Cryostructuring of Polymeric Systems: 67 Properties and Microstructure of Poly(Vinyl Alcohol) Cryogels Formed in the Presence of Phenol or Bis-Phenols Introduced into the Aqueous Polymeric Solutions Prior to Their Freeze-Thaw Processing.

Poly(vinyl alcohol) (PVA) physical cryogels that contained the additives of o-, m-, and p-bis-phenols or phenol were prepared, and their physico-chemical characteristics and macroporous morphology and the solute release dynamics were evaluated. These phenolic additives caused changes in the viscosity of initial PVA solutions before their freeze-thaw processing and facilitated the growth in the rigidity of the resultant cryogels, while their heat endurance decreased. The magnitude of the effects depended on the interposition of phenolic hydroxyls in the molecules of the used additives and was stipulated by their H-bonding with PVA OH-groups. Subsequent rinsing of such "primary" cryogels with pure water led to the lowering of their rigidity. The average size of macropores inside these heterophase gels also depended on the additive type. It was found also that the release of phenolic substances from the additive-containing cryogels occurred via virtually a free diffusion mechanism; therefore, drug delivery systems such as PVA cryogels loaded with either pyrocatechol, resorcinol, hydroquinone, or phenol, upon the in vitro agar diffusion tests, exhibited antibacterial activity typical of these phenols. The promising biomedical potential of the studied nanocomposite gel materials is supposed.

Efficacy of Micronized Purified Flavonoid Fraction in the Posthemorrhoidectomy Period Trial: Open-Label Randomized Controlled Trial.

