[Evaluation of the accuracy of modern intraocular lens calculation formulas when optical biometry is not possible]. / Otsenka tochnosti sovremennykh formul rascheta intraokulyarnykh linz pri nevozmozhnosti vypolneniya opticheskoi biometrii.

PURPOSE: This study evaluates the accuracy of modern intraocular lens (IOL) calculation formulas using axial length (AL) data obtained by ultrasound biometry (UBM) compared to the third-generation SRK/T calculator. MATERIAL AND METHODS: The study included 230 patients (267 eyes) with severe lens opacities that prevented optical biometry, who underwent phacoemulsification (PE) with IOL implantation. IOL power calculation according to the SRK/T formula was based on AL and anterior chamber depth obtained by UBM (Tomey Biometer Al-100) and keratometry on the Topcon KR 8800 autorefractometer. To adapt AL for new generation calculators - Barrett Universal II (BUII), Hill RBF ver. 3.0 (RBF), Kane and Ladas Super Formula (LSF) - the retinal thickness (0.20 mm) was added to the axial length determined by UBM, and then the optical power of the artificial lens was calculated. The mean error and its modulus value were used as criteria for the accuracy of IOL calculation. RESULTS: A significant difference (p=0.008) in the mean IOL calculation error was found between the formulas. Pairwise analysis revealed differences between SRK/T (-0.32±0.58 D) and other formulas - BUII (-0.16±0.52 D; p=0.014), RBF (-0.17±0.51 D; p=0.024), Kane (-0.17±0.52 D; p=0.029), but not with the LSF calculator (-0.19±0.53 D; p=0.071). No significant differences between the formulas were found in terms of mean error modulus (p=0.238). New generation calculators showed a more frequent success in hitting target refraction (within ±1.00 D in more than 95% of cases) than the SRK/T formula (86%). CONCLUSION: The proposed method of adding 0.20 mm to the AL determined by UBM allows using this parameter in modern IOL calculation formulas and improving the refractive results of PE, especially in eyes with non-standard anterior segment structure.

Experimental and Theoretical Studies of Green Synthesized Cu2O Nanoparticles Using Datura Metel L.

In biomedical applications, Cu2O nanoparticles are of great interest. The bioengineered route is eco-friendly for the synthesis of nanoparticles. Therefore, in the present study, there is an attempt to synthesis Cu2O nanoparticles using Datura metel L. The synthesized nanoparticles were characterized by UV-Vis, XRD, and FT-IR. UV-Vis results suggest the presence of hyoscyamine, atropine in Datura metel L, and also, nanoparticles formation has been confirmed by the presence of absorption peak at 790 nm. The average crystallite size (19.56 nm) was obtained by XRD. FT-IR was also used to confirm the different functional groups. Fourier Power Spectrum was also employed to examine the synthesized nanomaterials spectrum data to emphasize the peak of the prominent frequencies. Density functional theory (DFT) was also utilized to assess the energy of the substance over time, which appears to indicate a stable molecule. Furthermore, calculated energies, thermodynamic properties (such as enthalpies, entropies, and Gibbs-free energies), modeled structures of complexes, crystals, and clusters, and predicted yields, rates, and regio- and stereospecificity of reactions were all in good agreement with experimental results. Overall, the results show that the successful production of Cu2O nanoparticles with Datura metel L. corresponds to theoretical research.

[Optimization of intraocular lens power calculation in pseudoexfoliation syndrome]. / Optimizatsiya rascheta intraokulyarnykh linz pri psevdoeksfoliativnom sindrome.

