide immunostimulants