Sex hormones in female residents of Yamal-Nenets autonomous district depending on the fertility status

Severe climatic conditions adversely affect the human reproductive function; there is evidence of earlier aging of the endocrine system in residents of the northern territories. However, there is insufficient data on the content of androgens and estrogens in postmenopausal women of the North. This determined the aim of the work - to study the characteristics of the content of sex hormones in fertile and postmenopausal women in the Arctic zone of the Russian Federation. Material and methods. In the period of increasing daylight hours, there were examined 60 residents of the Yamal-Nenets Autonomous District of the reproductive (n = 33) and postmenopausal (n = 27) periods. The serum luteinizing, follicle-stimulating hormones, progesterone, dehydroepiandrosterone sulfate, dihydrotestosterone, androstenedione, total and free fractions of testosterone, estrogen, estrone, sex-hormone-binding globulin were determined by immunoassay analysis using sets of «Khema-Medica» (Russia), Alkor-Bio (Russia), DRG (Germany). The research results were statistically processed using application software package STATISTIC 10.0. Results. There were shown high median values of progesterone (2.41 nmol/L) and dihydrotestosterone (191.02 pg/ml) in postmenopausal women, as well as increased concentrations of sex-hormone-binding globulin in both fertile (170.66 nmol/L) and postmenopausal (154.84 nmol/L) women. At the same time, free testosterone levels are slightly reduced, especially in postmenopausal women (0.50 pg/ml). Conclusion. The revealed features of the hormonal profile of women living in high latitudes may be an unfavorable factor for the development of various metabolic disorders

Interparticle correlations in the simple cubic lattice of ferroparticles: Theory and computer simulations

Anisotropic interparticle correlations in the simple cubic lattice of single-domain ferroparticles (SCLF) are studied using both theory and computer simulation. The theory is based on the Helmholtz free energy expansion like classical virial series up to the second virial coefficient. The analytical formula for the Helmholtz free energy is incorporated in a logarithmic form to minimize the effects of series truncation. The new theoretical approach, including discrete summation over lattice nodes coordinates, is compared critically against the classical virial expansion of the Helmholtz free energy for the dipolar hard sphere fluid; the main differences between the Helmholtz free energy of SCLF and dipolar hard sphere fluid are discussed. The theoretical results for the Helmholtz free energy, the magnetization, and the initial magnetic susceptibility of the SCLF are compared against Molecular Dynamic simulation data. In all cases, theoretical predictions using logarithmic form of the Helmholtz free energy are seen to be superior, but they only have an applicability range of the effective dipolar coupling constant λe<1.5. For highest values of λe, the structural transition of the magnetic dipoles in SCLF is observed in Molecular Dynamic simulation. It has been shown that for λe≳2, an antiferromagnetic order appears in the system. © 2020The reported study was funded by RFBR , project number 20-02-00358 . AYS and EAE acknowledged Prof. Philip Camp for his advice and useful discussions

Behavior of Bulky Ferrofluids in the Diluted Low-Coupling Regime: Theory and Simulation

A theoretical formalism to predict the structure factors observed in dipolar soft-sphere fluids based on a virial expansion of the radial distribution function is presented. The theory is able to account for cases with and without externally applied magnetic fields. A thorough comparison of the theoretical results to molecular-dynamics simulations shows a good agreement between theory and numerical simulations when the fraction of particles involved in clustering is low; i.e., the dipolar coupling parameter is λ 2, and the volume fraction is φ 0.25. When magnetic fields are applied to the system, special attention is paid to the study of the anisotropy of the structure factor. The theory reasonably accounts for the structure factors when the Langevin parameter is smaller than 5. © 2010 The American Physical Society.This research has been carried out within the financial support of RFBR Grant No. 08-02-00647 and DFG-RFBR Joint Grants No. HO 1108/12-1 and No. 06-02-04019

The influence of interparticle correlations and self-assembly on the dynamic initial magnetic susceptibility spectra of ferrofluids