PURPOSE: To assess the impact of pseudoexfoliation syndrome (PEX) on the accuracy of intraocular lens (IOL) power calculation. MATERIAL AND METHODS: The study included 243 patients who underwent phacoemulsification (PE); they were divided into the control (no PEX signs, n=131) and study (signs of PEX, n=112) groups. Barrett Universal II formula was used for IOL calculation by optical biometry (IOL-Master 500). Obtained refraction (autorefractometer Topcon-8800) was compared with target refraction to assess IOL calculation accuracy 1 month after PE. RESULTS: Patients with PEX had significantly shallower anterior chamber compared to the control group (2.86±0.43 versus 3.0±0.43 mm, p=0.003) and steeper corneal curvature (44.31±1.5 versus 43.7±2.59 D, p=0.052). There was significant difference in absolute error of IOL calculation between the groups (-0.02±0.45 versus 0.17±0.55 D for control and study groups, respectively, p=0.004). There was no difference in IOL calculation error depending on the implanted IOL models (AcrySof SA60AT and Akreos Adapt AO) in the control group. However, implantation of SA60AT in the study group showed significant difference in IOL calculation error compared with Akreos (0.3±0.57 versus 0.04±0.51 D, p=0.01). Using linear regression, optimized A-constants were suggested for these types of IOLs for patients with PEX (118.83 for SA60AT and 118.44 for Akreos).

[The influence of pseudoexfoliation syndrome on central retina in elderly patients.]

PURPOSE: to evaluate the effect of pseudoexfoliation syndrome (PXF) on the stage of age-related macular degeneration (AMD) and central retinal thickness, measured by optical coherence tomography (OCT) in elderly patients living in Saint-Petersburg. 25 elderly patients (30 eyes) with PXF and 25 age-matched patients (29 eyes) without PXF (control group) were included in the study. Retinal thickness in fovea and parafovea as well as AMD stage were compared in the groups. Thickness of fovea and parafovea was measured with OCT, the stage of AMD was graded according AREDS criteria. The mean fovea and parafovea thickness in PXS group were not significantly different compared with control group (p>0,05). There was no significant difference between two groups in the stage of AMD, graded according AREDS criteria (p>0,05). The effect of PXS on central retinal thickness and the stage of AMD was not found in Saint-Petersburg elderly population.

Results and Prospects of Using Activator of Hematopoietic Stem Cell Differentiation in Complex Therapy for Patients with COVID-19.

The paper presents the results of a standard and complex treatment method using the peptide drug thymus thymalin in patients with COVID-19. One of the mechanisms of the immunomodulatory effect of thymalin is considered to be the ability of this peptide drug to influence the differentiation of human hematopoietic stem cells (HSCs). It was found that, as a result of standard treatment, patients in the control group showed a decrease in the concentration of the pro-inflammatory cytokine IL-6, C-reactive protein, D-dimer. The addition of thymalin to standard therapy accelerated the decline in both these indicators and the indicators of the T cell system. This has helped reduce the risk of blood clots in COVID-19 patients. The revealed properties of the thymus peptide preparation are the rationale for its inclusion in the complex treatment of coronavirus infection. Peptideswith potential biological activity against SARS-CoV-2 virus [29]. Note: Nitrogen atoms are shown in blue, oxygen atoms - in red, carbon atoms - in gray, hydrogen atoms - in white, and phosphorus atoms - in yellow.

[Age and nosological structure of ophthalmological diseases of patients of the ophthalmological center of Saint-Petersburg in 2015-2019.]

About 1,3 billion people live on our planet with visual disorders such as cataract and glaucoma, the prevalence of which is significantly higher in the elderlypopulation. Eye diseases remain a global medical, social and economic problem, associated with both the progression of the disease to blindness and the lack of pathogenetic therapy methods. A retrospective analysis of the long-term dynamics and structure of cases of ophthalmological diseases of patients treated in a large multidisciplinary hospital was carried out. The age and nosological structure of eye diseases is described. Natural features of the structure of diseases relative to different age groups have been revealed, as well as patterns in dynamics have been found.

[Features of the picture of blood cells in elderly persons with primary open-angle glaucoma.]

Around 1,3 billion people live worldwide with visual analyzer disorders such as glaucoma and cataract. These diseases are particularly common among the elderly. From glaucoma every year 10 million people completely lose vision, one of the factors of which is untimely diagnosis. Donosological diagnosis and laboratory screening can play a key role in detecting this pathology and significantly improving the quality of life of the older generation. The article presents the results of comparative analysis of the general blood analysis of glaucoma patients with a control group. The hematological indices are also compared by sex and age. Changes in some indicators consistent with existing theories of glaucoma pathogenesis have been identified. Promising directions of application of general blood analysis as a routine method of additional diagnostics of glaucoma in the future are planned.

