Replacement Method Research Articles

Crystal Structure Determination of Nucleotide-sugar Binding Domain of Human UDP-glucuronosyltransferases 2B10.

UDP-glucuronosyltransferases (UGTs) play a crucial role in maintaining endobiotic homeostasis and metabolizing xenobiotic compounds, particularly clinical drugs. However, the detailed catalytic mechanism of UGTs has not been fully elucidated due to the limited availability of reliable protein structures. Determining the catalytic domain of human UGTs has proven to be a significant challenge, primarily due to the difficulty in purifying and crystallizing the full-length protein. This study focused on the human UGT2B10 C-terminal cofactor binding domain, aiming to provide structural insights into the fundamental catalytic mechanisms. In this study, the C-terminal sugar-donor binding domain of human UGT2B10 was purified and crystallized using the vapor-diffusion method. The resulting UGT2B10 CTD crystals displayed high-quality diffraction patterns, allowing for data collection at an impressive resolution of 1.53 Å using synchrotron radiation. Subsequently, the structure of the UGT2B10 CTD was determined using the molecule replacement method with a homologous structure. The crystals were monoclinic, belonging to the space C2 with unit-cell parameters a = 85.90 Å, b = 58.39 Å, c = 68.87 Å, α = γ = 90°, and β = 98.138°. The Matthews coefficient VM was determined to be 2.24 Å3 Da-1 (solvent content 46.43%) with two molecules in the asymmetric unit. The crystal structure of UGT2B10 CTD was solved at a high resolution of 1.53 Å, revealing a conserved cofactor binding pocket. This is the first study determining the C-terminal cofactor binding domain of human UGT2B10, which plays a key role in additive drug metabolism.

X-ray structure of recombinant house dust mite allergen Der p 3

The X-ray structure of the Der p 3 allergen was solved at 2.25 Å resolution using the molecular replacement method. The most remarkable difference in conformation of the polypeptide chains between the Der p 3 allergen and bovine trypsin is observed in the disordered parts of the polypeptide chain where the degree of homology is lower. The active site of the Der p 3 allergen which involves the residues of catalytic triad Ser197, His 52, and Asp97 (Ser195, His57, and Asp102 in bovine trypsin) responsible for the specific binding of the positively charged substrates Asp191 (Asp189 in bovine trypsin) is in the cleft between the domains.

Preliminary X-ray Diffraction Analysis of Purine Nucleoside Phosphorylase from the Haloalkaliphilic Bacterium Halomonas chromatireducens

Crystals of the enzyme purine nucleoside phosphorylase from the extremophilic bacterium Halomonas Chromatireducens AGD 8-3, suitable for X-ray diffraction, were grown by the vapor-diffusion method. The X-ray diffraction data were collected from these crystals at the Belok beamline of the Kurchatov synchrotron radiation source (National Research Centre “Kurchatov Institute”) at 100 K to 1.80 Å resolution. The X-ray diffraction data were processed in the space groups P1, P2, P21, and P622. The structure was solved by the molecular replacement method taking into account the twinning in the space groups P21 and P1 with one and two hexamers of the enzyme per asymmetric unit, respectively.

Synthesis of scale-like nano-hydroxyapatite and preparation of biodegradable woven scaffolds for bone tissue engineering

Bone tissue engineering scaffolds should have bone compatibility, biological activity, porosity, and degradability. In this study, flake-like hydroxyapatite was synthesized by hydrothermal method and mixed with sodium alginate to make a gel, which was injected into a hollow braid. Porous and degradable SA/n-Hap woven scaffolds were prepared by freeze-drying technology. The morphology of hydroxyapatite was characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction. The scaffolds were characterized by an improved liquid replacement method, compression test, and degradation test. The results showed that the hydroxyapatite synthesized at 160 °C had a scaly morphology. The prepared scaffold had a pore size of 5–100 μm, a porosity of 60%−70%, and a swelling rate of more than 300%. After 21 d the degradation rate reached 5.54%, and a cell survival rate of 214.98%. In summary, it is feasible to prepare porous bone scaffolds for potential bone tissue engineering. This study shows the feasibility of applying textile structures to the field of tissue scaffolds and provides a new idea for the application structure of tissue engineering scaffolds.