BACKGROUND: Frequent early postoperative complications of hemorrhoidectomy are thrombosis and edema of mucocutaneous "bridges." OBJECTIVE: This study aimed to investigate the efficacy of micronized purified flavonoid fraction in preventing complications after elective hemorrhoidectomy. DESIGN: Prospective unicentral open-label randomized controlled trial. SETTINGS: 2021-2022 at the Clinic of Colorectal and Minimally Invasive Surgery at Sechenov University (Moscow, Russia). PATIENTS: Patients who underwent hemorrhoidectomy for grade III and IV hemorrhoids. INTERVENTIONS: After hemorrhoidectomy, patients were randomly assigned either to standard treatment (peroral nonsteroid anti-inflammatory drugs and local anesthetics, topical steroids, psyllium, warm sitz baths, and nifedipine gel), referred to as the control group, or to standard treatment with micronized purified flavonoid fraction, referred to as the study group, and followed up for 60 days. MAIN OUTCOME MEASURES: Thrombosis or edema of mucocutaneous bridges and pain intensity on a visual analog scale оn postoperative days 1-7, 14, 21, and 30; quality of life and patient-assessed treatment effect оn postoperative days 1, 3, 7, 21, and 30; and perianal skin tags оn postoperative day 60. RESULTS: The data from 50 patients were analyzed (25 in each group). The visual analog scale demonstrated no differences between groups in each follow-up point. Compared to the control group, the patients in the study group had a significantly higher patient-assessed treatment effect оn postoperative days 1, 3, 7, 21, and 30 and a significantly lower rate of thrombosis or edema of mucocutaneous bridges оn postoperative days 1-7 and 14. Patients in the study group had significantly lower rates of perianal skin tags. LIMITATIONS: Unicenter open-label design. CONCLUSIONS: Micronized purified flavonoid fraction in the posthemorrhoidectomy period is an effective adjunct to standard treatment that helps reduce the rate of thrombosis and edema of mucocutaneous bridges, improves patient-assessed treatment effect, and prevents postoperative perianal skin tags formation. Micronized purified flavonoid fraction in the posthemorrhoidectomy period is not associated with additional pain relief in comparison with nonmicronized purified flavonoid fraction standard treatment. See Video Abstract . EFICACIA DE LA FRACCIN DE FLAVONOIDES PURIFICADA MICRONIZADA EN EL PERODO POSTERIOR A LA HEMORROIDECTOMA ENSAYO MOST ENSAYO CONTROLADO, ALEATORIZADO, ABIERTO: ANTECEDENTES:Una complicación postoperatoria temprana frecuente de la hemorroidectomía es la trombosis y el edema de los "puentes" mucocutáneos.OBJETIVO:Investigamos la eficacia de la fracción de flavonoides purificada micronizada en la prevención de complicaciones después de una hemorroidectomía electiva.DISEÑO:Ensayo controlado aleatorio, prospectivo, unicentral, abierto.AJUSTES:2021-2022 Clínica de Cirugía Colorrectal y Mínimamente Invasiva Universidad Sechenov (Moscú, Rusia).PACIENTES:Pacientes después de hemorroidectomía, que se realizó para hemorroides de grado III-IV.INTERVENCIONES:Después de la hemorroidectomía, los pacientes fueron asignados aleatoriamente al tratamiento estándar (antiinflamatorios no esteroides perorales y anestésicos locales, esteroides tópicos, psyllium, baños de asiento tibios, gel de nifedipina) - grupo de control, o al tratamiento estándar con flavonoide purificado micronizado. fracción (grupo de estudio) y seguido durante 60 días.RESULTADOS DE MEDIDAS PRINCIPALES:Trombosis o edema de puentes mucocutáneos e intensidad del dolor en una escala analógica visual entre el 1.º, 7.º, 14.º, 21.º y 30.º día postoperatorio; calidad de vida y efecto del tratamiento evaluado por el paciente el día 1, 3, 7, 21 y 30 del postoperatorio; Marcas cutáneas perianales en el día 60 del postoperatorio.RESULTADOS:Se analizaron los datos de 50 pacientes (25 en cada grupo). La escala analógica visual no demostró diferencias entre grupos en cada punto de seguimiento. En comparación con el grupo de control, los pacientes en el grupo de estudio tuvieron un efecto del tratamiento evaluado por el paciente significativamente mayor en los días 1, 3, 7, 21 y 30 después de la operación, una tasa significativamente menor de trombosis o edema de los puentes mucocutáneos en los días 1, 7 y 14.. Los pacientes del grupo de estudio tuvieron tasas significativamente más bajas de marcas en la piel perianal.LIMITACIONES:Diseño Unicenter de etiqueta abierta.CONCLUSIONES:La fracción de flavonoides purificada micronizada en el período posterior a la hemorroidectomía es un complemento eficaz del tratamiento estándar que ayuda a reducir la tasa de trombosis y edema de los puentes mucocutáneos, mejora el efecto del tratamiento evaluado por el paciente y previene la formación de marcas cutáneas perianales posoperatorias. La fracción de flavonoides purificados micronizados en el período posterior a la hemorroidectomía no se asocia con un alivio adicional del dolor en comparación con el tratamiento estándar con la fracción de flavonoides purificados no micronizados. (Traducción-Yesenia Rojas-Khalil ).

An Artificial Intelligence-Based Support Tool for Lumbar Spinal Stenosis Diagnosis from Self-Reported History Questionnaire.

OBJECTIVES: Symptomatic lumbar spinal stenosis (LSS) leads to functional impairment and pain. While radiologic characterization of the morphological stenosis grade can aid in the diagnosis, it may not always correlate with patient symptoms. Artificial intelligence (AI) may diagnose symptomatic LSS in patients solely based on self-reported history questionnaires. METHODS: We evaluated multiple machine learning (ML) models to determine the likelihood of LSS using a self-reported questionnaire in patients experiencing low back pain and/or numbness in the legs. The questionnaire was built from peer-reviewed literature and a multidisciplinary panel of experts. Random forest, lasso logistic regression, support vector machine, gradient boosting trees, deep neural networks, and automated machine learning models were trained and performance metrics were compared. RESULTS: Data from 4827 patients (4690 patients without LSS: mean age 62.44, range 27-84 years, 62.8% females, and 137 patients with LSS: mean age 50.59, range 30-71 years, 59.9% females) were retrospectively collected. Among the evaluated models, the random forest model demonstrated the highest predictive accuracy with an area under the receiver operating characteristic curve (AUROC) between model prediction and LSS diagnosis of 0.96, a sensitivity of 0.94, a specificity of 0.88, a balanced accuracy of 0.91, and a Cohen's kappa of 0.85. CONCLUSIONS: Our results indicate that ML can automate the diagnosis of LSS based on self-reported questionnaires with high accuracy. Implementation of standardized and intelligence-automated workflow may serve as a supportive diagnostic tool to streamline patient management and potentially lower health care costs.

