A "saddle-node" bifurcation scenario for birth or destruction of a Smale-Williams solenoid

Formation or destruction of hyperbolic chaotic attractor under parameter variation is considered with an example represented by Smale--Williams solenoid in stroboscopic Poincar\'{e} map of two alternately excited non-autonomous van der Pol oscillators. The transition occupies a narrow but finite parameter interval and progresses in such way that periodic orbits constituting a "skeleton" of the attractor undergo saddle-node bifurcation events involving partner orbits from the attractor and from a non-attracting invariant set, which forms together with its stable manifold a basin boundary of the attractor.Comment: 7 pages, 7 figures, 1 tabl

Study of the prevalence and severity of symptoms of postcovid syndrome

The aim of the study - to study the prevalence and severity of symptoms of postcovid syndrome in patients who underwent COVID-19 in 2020-2021 and factors affecting the severity of symptomsЦель исследования - изучить распространенность и 567 выраженность симптомов постковидного синдрома у пациентов, перенесших новую коронавирусную инфекцию в 2020-2021 гг. и факторы, влияющие на количество и выраженность симптомов этого синдром

Experience in Studying Herd and Individual Immunity to the SARS-CoV-2 Virus in Medical Workers

The aim was to study SARS-CoV-2 immunity among medical workers in Kazan.Materials and methods. Studied were serum samples from 348 medical workers from 10 medical organizations in Kazan, divided into groups according to the level of the alleged risk of infection of employees. To determine IgG, a two-stage direct version of the solid-phase ELISA and the test-system “SARS-CoV-2-IgG-ELISA-BEST” (Russia) were used.Results and discussion. At the time of the study and over the previous three months, the examined medical workers had no symptoms of acute respiratory viral infection or respiratory tract infections; there were negative results of examining nasopharyngeal/ oropharyngeal swabs for the presence of SARS-CoV-2 RNA. Seroprevalence for IgG to SARS-CoV-2 virus for different medical organizations in Kazan ranged within the scope of 3.3–30.8 % and averaged 16.4 %. The wide variation in seroprevalence values in medical workers of different medical organizations may indicate different levels of intensity of professional contacts and the effectiveness of anti-epidemic measures in these medical organizations. Among medical workers with seropositive results, the prevalence of persons with a very high coefficient of positivity (49.1 %) is observed, which characterizes high level of antiviral antibodies. The presence of a high proportion of seropositive individuals among medical workers, who have had an asymptomatic form of COVID-19 confirms the high intensity of the latent epidemic process, which must be taken into account when organizing preventive measures, including vaccination

Study of features of humoral immune response to the new coronavirus infection COVID-19 among healthcare workers

Relevance. Since the beginning of the epidemic in China, there have been reports of nosocomial cases of SARSCoV-2 infection, including among medical workers. Studies of the intensity of humoral immune response to the SARSCoV-2 virus among medical workers who are much more likely to have professional contact with COVID-19 patients than are of particular importance. The aim is to study the seroprevalence and features of the humoral immune response to SARS-CoV-2 among medical workers. Materials and methods. The study included 61 medical workers from a multidisciplinary hospital in Kazan, which was redesigned to provide medical care to patients with new coronavirus infection, using the method of random sampling. The control group consisted of 60 non-medical workers. For the determination of IgG, a solid-phase ELISA was used. Statistical processing of the results was carried out using MS Excel software. The error of the relative value (M±m) was calculated, and the 95% confidence interval of the frequency of occurrence. To assess the significance of differences, the Student’s test (t-test) was used for independent samples. Results. The proportion of those seropositive to SARS-CoV-2 in the study group was 45.9%, compared with 21.7% in the control group. Among medical workers seropositive to the SARS-CoV-2 virus, the proportion of asymptomatic forms was 18.5%, mild forms — 53.6%, moderate forms and severe forms 25%. Two forms of the formation of a humoral immune response among seropositive ones were revealed: the first is characterized by the gradual elimination of specific IgG antibodies to SARSCoV-2 after 8 weeks from the onset of the first symptoms of COVID-19, the second form is an increase in specific IgG to SARS-CoV-2 and a higher value of the coefficient level of IgM positivity to SARS-CoV-2 after 8–10 weeks from the onset of the first symptoms. The group of seropositive, “raising antibodies”, prevailed over the group of individuals “eliminating antibodies”. Among seropositive medical workers, two forms of the formation of a humoral immune response were revealed: synchronous with the parallel elimination of IgG and IgM antibodies and a parallel increase in IgG and IgM. Conclusion. The study of the level of humoral immunity to COVID-19 in medical workers is important in terms of planning both anti-epidemic measures and predicting the effectiveness of the response to vaccination to SARS-CoV-2