[Laboratory predictors of glaucoma in patients with middle and old age - a tool to improve the quality of life (literature review).]

There are about 1,3 billion people worldwide with visual disorders such as cataract and glaucoma, the prevalence of which is significantly higher in elder persons. Eye diseases remain a global medical, social and economic problem, associated with both the progression of the disease up to blindness and the lack of pathogenetic therapy methods. Timely detection of pathology is secondary prevention of glaucoma. At present, a number of diagnostic techniques have been developed, including mainly instrumental techniques. Undoubtedly, laboratory indicators should be used as screening methods of early diagnosis. Today, a group of biomarkers with different degrees of sensitivity and specificity has been identified. However, these markers have some difficulty in indicating. Finding signs of glaucoma in complete blood count is an important task. Glaucoma is recognized as a systemic disease, which should be reflected in the change in morphofunctional properties of blood elements.

Variation in predicted internal concentrations in relation to PBPK model complexity for rainbow trout.

The present study is motivated by the increasing demand to consider internal partitioning into tissues instead of exposure concentrations for the environmental toxicity assessment. To this end, physiologically based pharmacokinetic (PBPK) models can be applied. We evaluated the variation in accuracy of PBPK model outcomes depending on tissue constituents modeled as sorptive phases and chemical distribution tendencies addressed by molecular descriptors. The model performance was examined using data from 150 experiments for 28 chemicals collected from US EPA databases. The simplest PBPK model is based on the "Kow-lipid content" approach as being traditional for environmental toxicology. The most elaborated one considers five biological sorptive phases (polar and non-polar lipids, water, albumin and the remaining proteins) and makes use of LSER (linear solvation energy relationship) parameters to describe the compound partitioning behavior. The "Kow-lipid content"-based PBPK model shows more than one order of magnitude difference in predicted and measured values for 37% of the studied exposure experiments while for the most elaborated model this happens only for 7%. It is shown that further improvements could be achieved by introducing corrections for metabolic biotransformation and compound transmission hindrance through a cellular membrane. The analysis of the interface distribution tendencies shows that polar tissue constituents, namely water, polar lipids and proteins, play an important role in the accumulation behavior of polar compounds with H-bond donating functional groups. For compounds without H-bond donating fragments preferable accumulation phases are storage lipids and water depending on compound polarity.

Mutations in fd phage major coat protein modulate affinity of the displayed peptide.

Multibillion-clone libraries of phages displaying guest peptides fused to the major coat protein pVIII (landscape libraries) are a rich source of probes for proteinaceous and non-proteinaceous targets. As opposed to the pIII-type fusion phages, which display peptides as independent structural domains, the guest peptides in the pVIII-fusion phages can be structurally and functionally influenced by contiguous subunits. To decipher the impact of the locale of a guest peptide on its affinity characteristics, we constructed a library of phages carrying beta-galactosidase-binding peptide ADTFAKSMQ at the N-terminus of the pVIII protein surrounded by random amino acids. It was found that mutagenesis of amino acids 12-19 (domain C) has polar effects on target binding affinity of the displayed peptide. The phages with highest affinity are characterized by: (i) a net electrostatic charge around -1 of domain C of the mutated phages at pH 7.0; (ii) a lower radius of cylinder coaxial to alpha-helix formed by domain C; (iii) a lower higher occupied molecular orbital (HOMO) of domain C leading to a decreased formation of hydrogen bonds and (iv) positively charged surface and torsion energy of domain C, which may require a conformational transition of N-terminal peptide ADTFAKSMQ for its binding with beta-galactosidase. Influence of the guest peptide on the diversity of mutations in the neighboring landscape area was also observed.

[Comparative characteristics of current tonometric methods].

Corneal thickness is known to have a considerable impact on the results of applanation tonometry. A Pascal dynamic contour tonomer (SMT Swiss Microtechnology AG) the readings of which are not affected by the properties of the cornea has recently come into the world market. The objective of the investigation was to comparatively evaluate Pascal, Goldmann, and Maklakov tonometers. The mean intraocular pressure measured by various procedures significantly differed. The greatest correlation was found between dynamic contour tonometry and Goldmann's tonometry. The Pascal and Goldmann tonometers underestimated data on remeasurements. The results of applanation procedures, unlike those of dynamic contour tonometry, depend on the data of keratopachymetry.