Thrombosed external hemorrhoids during pregnancy: surgery versus conservative treatment.

The management of thrombosed external hemorrhoids (TEH) during pregnancy is still under debate because of the fear of potential adverse effects on the fetus. This study aims to compare efficacy and safety of conservative versus surgical treatment of acute TEH in pregnant women. Furthermore, the outcome of two different surgical approaches was evaluated. This is a prospective observational study including a sub-analysis on two randomized groups of pregnant women affected by TEH. The primary outcome measured was the impact of conservative and surgical treatment defined in terms of VAS, clinical patient grading assessment scale (CPGAS) and the SF-12 questionnaire. In a randomized sub-analysis of the surgical treatment, the outcome of local excision (LE) versus thrombectomy (TE) was compared. Fifty-three patients entered the study. Twenty-six patients had conservative treatment and 22 underwent surgery. Within the surgical group, 8 were randomized for TE and 14 for LE. VAS, SF-12 and CPGAS improved in both groups after 3 and 10 days from the treatment. However, physical (PCS) and mental health (MCS) domains of the SF-12 and CPGAS showed a significant difference in favor of surgery on the 10th day (PCS: p < 0.002 and MCS: p = 0.03; CPGAS: p = 0.002). The surgical group showed an earlier significant reduction of pain on the 3rd day (p = 0.0004). In the surgical group, randomization was halted due to ethical concerns arising from a notable difference in the primary end point between subgroups during interim analysis. Specifically, the re-thrombosis rate was 38% (3/8) after TE and 7% (1/14) after LE. No complications occurred for either mothers or fetuses. Both surgical and conservative treatments are safe and effective. However, surgery allows a faster relief of anal pain. Thrombectomy is associated with higher risk of re-thrombosis when compared to local excision (clinicaltrials.gov ID number NCT04588467).

Constrained DFT-based magnetic machine-learning potentials for magnetic alloys: a case study of Fe-Al.

We propose a machine-learning interatomic potential for multi-component magnetic materials. In this potential we consider magnetic moments as degrees of freedom (features) along with atomic positions, atomic types, and lattice vectors. We create a training set with constrained DFT (cDFT) that allows us to calculate energies of configurations with non-equilibrium (excited) magnetic moments and, thus, it is possible to construct the training set in a wide configuration space with great variety of non-equilibrium atomic positions, magnetic moments, and lattice vectors. Such a training set makes possible to fit reliable potentials that will allow us to predict properties of configurations in the excited states (including the ones with non-equilibrium magnetic moments). We verify the trained potentials on the system of bcc Fe-Al with different concentrations of Al and Fe and different ways Al and Fe atoms occupy the supercell sites. Here, we show that the formation energies, the equilibrium lattice parameters, and the total magnetic moments of the unit cell for different Fe-Al structures calculated with machine-learning potentials are in good correspondence with the ones obtained with DFT. We also demonstrate that the theoretical calculations conducted in this study qualitatively reproduce the experimentally-observed anomalous volume-composition dependence in the Fe-Al system.

Synthesis under Normal Conditions and Morphology and Composition of AlF3 Nanowires.

AlF3 has interesting electrophysical properties, due to which the material is promising for applications in supercapacitors, UV coatings with low refractive index, excimer laser mirrors, and photolithography. The formation of AlF3-based nano- and micro-wires can bring new functionalities to AlF3 material. AlF3 nanowires are used, for example, in functionally modified microprobes for a scanning probe microscope. In this work, we investigate the AlF3 samples obtained by the reaction of initial aluminum with an aqueous hydrofluoric acid solution of different concentrations. The peculiarity of our work is that the presented method for the synthesis of AlF3 and one-dimensional structures based on AlF3 is simple to perform and does not require any additional precursors or costs related to the additional source materials. All the samples were obtained under normal conditions. The morphology of the nanowire samples is studied using scanning electron microscopy. We performed an intermediate atomic force microscope analysis of dissolved Al samples to analyze the reactions occurring on the metal surface. The surface of the obtained samples was analyzed using a scanning electron microscope. During the analysis, it was found that under the given conditions, whiskers were synthesized. The scale of one-dimensional structures varies depending on the given parameters in the system. Quantitative energy-dispersive x-ray spectroscopy spectra are obtained and analyzed with respect to the feedstock and each other.