Using computer simulations and a mean-field theoretical approach, we study how the growth in dipolar interparticle correlations manifests itself in the frequency-dependent initial magnetic susceptibility of a ferrofluid. Our recently developed theory gives the correct single-particle Debye-theory results in the low-concentration, non-interacting regime; and it yields the exact leading-order contributions from interparticle correlations. The susceptibility spectra are analysed in terms of the low-frequency behaviours of the real and imaginary parts, and the position of the peak in the imaginary part. By comparing the theoretical predictions to the results from Brownian dynamics simulations, it is possible to identify the conditions where correlations are important, but where self-assembly has not developed. We also provide a qualitative explanation for the behaviour of spectra beyond the mean-field limit. © 2016 Elsevier B.V

Structure factor of model bidisperse ferrofluids with relatively weak interparticle interactions

In the present manuscript we develop a theoretical approach to describe the pair correlation function of bidisperse magnetic dipolar hard- and soft-spheres. We choose bidisperse system as the first step to allow for polydispersity when studying thermodynamics of magnetic fluids. Using diagram technique we calculate the virial expansion of the pair correlation function up to the first order in density and fourth order in the dipolar strength. Even though, the radial distribution functions are extremely sensitive to the steric potential, we show that the behaviour of the isotropic centre-centre structure factor is almost indifferent to the type of the short-range repulsion. We extensively compare our theoretical results to the data of molecular dynamics simulations, which helps us to understand the range of validity of the virial expansion both on density and magnetic dipolar strength. We also investigate the influence of the granulometric composition on the height, width, and position of the structure factor first peak in order to clarify whether it is possible to extract structural information from experimentally measured small angle neutron scattering intensities. © 2013 AIP Publishing LLC

Computer Simulations of Dynamic Response of Ferrofluids on an Alternating Magnetic Field with High Amplitude

The response of ferrofluids to a high-amplitude AC magnetic field is important for several applications including magnetic hyperthermia and biodetection. In computer simulations of the dynamic susceptibility of a ferrofluid outside the linear response region, there are several problems associated with the fact that an increase in the frequency of the AC field leads to the appearance of additional computational errors, which can even lead to unphysical results. In this article, we study the dependence of the computational error arising in the computer simulation of the dynamic susceptibility on the input parameters of the numerical algorithm: the length of the time step, the total number of computer simulation periods, and averaging period. Computer simulation is carried out using the Langevin dynamics method and takes Brownian rotational relaxation of magnetic particles and interparticle interactions into account. The reference theory [Yoshida T.; Enpuku K. Jap. J. Ap. Phys. 2009] is used to estimate computational error. As a result, we give practical recommendations for choosing the optimal input parameters of the numerical algorithm, which make it possible to obtain reliable results of the dynamic susceptibility of a ferrofluid in a high-amplitude AC field in a wide frequency range. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was funded by the Ministry of Science and Higher Education of the Russian Federation (Ural Mathematical Center project No. 075-02-2021-1387)

Obstructive sleep apnea syndrome and cardiovascular risk factors in the antihypertensive therapy “escape” phenomenon

Aim. To assess the role of obstructive sleep apnea and other cardiovascular (CV) risk factors in the development of the antihypertensive therapy (AHT) efficacy escape phenomenon in patients with arterial hypertension (AH). Materials and methods. The data of 75 patients with AH stage III, grades 13 were proceeded. All patients included in the study underwent night respiratory monitoring. After AHT prescription, blood pressure (BP) was monitored by three measurement methods (office, daily monitoring and self-control of blood pressure) initially, in 1, 3 and 6 months after the inclusion in order to confirm the initial therapy efficacy and to identify or exclude the escape phenomenon. Results. In 36.0% of patients, the escape phenomenon was diagnosed in 1 or 3 months of observation. When comparing the group with the escape phenomenon, an initially higher level of systolic BP was revealed according to office measurements, 24-hour monitoring and self-control BP monitoring (134.04.7 mmHg vs 126.08.5 mmHg; 129.02.3 mmHg vs 121.07.7 mmHg; 131.08.2 mmHg vs 121.56.2 mmHg resp.; р0,05). There were no differences in sleep apnea and CV risk factors between the groups. However in patients with a minimal SpO285% during sleep, there were a higher levels of office systolic BP both before the AHT prescription, and during its use (157.610.4 mmHg vs 152.48.1 mmHg resp., р0,05; 132.06.8 vs 127.18.9 mmHg resp.; р0,05), and mean 24-hour systolic BP (125.75.9 vs 121.68.2 mmHg resp.; р0,05) compared with patients with a minimum SpO285%. Conclusion. The higher BP level in patients with lover nocturnal hypoxemia does not allow us to exclude the delayed negative impact of obstructive sleep apnea, especially severe, on the BP profile in case of initially successful AH control