[A study of conformational states of substrates of cytochrome P450 3A4].

A multiconformational study of substrates of cytochrome P450 3A4 has been carried out within the BiS/MC algorithm. The method allowed one to create a pseudoatomic model of the cytochrome and to find the substrate conformers responsible for the interaction with the cytochrome. It has been found that, in most cases, the geometry of the acting conformer is much different from the geometry of the global minimum conformer. It has been shown that the mirror conformational antipodes ("enantioconformers") are characterized as a rule by different Michaelis constants. A quantitative relationship between the Michaelis constants and the parameters of interactions in "model 3A4 isoform-substrate" complexes has been determined. The relationship describes the experimental value of Michaelis constant with the squared cross-validation correlation coefficient of 0.88.

[Role of homocysteine in the pathogenesis of vascular complications of type 2 diabetes].

The purpose of the investigation was to study the plasma levels of homocysteine (HC) inpatients with type 2 diabetes mellitus (DM2) and its association with the development of diabetic angiopathies and some clinical and laboratory parameters. Among 92 patients with DM2, hyperhomocysteinemia (22.6±6.1 µmol/l) was detected in 53% (Group 1) whereas the level of HC was normal (11.3±2.7 µmol/l). The signs of macro- and microangiopathy (nephropathy, in particular) were more common In patients with elevated HC levels than in those with normal HC levels (70% versus 21%; p <0.001; 73% versus 26%; p = 0.008). The carbohydrate and lipid metabolic values and the type of sugar-reducing therapy did not affect the level of HC whereas a clear correlation was found between HC and glomerular filtration rate(GFR), albuminuria, age, and systolic blood pressure. Thus, elevated plasma HC levels in patients with DM2 are associated with the high risk of vascular events and with renal functional parameters (GFR, albuminuria).

New type of phase transformation in gas hydrate forming system at high pressures. Some experimental and computational investigations of clathrate hydrates formed in the SF6-H2O system.

In this work, we present a new, previously unknown type of structure transformation in the high-pressure gas hydrates, which is related to the existence of two different isostructural phases of the sulfur hexafluoride clathrate hydrates. Each of these phases has its own stability field on the phase diagram. The difference between these hydrates consists of partial filling of small D cages by SF(6) molecules in the high-pressure phase; at 900 MPa, about half of small cages are occupied. Our calculations indicate that the increase of population of small cavities is improbable, therefore, at any pressure value, a part of the cavities remains vacant and the packing density is relatively low. This fact allowed us to suppose the existence of the upper pressure limit of hydrate formation in this system; the experimental results obtained confirm this assumption.

Molecular and crystal properties of ethyl 4,6-dimethyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate from experimental and theoretical electron densities.

The electron density and electronic energy densities in ethyl 4,6-dimethyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate have been studied from accurate X-ray diffraction measurements at 110 K and theoretical single-molecule and periodic crystal calculations. The Quantum Theory of Atoms in Molecules and Crystals (QTAMC) was applied to analyze the electron-density and electronic energy-density features to estimate their reproducibility in molecules and crystals. It was found that the local electron-density values at the bond critical points derived by different methods are in reasonable agreement, while the Laplacian of the electron density computed from wavefunctions, and electron densities derived from experimental or theoretical structure factors in terms of the Hansen-Coppens multipole model differ significantly. This disagreement results from insufficient flexibility of the multipole model to describe the longitudinal electron-density curvature in the case of shared atomic interactions. This deficiency runs through all the existing QTAMC bonding descriptors which contain the Laplacian term. The integrated atomic characteristics, however, suffer noticeably less from the aforementioned shortcoming. We conclude that the electron-density and electronic energy QTAMC characteristics derived from wavefunctions, especially the integrated quantities, are nowadays the most suitable candidates for analysis of the transferability of atoms and atomic groups in similar compounds.

[The incidence and primary multiplicity of colon cancer].