MLIP-3: Active learning on atomic environments with moment tensor potentials.

Nowadays, academic research relies not only on sharing with the academic community the scientific results obtained by research groups while studying certain phenomena but also on sharing computer codes developed within the community. In the field of atomistic modeling, these were software packages for classical atomistic modeling, and later for quantum-mechanical modeling; currently, with the fast growth of the field of machine-learning potentials, the packages implement such potentials. In this paper, we present the MLIP-3 package for constructing moment tensor potentials and performing their active training. This package builds on the MLIP-2 package [Novikov et al., "The MLIP package: moment tensor potentials with MPI and active learning," Mach. Learn.: Sci. Technol., 2(2), 025002 (2020)], however, with a number of improvements, including active learning on atomic neighborhoods of a possibly large atomistic simulation.

Oxidative damage to ßL-crystallin in vitro by iron compounds formed in physiological buffers.

ßL-crystallin aggregation due to oxidative damage in the presence of H2O2 and ferric chloride was studied in-vitro under conditions close to physiological. It was shown that the protein aggregation characterized by the nucleation time and the aggregation rate significantly depended on the composition of the isoosmotic buffers used, and decreased in the series HEPES buffer > Tris buffer > PBS. Ferric chloride at neutral pH was converted into water-insoluble iron hydroxide III (≡FeIIIOH). According to the data of scanning electron microscopy the ≡FeIIIOH particles formed in HEPES buffer, Tris buffer, and PBS practically did not differ in structure. However, the sizes of ≡FeIIIOH floating particles measured by dynamic light scattering differed significantly and were 44 ± 28 nm, 93 ± 66 nm, 433 ± 316 nm (Zaver ± SD) for HEPES buffer, Tris buffer, and PBS, respectively. It was found by the spin trap method that the ability of ≡FeIIIOH to decompose H2O2 with the formation of a •OH decreases in the series HEPES buffer, Tris buffer, and PBS. The authors suggest that the ability to generate •OH during the decomposition of H2O2 is determined by the total surface area of ≡FeIIIOH particles, which significantly depends on the composition of the buffer in which these particles are formed.

Cryostructuring of Polymeric Systems: 63. Synthesis of Two Chemically Tanned Gelatin-Based Cryostructurates and Evaluation of Their Potential as Scaffolds for Culturing of Mammalian Cells.

Various gelatin-containing gel materials are used as scaffolds for animal and human cell culturing within the fields of cell technologies and tissue engineering. Cryostructuring is a promising technique for the preparation of efficient macroporous scaffolds in biomedical applications. In the current study, two new gelatin-based cryostructurates were synthesized, their physicochemical properties and microstructure were evaluated, and their ability to serve as biocompatible scaffolds for mammalian cells culturing was tested. The preparation procedure included the dissolution of Type A gelatin in water, the addition of urea to inhibit self-gelation, the freezing of such a solution, ice sublimation in vacuo, and urea extraction with ethanol from the freeze-dried matter followed by its cross-linking in an ethanol medium with either carbodiimide or glyoxal. It was shown that in the former case, a denser cross-linked polymer phase was formed, while in the latter case, the macropores in the resultant biopolymer material were wider. The subsequent biotesting of these scaffolds demonstrated their biocompatibility for human mesenchymal stromal cells and HepG2 cells during subcutaneous implantation in rats. Albumin secretion and urea synthesis by HepG2 cells confirmed the possibility of using gelatin cryostructurates for liver tissue engineering.

A defined road to tracheal reconstruction: laser structuring and cell support for rapid clinic translation.