The Dynamic Magnetic Susceptibility of a Ferrofluid: the Influence of Interparticle Interactions and Ac Field Amplitude

Целью данной работы является описание одновременного влияния как диполь-дипольных взаимодействий, так и амплитуды поля на динамическую восприимчивость и релаксационные процессы в феррожидкостях. Для этого будут построены формулы, отражающие зависимость диполь­дипольных и поле-дипольных взаимодействий. Акцент ставится на изучение области высоких амплитуд магнитного поля и восприимчивости Ланжевена. Полученные приближенные формулы для динамической восприимчивости комплексно предсказываю динамический отклик феррожидкостей, одновременно учитывая влияние амплитуды переменного поля и диполь-дипольных взаимодействий.This work describes the influence of dipole-dipole interactions and the field amplitude on the dynamic susceptibility and relaxation processes in ferrofluids. For this purpose, we will construct formulas reflecting the dipole-dipole and field-dipole interactions dependence. The main direction is the study of the region of high amplitudes of the magnetic field and the Langevin susceptibility. Approximate formulas for the dynamic susceptibility complexly predict the dynamic response of ferrofluids. At the same time, the influence of the amplitude of the alternating field and dipole-dipole interactions are considered

STATIC MODELING OF THE INFLUENCE OF RISK FACTORS ON THE HEALTH INDICATORS OF METALLURGICAL PRODUCTION WORKERS

Occupational risk assessment for metallurgical workers' health is relevant. The paper analyzes industrial and individual factors affecting musculoskeletal and endocrine prevalence of the diseases. ANOVA methods were used. The combined interaction of these factors was demonstrated

Changes of metabolic parameters in patients with primary hyperparathyroidism of different age groups

BACKGROUND: Studies have shown a high incidence of metabolic disorders and cardiovascular diseases in patients with primary hyperparathyroidism (PHPT). PHPT is usually diagnosed in people of age over 50 years and therefore age-associated changes of metabolism should be excluded. Researching predictors of cardiovascular pathology contributes to choosing optimal approaches to personalized patient management.AIM: To determine the features of metabolic disorders in patients of various age groups with confirmed active stage of PHPT.MATERIALS AND METHODS: A single-center observational retrospective comparative study of patients with active PHPT at the age of 18-49 years (Group 1, n=66) and over 50 years (Group 2, n=290) was carried out. The exclusion criteria for both groups were: persistent PHPT or recurrence after surgical treatment of the disease in history; clinical/genetically confirmed multiple endocrine neoplasia syndrome; for Group 1 — pregnancy, lactation. The assessment of laboratory parameters of mineral, carbohydrate, fat and purine metabolism obtained during a hospital examination was carried out, the frequencies of various metabolic disorders were determined and compared between age groups.RESULTS: There were no significant differences in parathyroid hormone and serum calcium levels between age groups, however, there were more severe hypercalciuria, a tendency to active bone metabolism and lower vitamin D level in Group 1. Patients of Group 2 had statistically significantly lower glomerular filtration rate and a higher frequency of bone complications. In the same group glycaemia and triglycerides levels were higher (the latter difference has the level of a statistical tendency). These patients also had a higher body mass index and, as a result, a higher incidence of obesity (37% vs 20%, p=0.006) and diabetes mellitus type 2 (12.5% vs 3%, p=0.013). At the same time, patients did not significantly differ in the rates of hypercholesterolemia (62% in Group 1 vs 70% in Group 2, p=0.228), hypertriglyceridemia (27% vs 32%, p=0.433) and hyperuricemia (42% vs 50%, p=0.302), significantly exceeding similar indicators in the general Russian population.CONCLUSION: Carbohydrate disorders are more often observed in patients older than 50 years, providing an increased prevalence of diabetes mellitus type 2 among patients with PHPT compared with the general population. The high incidence of various types of dyslipidemia and hyperuricemia in the primary parathyroid pathology has no age specific features. Thereby these disorders are significant risk factors of cardiovascular diseases, even in young people with PHPT