Эпидемиологические и клинические особенности миастении на территории Красноярского края

Aim. To study the epidemiological features of myasthenia gravis in the Krasnoyarsk region.Materials and methods. 314 cases of myasthenia gravis, registered by the Krasnoyarsk regional health information analytical center, 87 of these patients were under constant monitoring.Results. Mean age of the patients was 45.4 (SD 4.5) years. The number of women in the observed group – 66 (75.86 %), which was 3 times more than men – 21 (24.14 %). The prevalence was 10.98 per 100.000 population, the primary incidence – 0.01 by 1000.Conclusion. Clinical features of the disease in the region were established, the register of patients with myasthenia was formed. From September 2016 a department of the neuromuscular pathology on the basis of advice Regional Hospital was formed.Цель исследования – изучение эпидемиологических и клинических особенностей миастении на территории Красноярского края.Материалы и методы. Объектом исследования стали данные 314 пациентов с миастенией, зарегистрированные Красноярским краевым медицинским информационным аналитическим  центром. Из них 87 пациентов находились под постоянным динамическим наблюдением.Результаты. Средний возраст пациентов составил 45,4 года (стандартное отклонение 4,5 года). Число заболевших женщин – 66 (75,86 %), что в 3 раза больше, чем мужчин, – 21  (24,14 %). Распространенность составила 10,98 на 100 тыс. населения, первичная заболеваемость – 0,01 на 1000.Заключение. Установлены особенности клинического течения заболевания у пациентов, проживающих на территории Красноярского края, формируется краевой регистр больных. С  сентября 2016 г. открыт кабинет нервно-мышечной патологии на базе консультативной поликлиники Краевой клинической больницы

Микобактериозы легких: хирургические аспекты диагностики и лечения

Goal: to investigate efficiency of surgical diagnostics and treatment of pulmonary mycobacteriosis.Materials and methods: 31 patients diagnosed with pulmonary mycobacteriosis underwent surgery. Should mycobacteriosis be not diagnosed before the surgical intervention, the surgery was performed as per standard indications for fibrous cavernous pulmonary tuberculosis or tuberculoma.Results. There were 20 segmental resections, 4 lobectomies (with  МАС-, M. kansasii-infection), 5 pneumonectomies (with  M. xenopi and M. fortuitum-infection), 2 combined resections. The causative agent was isolated out of surgical specimens in 11 (35.4%) patients; in 10 patients (32.3%) mycobacteriosis was confirmed by detection of non-tuberculous mycobacteria in sputum or bronchial lavage along with the detection of the causative agent in the resected tissue. In the remaining 10 (32.3%) patients non-tuberculous mycobacteria were detected only in sputum and/or bronchial lavage before surgical interventions. Post-surgery complications were observed in 6 (19.4%) of patients, lethal outcome due to myocardial infarction. Clinical cure was achieved in 29 (93.6%) patients. Цель: изучение эффективности диагностики и лечения микобактериозов (МБ) легких с помощью хирургических методов.Материалы и методы. У 31 пациента с диагностированным МБ легких выполнены оперативные вмешательства. При не установленном до хирургического вмешательства МБ операцию выполняли по стандартным показаниям для фиброзно-кавернозного туберкулеза легких или туберкулемы.Результаты. Сегментарных резекций произведено 20, лобэктомий - 4 (при МАС-, M. kansasii-инфекции), пневмонэктомий - 5 (при M. xenopi и M. fortuitum-инфекции), комбинированных резекций - 2. У 11 (35,4%) возбудитель выделен только из операционного материала, еще у 10 (32,3%) больных диагноз МБ подтвержден обнаружением нетуберкулезных микобактерий (НТМБ) в мокроте и/или в бронхиальном смыве наряду с обнаружением возбудителя в резецированной ткани. У остальных 10 (32,3%) больных НТМБ выделены только из мокроты и/или промывных вод бронхов до проведения хирургического пособия. Осложнения после операций были у 6 (19,4%) больных, у 1 - летальный исход вследствие инфаркта миокарда. Клиническое излечение достигнуто у 29 (93,6%) больных