Analysis of Moscow cancer register demonstrates a steady growth of colon cancer (CC) incidence and mortality in Moscow, also noted in all large industrial cities of economically developed countries. In Moscow between 1996 and 2001, the incidence of CC had grown 1.5 times (from 19.6 up to 30% per 100,000), and the CC-related mortality had grown twice (from 9.1 up to 19.5% per 100,000). The incidence of CC among women is 1.5 to 2 times higher than that among men. The burst of CC incidence is noted after age 55, and the peak incidence is noted at age 65. Not rare (2.9% of cases) are tumors that develop simultaneously in different divisions of the colon, which are diagnosed during the surgery or are omitted even then. Such synchronous large bowel tumors are found mostly in patients over 60. The analysis show that metachronous tumors (3.4% of cases) usually develop in the colon 8 to 10 years after the first surgery for CC, or some other cancer, and are found mostly in patients over 70. Unlike foreign statistics on multicentric CC cancer, according to which primary-multiple (synchronous and metachronous) cancers occur in 1.24 to 14% of cases, Moscow statistics demonstrate a lower likelihood of such a pathology in Muscovites. To sum up, patients who underwent treatment for CC or any other cancer should keep being under an oncologist's observation due to the likelihood of the development of a metachronous colon tumor 8 to 10 years later.

[The modeling of interactions of the CYP2E1 isoform of human cytochrome P450 with substrates].

The interactions between the substrates of the 2E1 isoform of the human cytochrome P450 and receptor were simulated. It was found that the CP4 isoform of the cytochrome of the bacterial cell is highly homologous to the 2E1 isoform of the human cytochrome P450. The orientation of the substrates of the 2E1 isoform in the CP4 isoform of the bacterial cell cytochrome was performed. A cavity in the receptor was found that is responsible for the binding of the substrate. Amino acid residues Phe87, Pro89, Val119, Thr185, Leu244, Leu245, Leu246, Val247, Gly248, Gly249, Thr252, Val295, Asp297, Cys357, Ile395, and Val396, the heme, and water molecules are involved in the formation of the cavity. The mode of the interactions of the substrate molecule with cytochrome was analyzed. Active sites of the receptor, and a part of the substrate molecule responsible for the binding to cytochrome were found. Equations for the dependence of the Michaelis constant on the structural parameters of complexes of substrates with cytochrome were derived.

[Ultrastructure of the Mauthner neurons in goldfish fry after their adaptation to vestibular stimulation]. / Ul'trastruktura Mautnerovskikh neironov mal'kov zolotoi rybki posle adaptatsii k vestibuliarnoi stimuliatsii.

The ultrastructure of the Mauthner cells (M-cells) of goldfish fries was investigated under four different functional states: a) intact (native fishes), b) fatigue (intact fishes subjected to a prolonged vestibular stimulation), c) adapted (intact fishes after a prolonged training session of the daily short vestibular stimuli), d) excited (adapted fishes subjected to a prolonged vestibular stimulation). It has been first found that the fatigue of the M-cells may result in destructive changes of their cytoskeleton. Besides, in the afferent synapses of both adapted and excited M-cells numerous dense-cored vesicles were revealed near the active zones. The data show the neuronal cytoskeleton to be the central target susceptible to damage upon stimulation. The training leads presumably to stabilization of the cytoskeleton ultrastructure. The dense-cored vesicles were suggested to play an active role in the process.

[Changes in the immune system indices of diabetes mellitus patients]. / Izmenenie nekotorykh pokazatelei immunnoi sistemy u bol'uykh sakharnym diabetom.

A decrease in the amount of T-lymphocytes and the total amount of lymphocytes in the peripheral blood occurs in diabetes mellitus patients with hyperglycemia over 150 mg%; a decrease in the amount of T-active lymphocytes occurs but in 350 mg% and upwards. A decrease in the amount of B-lymphocytes is noted in hyperglycemia over 200 mg%. The reaction of blast-cell transformation is sharply suppressed in a grave form of diabetes mellitus whereas in moderately grave conditions its decrease is less noticeable. It is assumed that disorder of cellular immunity can be one of the factors contributing to the development of pyoseptic diseases in diabetes mellitus patients.