One of the severe complications occurring because of the patient's intubation is tracheal stenosis. Its incidence has significantly risen because of the COVID-19 pandemic and tends only to increase. Here, we propose an alternative to the donor trachea and synthetic prostheses-the tracheal equivalent. To form it, we applied the donor trachea samples, which were decellularized, cross-linked, and treated with laser to make wells on their surface, and inoculated them with human gingiva-derived mesenchymal stromal cells. The fabricated construct was assessed in vivo using nude (immunodeficient), immunosuppressed, and normal mice and rabbits. In comparison with the matrix ones, the tracheal equivalent samples demonstrated the thinning of the capsule, the significant vessel ingrowth into surrounding tissues, and the increase in the submucosa resorption. The developed construct was shown to be highly biocompatible and efficient in trachea restoration. These results can facilitate its clinical translation and be a base to design clinical trials.

A Collagen Basketweave from the Giant Squid Mantle as a Robust Scaffold for Tissue Engineering.

The growing applications of tissue engineering technologies warrant the search and development of biocompatible materials with an appropriate strength and elastic moduli. Here, we have extensively studied a collagenous membrane (GSCM) separated from the mantle of the Giant squid Dosidicus Gigas in order to test its potential applicability in regenerative medicine. To establish the composition and structure of the studied material, we analyzed the GSCM by a variety of techniques, including amino acid analysis, SDS-PAGE, and FTIR. It has been shown that collagen is a main component of the GSCM. The morphology study by different microscopic techniques from nano- to microscale revealed a peculiar packing of collagen fibers forming laminae oriented at 60-90 degrees in respect to each other, which, in turn, formed layers with the thickness of several microns (a basketweave motif). The macro- and micromechanical studies showed high values of the Young's modulus and tensile strength. No significant cytotoxicity of the studied material was found by the cytotoxicity assay. Thus, the GSCM consists of a reinforced collagen network, has high mechanical characteristics, and is non-toxic, which makes it a good candidate for the creation of a scaffold material for tissue engineering.

Life-On-Hold: Lanthanoids Rapidly Induce a Reversible Ametabolic State in Mammalian Cells.

Until now, the ability to reversibly halt cellular processes has been limited to cryopreservation and several forms of anabiosis observed in living organisms. In this paper we show that incubation of living cells with a solution containing ~50 mM neodymium induces a rapid shutdown of intracellular organelle movement and all other evidence of active metabolism. We have named this state REEbernation (derived from the terms REE (rare earth elements) and hibernation) and found that the process involves a rapid replacement of calcium with neodymium in membranes and organelles of a cell, allowing it to maintain its shape and membrane integrity under extreme conditions, such as low pressure. Furthermore, phosphate exchange is blocked as a result of non-dissolvable neodymium salts formation, which "discharged" the cell. We further showed that REEbernation is characterized by an immediate cessation of transcriptional activity in observed cells, providing an intriguing opportunity to study a snapshot of gene expression at a given time point. Finally, we found that the REEbernation state is reversible, and we could restore the metabolism and proliferation capacity of the cells. The REEbernation, in addition to being an attractive model to further investigate the basic mechanisms of cell metabolism control, also provides a new method to reversibly place a cell into "on-hold" mode, opening opportunities to develop protocols for biological samples fixation with a minimum effect on the omics profile for biomedical needs.

Mechanical properties of anterior lens capsule assessed with AFM and nanoindenter in relation to human aging, pseudoexfoliation syndrome, and trypan blue staining.

The purpose of this study is the mechanical characterization of the mid-to- old-age human anterior lens capsules (ALCs) obtained by capsulorhexis using Atomic Force Microscopy (AFM) and a nanoindenter at different spatial scales. The dependencies on the human age, presence or absence of pseudoexfoliation syndrome (PEX), and application of trypan blue staining during the surgery were analyzed. The measurements on both the anterior (AS) and epithelial (ES) sides of the ALC were conducted and the effect of cells present on the epithelial side was carefully accounted for. The ES of the ALC had a homogenous distribution of the Young's modulus over the surface as shown by the macroscale mapping with the nanoindenter and local AFM indentations, while the AS was more heterogeneous. Age-related changes were assessed in groups ranging from the mid-age (from 48 years) to old-age (up to 93 years). We found that the ES was always stiffer than the AS, and this difference decreased with age due to a gradual decrease in the Young's modulus of the ES and an increase in the modulus of the AS. No significant changes were found in the mechanical properties of ALCs of PEX patients versus the PEX-free group, as well as in the properties of the ALC with and without trypan blue staining.