GRAPHICAL AND ANALYTICAL DEFINITION OF PARAMETRIC CURVES IN EXPLICIT FORM

The aim of the work is to establish the relationship between graphical and analytical methods of solving problems on the example of the definition of parametric curves in explicit form. The idea is to represent the system of parametric equations of a plane curve in the space of Otxy coordinate system as a system of two projections of the curve on a complex Monge drawing. Then the desired curve can be obtained explicitly as a discrete set of points on the profile plane of projections in the Otxy coordinate system. If we consider the system of curve projections as a single curve in three-dimensional space Otxy, then this curve can be flat and spatial. For planar curves located in a partial position plane, it is easy to make the transition from parametric setting of the curve to an explicit form due to the linear relationship between one of the variables (x or y) and the parameter t. If the curve in the Otxy coordinate system belongs to the general position plane, we can use the projection plane replacement method to transform it to a projecting position. This allows a linear relationship to be established between one of the variables and a parameter to obtain the equation of the curve in explicit form, followed by an inverse transformation of the planes of projections. Mathematically, replacing the plane of projections is equivalent to replacing the coordinate system and reduces it to a rotation around the origin of the coordinates. Formulas for transforming the coordinate system, taking into account the peculiarities of using Monge's complex drawing and for determining the angle of rotation of the coordinate system are given.

4 Misinterpreting cognitive change over multiple timepoints: When practice effects meet age-related decline

Objective:Practice effects (PE) on cognitive testing impede our ability to accurately assess change. In particular, they hamper the detection of mild cognitive impairment (MCI) and progression to dementia by delaying the point at which test scores fall below diagnostic impairment cutoffs. When decline over time is expected, as with older adults or progressive diseases, failure to adequately address PEs may lead to inaccurate conclusions because PEs artificially boost scores while pathology-related or age-related decline reduces scores. The participant-replacement method accounts for PEs by comparing performance of demographically-matched replacement participants to returnees who have been tested previously. Unlike most methods, the participant-replacement method can separate pathology- or age-related decline from PEs; however, this method has only been used across two timepoints. Neuropsychologists tend to think that PEs level out after the first follow-up, but this issue has not been evaluated in models that allow PEs in the presence of overall decline. Including more than two timepoints makes it possible to determine if PEs level out after the first follow-up, but it is analytically challenging because individuals may not be assessed at every timepoint.Participants and Methods:We examined 1190 older adults in the Alzheimer’s Disease Neuroimaging Initiative who were cognitively unimpaired (n=809) or had MCI (n=381) at baseline. Participants completed six neuropsychological measures (Trails A, Trials B, Boston Naming Test, Category Fluency, Logical Memory, Rey Auditory Verbal Learning Task) at three timepoints (baseline, 12-month, 24-month). We implemented the participant-replacement method using generalized estimating equations in comparisons of matched returnees and replacements to calculate PEs. Propensity scores matched individuals on age, education, sex, and an estimate of premorbid functioning. Generalized estimating equations modeled PEs and age-related decline separately for each cognitive measure.Results:We observed significant PEs for 5 of the 6 measures in the cognitively unimpaired group and 4 measures in the baseline MCI group. PEs did not uniformly decrease across time; some—specifically on episodic memory measures—continued to increase beyond the first follow-up for both groups of participants. Without accounting for PEs, cognitive function appeared to improve or stay the same. In contrast, when PEs were included in the models, cognitive function appeared to decline or stay the same across time.Conclusions:The replacement method of PE adjustment revealed significant PEs across two follow-ups. PEs for episodic memory, in particular, did not level out, but actually increased after the first follow-up, two years after baseline. As expected in these older adults, accounting for PEs revealed cognitive decline, in some cases, even when PE-unadjusted scores improved. This method of assessing PEs, in turn, means earlier detection of cognitive deficits, including progression to MCI, and more accurate characterization of longitudinal change.

Construction of copper-based core-shell composite for efficient removal of xanthate from wastewater

As the most widely used flotation agent in mineral processing, xanthate in flotation wastewater causes significant damage to the environment and is a major obstacle to the construction of green mines. It is of great urgency to develop a low-cost, easy-to-separate and high-efficient adsorbent to remove xanthate from flotation wastewater. In this study, novel copper-based core-shell adsorbents with a large particle size are prepared by the hydrothermal crystallization-surface replacement method for xanthate removal. The as-prepared adsorbents were characterized by XRD, SEM-EDS, TEM, N2 adsorption-desorption, FTIR, XPS analyses. Because of the larger specific surface area and higher Cu element content on surface, CuO-based adsorbent (CuA-2) possesses a higher adsorption capacity and faster adsorption rate of potassium ethyl xanthate (KEX) when compared with Cu4(NO3)2(OH)6-based adsorbents (CuA-1). The removal percentage of 99% KEX can be obtained by adjusting dosage and the adsorption capacity is reduced by increasing solution pH due to the electrostatic repulsion. The maximum adsorption capacity of CuA-1 and CuA-2 are 645 and 1128 mg·g−1, respectively. The adsorption kinetic can be described by the pseudo-second-order model while the Langmuir adsorption isotherm is in good agreement with experimental results. EX- anion adsorbs and precipitates on the adsorbent in the form of flakes. A strong chemisorption of EX- anion occurs on the adsorbent surface, generating the Cu-xanthate complex. Moreover, the possible adsorption mechanism of KEX is proposed. The novel copper-based core-shell adsorbents show a promising application prospect in the treatment of flotation wastewater.