Natural Focality of Lyme Borreliosis, Granulocytic Anaplasmosis, and Monocytic Ehrlichiosis in Humans in the Republic of Tatarstan

Objective of the study is to investigate natural focality of Ixodidae tick borreliosis, granulocytic anaplasmosis, monocytic ehrli-chiosis in humans in the Republic of Tatarstan. Materials and methods. Utilized were the data from tick studies conducted between 2010–2015. Applying immune-enzymatic analysis, investigated were the blood sera from residents (donors) of Kazan and municipal districts of the Republic of Tatarstan for the presence of specific antibodies to borreliosis, ehrlichiosis, and anaplasmosis pathogens. Results and conclusions. For the first time ever, the data on spontaneous carriage of Ehrlichiosis pathogens in Ixodidae ticks have been obtained. The information received is an indicative of the active circulation of Borrelia, Ehrlichia and Anaplasma in the territory of the region and of necessity to expand the research on the “novel” for the Republic nosological forms of natural-focal infections

ДИАГНОСТИКА АНТИФОСФОЛИПИДНОГО СИНДРОМА У ЛИЦ С КЛИНИЧЕСКИМИ КРИТЕРИЯМИ ЗАБОЛЕВАНИЯ. ОПЫТ ОТДЕЛЬНОГО АМБУЛАТОРНОГО ЦЕНТРА

Antiphospholipid syndrome (APS) is an immune-mediated violation of coagulation, the diagnosis of which requires mandatory laboratory confirmation. Since the clinical manifestations of APS are extremely diverse, various specialists are involved in the diagnostic process – neurology, cardiologists, surgeons, hematologists, endocrinologists, laboratory medicine specialists, etc. So far, it remains an open question what specialist exactly should make the final diagnosis and supervise patient with APS. The experience of a separate diagnostic center shows the distribution of prescriptions and their compliance with the international recommendations. This study also provides data on the frequency of prescribing laboratory tests to confirm APS, which is 1.2% of all coagulation tests. Among the patients with suspected APS on the basis of clinical signs, only 12.2% of the diagnosis was confirmed. Presents the dangers of obtaining false-positive results that should be taken into account when prescribing laboratory tests.Антифосфолипидный синдром (АФС) – это иммуноопосредованное нарушение коагуляции, диагностика которого требует обязательного лабораторного подтверждения. Поскольку клинические проявления АФС крайне разнообразны, в процесс диагностики вовлекаются различные специалисты – неврологии, кардиологи, хирурги, гематологи, эндокринологи, врачи клинической лабораторной диагностики и др. До настоящего времени остается открытым вопрос, кто именно должен ставить окончательный диагноз и курировать пациента с АФС. Опыт отдельного диагностического центра показывает распределение назначений и их соответствие рекомендациям при участии в этом процессе врачей разных специальностей. В нашем исследовании представлены также данные о частоте назначения лабораторных тестов для подтверждения АФС, которая составляет 1,2% от всех коагуляционных тестов. Среди пациентов с подозрением на АФС на основании клинических признаков только у 12,2% был подтвержден диагноз. Представлены опасности получения ложноположительных результатов, которые должны быть учтены при назначении лабораторных исследований

Overview of Hantavirus Infections in the World, the Epidemiological Situation on Hemorrhagic Fever with Renal Syndrome in the Russian Federation in 2021, and Forecast for 2022