Evaluation of Supercritical CO2-Assisted Protocols in a Model of Ovine Aortic Root Decellularization.

One of the leading trends in the modern tissue engineering is the development of new effective methods of decellularization aimed at the removal of cellular components from a donor tissue, reducing its immunogenicity and the risk of rejection. Supercritical CO2 (scCO2)-assisted processing has been proposed to improve the outcome of decellularization, reduce contamination and time costs. The resulting products can serve as personalized tools for tissue-engineering therapy of various somatic pathologies. However, the decellularization of heterogeneous 3D structures, such as the aortic root, requires optimization of the parameters, including preconditioning medium composition, the type of co-solvent, values of pressure and temperature inside the scCO2 reactor, etc. In our work, using an ovine aortic root model, we performed a comparative analysis of the effectiveness of decellularization approaches based on various combinations of these parameters. The protocols were based on the combinations of treatments in alkaline, ethanol or detergent solutions with scCO2-assisted processing at different modes. Histological analysis demonstrated favorable effects of the preconditioning in a detergent solution. Following processing in scCO2 medium provided a high decellularization degree, reduced cytotoxicity, and increased ultimate tensile strength and Young's modulus of the aortic valve leaflets, while the integrity of the extracellular matrix was preserved.

Porcine heart valve, aorta and trachea cryopreservation and thawing using polydimethylsiloxane.

The most common cryopreservation protocols of biological tissues suitable for their further implantation has some disadvantages and limited to one sample per procedure with no possible repeated freezing in case of clinical needs. This study is aimed to improve a biological tissues cryopreservation by adding a new heat transfer fluid - polydimethylsiloxane (PDMS). To evaluate its efficiency the porcine biological tissues (heart valves, aortic and trachea fragments) were cryopreserved and thawed in low-viscous PDMS. According to the computer simulation, the midsection cooling rate was up to 490 °C/min and the midsection thawing rate was up to 1140 °C/min with admissible temperature uniformity. Cryoprotectants and liquid nitrogen were not used. The quality of tissue cryopreservation was evaluated using a number of histological and immunohistochemical methods (Orcein, H&E, Anti-CD34, Anti-Vimentin, Anti-Actin staining). Cryopreserved tissues showed no significant morphological difference in comparison with control group both in case of immediate thawing, and after 2 months of low temperature storage. Computer simulation of heat transfer showed the thermal limitations of used approach for larger specimens. The use of PDMS is proposed for preservation of vascular tissue in order to implant it in the form of homotransplants or biobanking with the possible additional use of an internal hydrophilic coating to prevent hydrophobization.

Ring polymer molecular dynamics and active learning of moment tensor potential for gas-phase barrierless reactions: Application to S + H2.

Ring polymer molecular dynamics (RPMD) has proven to be an accurate approach for calculating thermal rate coefficients of various chemical reactions. For wider application of this methodology, efficient ways to generate the underlying full-dimensional potential energy surfaces (PESs) and the corresponding energy gradients are required. Recently, we have proposed a fully automated procedure based on combining the original RPMDrate code with active learning for PES on-the-fly using moment tensor potential and successfully applied it to two representative thermally activated chemical reactions [I. S. Novikov et al., Phys. Chem. Chem. Phys. 20, 29503-29512 (2018)]. In this work, using a prototype insertion chemical reaction S + H2, we show that this procedure works equally well for another class of chemical reactions. We find that the corresponding PES can be generated by fitting to less than 1500 automatically generated structures, while the RPMD rate coefficients show deviation from the reference values within the typical convergence error of the RPMDrate. We note that more structures are accumulated during the real-time propagation of the dynamic factor (the recrossing factor) as opposed to the previous study. We also observe that a relatively flat free energy profile along the reaction coordinate before entering the complex-formation well can cause issues with locating the maximum of the free energy surface for less converged PESs. However, the final RPMD rate coefficient is independent of the position of the dividing surface that makes it invulnerable to this problem, keeping the total number of necessary structures within a few thousand. Our work concludes that, in the future, the proposed methodology can be applied to realistic complex chemical reactions with various energy profiles.

A rapid method of whole cell sample preparation for scanning electron microscopy using neodymium chloride.

The quality of electron microscopy (EM) visualization of biological objects is constantly improving, primarily with the usage of more complex technologies, such as serial block-face scanning electron microscopy (SEM), focused ion beam scanning electron microscopy, and array tomography. Here we suggest a new rapid method of whole cell sample preparation for scanning EM using neodymium chloride treatment followed by staining with lead acetate. This variant of sample preparation does not require separate fixation, complete dehydration, and metal sputtering. By means of SEM in the back-scattered electron mode, in the neodymium-treated preparations, we visualized various morphological structures in human cells (nuclei with nucleoli, cytoskeleton, mitochondria) and microbial cells (Staphylococcus epidermidis, Streptococcus pneumoniae, Escherichia coli, and Candida albicans) preserving their species-specific shape and size. Thus, the suggested method provides additional information combining capabilities of SEM in visualizing cellular surface and transmission EM in detecting intracellular structures. Moreover, biological sample preparation with neodymium and lead is fast, informative, and cost-saving indicating a potential for its practical use for environmental SEM, and can be effectively combined with optical microscopy.

Adaptive Changes in the Vestibular System of Land Snail to a 30-Day Spaceflight and Readaptation on Return to Earth.

The vestibular system receives a permanent influence from gravity and reflexively controls equilibrium. If we assume gravity has remained constant during the species' evolution, will its sensory system adapt to abrupt loss of that force? We address this question in the land snail Helix lucorum exposed to 30 days of near weightlessness aboard the Bion-M1 satellite, and studied geotactic behavior of postflight snails, differential gene expressions in statocyst transcriptome, and electrophysiological responses of mechanoreceptors to applied tilts. Each approach revealed plastic changes in the snail's vestibular system assumed in response to spaceflight. Absence of light during the mission also affected statocyst physiology, as revealed by comparison to dark-conditioned control groups. Readaptation to normal tilt responses occurred at ~20 h following return to Earth. Despite the permanence of gravity, the snail responded in a compensatory manner to its loss and readapted once gravity was restored.

Determination of corneal elasticity coefficient using the ORA database.

PURPOSE: To propose a new approach for the study of corneal biomechanics using the Reichert Ocular Response Analyzer (ORA) database, which is based on changes in velocity retardation in the central cornea at the peak of flattening. METHODS: The ORA applanation curve was analyzed using a mathematical technique, which allowed calculation of the elasticity coefficient (Ke), which is primarily characteristic of the elastic properties of the cornea. Elasticity coefficient values were obtained in patients with presumably different biomechanical properties of the cornea: "normal" cornea (71 eyes, normal group), keratoconus (34 eyes, keratoconus group), LASIK (36 eyes, LASIK group), and glaucoma with elevated and compensated intraocular pressure (lOP) (38 eyes, glaucoma group). RESULTS: The mean Ke value in the normal group was 11.05 +/- 1.6, and the corneal thickness correlation coefficient r2 was 0.48. In the keratoconus group, the mean Ke value was 4.91 +/- 1.87 and the corneal thickness correlation coefficient r2 was 0.47. In the LASIK group, Ke and r2 were 5.99 +/- 1.18 and 0.39, respectively. In the glaucoma group, the same eyes that experienced a two-fold reduction in lOP developed a statistically significant reduction in the Ke (1.06 times lower), whereas their corneal hysteresis value increased 1.25 times. CONCLUSIONS: The elasticity coefficient calculated using the ORA applanation curve can be used in the evaluation of corneal biomechanical properties.