The paper presents a description of the epidemiological situation on Hantavirus infection incidence in the countries around the world. Comparative analysis of the intensity and dynamics of the epidemiological process of hemorrhagic fever with renal syndrome (HFRS) in the Russian Federation by Federal Districts in 2021 has been carried out and forecast of the HFRS incidence for 2022 prepared. The study has revealed that tense situation on incidence of hantavirus diseases was observed in the world in 2021. On the territory of the Russian Federation, there was a decrease in the HFRS incidence in 2021 (by 1.7 times compared to 2020). However, the results of epidemiological analysis of the HFRS incidence, epizootiological data and laboratory studies in certain Federal Districts of the Russian Federation indicate that the epidemiological situation on HFRS remains tense. High risk of HFRS infection is predicted in a number of regions of the country due to the favorable natural and climatic conditions in the winter period of 2021–2022 with a heavy snow cover, which contributed to the under-snow reproduction of small mammals, the main carriers of HFRS. The presence of infected rodents testifies to a high likelihood of complication of the epidemiological situation in areas of increased epidemic risk of HFRS

Антитела к рецептор-связывающему домену спайкового белка SARS-COV-2: связь с возрастом, пневмонией, длительностью периода после COVID-19

Despite the rapid accumulation of facts about the humoral immune response in COVID-19, there are still no evidencebased answers to questions about the factors influencing the level and duration of the detection period of antibodies to SARS-CoV-2 in the blood.Objective: To assess the prevalence, clinical and demographic associations of IgG antibodies to RBD of the SARSCoV-2 spike protein at different times after COVID-19.Materials and methods. Residents of the Altai region of Russia, Caucasians aged 20-93 years, who had COVID-19 from May 2020 to February 2021 (n = 314), took part in a onetime observational study. The level of antibodies in the blood was measured by enzyme-linked immunosorbent assay 1-14 months after the onset of the clinical manifestation of COVID-19.Results. Anti-RBD IgG antibodies of the SARS-CoV-2 spike protein were detected in 86.9% of the study participants. The dependence of the antibody titer on the duration of the period after COVID-19 was not revealed. The antibody titer was positively correlated with the complication of COVID-19 pneumonia and the volume of lung tissue lesions. The presence of pneumonia COVID-19 and the volume of lung tissue lesions are positively associated with age. Age positively correlated with antibody titer regardless of the pneumonia COVID-19 in the anamnesis.Conclusion. IgG antibodies to RBD of the SARS-CoV-2 spike protein are present in most of the COVID-19 patients. The titer of these antibodies in adults depends on age, complications of pneumonia COVID-19, and probably persists up to 14 months after the first symptoms of infection appear.Несмотря на быстрое накопление фактов о гуморальном иммунном ответе при COVID-19, пока нет доказательных ответов на вопросы о факторах, влияющих на уровень и длительность периода обнаружения антител к SARS-CoV-2 в крови.Цель: оценить распространенность наличия, клинические и демографические ассоциации антител IgG к RBD спайкового белка SARS-CoV-2 в разные сроки после COVID-19.Материалы и методы. В одномоментном обсервационном исследовании приняли участие жители Алтайского края России, европеоиды, в возрасте от 20 до 93 лет, переболевшие COVID-19 в период с мая 2020 г. по февраль 2021 г. (n=314). Уровень антител в крови измеряли через 1–14 месяцев от начала клинической манифестации COVID-19 методом иммуноферментного анализа.Результаты. Антитела IgG к RBD спайкового белка SARS-CoV-2 обнаружены у 86,9% участников исследования. Не выявлено зависимости титра антител от давности COVID-19. Титр антител положительно коррелировал с осложнением пневмонией COVID-19 и объемом поражений легочной ткани. Наличие пневмонии COVID-19 и объем поражений легочной ткани положительно связаны с возрастом. Возраст положительно коррелировал с титром антител независимо от наличия пневмонии COVID-19 в анамнезе.Заключение. Антитела IgG к RBD спайкового белка SARS-CoV-2 имеются у большей части переболевших COVID-19. Титр этих антител у взрослых зависит от возраста, осложнения пневмонией COVID-19 и может сохраняться до 14 месяцев после появления первых симптомов инфекции