Type VI Secretion System Accessory Protein TagAB-5 Promotes Burkholderia pseudomallei Pathogenicity in Human Microglia.

Central nervous system (CNS) melioidosis caused by Burkholderia pseudomallei is being increasingly reported. Because of the high mortality associated with CNS melioidosis, understanding the underlying mechanism of B. pseudomallei pathogenesis in the CNS needs to be intensively investigated to develop better therapeutic strategies against this deadly disease. The type VI secretion system (T6SS) is a multiprotein machine that uses a spring-like mechanism to inject effectors into target cells to benefit the infection process. In this study, the role of the T6SS accessory protein TagAB-5 in B. pseudomallei pathogenicity was examined using the human microglial cell line HCM3, a unique resident immune cell of the CNS acting as a primary mediator of inflammation. We constructed B. pseudomallei tagAB-5 mutant and complementary strains by the markerless allele replacement method. The effects of tagAB-5 deletion on the pathogenicity of B. pseudomallei were studied by bacterial infection assays of HCM3 cells. Compared with the wild type, the tagAB-5 mutant exhibited defective pathogenic abilities in intracellular replication, multinucleated giant cell formation, and induction of cell damage. Additionally, infection by the tagAB-5 mutant elicited a decreased production of interleukin 8 (IL-8) in HCM3, suggesting that efficient pathogenicity of B. pseudomallei is required for IL-8 production in microglia. However, no significant differences in virulence in the Galleria mellonella model were observed between the tagAB-5 mutant and the wild type. Taken together, this study indicated that microglia might be an important intracellular niche for B. pseudomallei, particularly in CNS infection, and TagAB-5 confers B. pseudomallei pathogenicity in these cells.

Effect of refining slag compositions on its melting property and desulphurization

Abstract To investigate the feasibility of the refining slag with low fluoride, some oxides such as Al2O3, SiO2, B2O3, and Li2O were used to replace CaF2 in refining slag with the equivalent weight replacement method, and then the melting temperature and desulphurization capacity of slag were determined. The results show that the melting temperature of slag (CaF2 < 4 mass% and Al2O3 > 28 mass%) is less than 1,706 K, when CaF2 is substituted by Al2O3. This slag is able to decrease [S] in steel to less than 0.0060 mass%. In the case of substitution of CaF2 by SiO2, the melting temperature increases, while the desulphurization rate decreases. The fluxing action of B2O3 is stronger than that of CaF2, and the melting temperature decreases to 1,561 K when CaF2 is substituted by B2O3. Li2O can not only lower the melting temperature of slag but also improve the desulphurization rate.

Bone Tumour Sterilization Using Pasteurization for Autologous Bone Reconstruction

Primary bone malignancies have incidence of 0.2% among all malignant tumours and 15% in all primary tumours. The commonest primary bone malignancy is osteosarcoma which the frequency had increased by 0.3% yearly over the last decade. Improvement in treatment of bone sarcoma by multidisplinary protocols involving diagnostic imaging, chemotherapy and surgical technique has improved the survival rate from 20% to 80%, hence paradigm of treatment shifted from amputation to limb preserving surgery. Bone reconstruction techniques varies from prosthetic replacement, allograft and bone autograft method. Bone autograft method needed sterilizing technique to devitalised tumour cells and pasteurization is a good option in maintaining its biomorphogenic properties when heated to 60°C -70°C for 30-40 minutes. This article will be discussing on histopathology findings, biomechanical outcome and clinical outcome of bone reconstruction using pasteurized autograft bone method. The advantages of pasteurization include less risk of disease transmission, no risk of allogenic immunogenicity, readily available, simple, less expensive and satisfactory bone remodelling. However, in certain cases it also shows deteriorating outcome in long term follow up due to issues with graft fracture, infection and resorption.

Role of Computed Tomography before Transcatheter Pulmonary Valve Implantation in Patients with Dysfunctional Native Right Ventricular Outflow Tract.

The most performed percutaneous valve replacement procedure is for the aortic valve. In recent years, there have been developments in percutaneous valve replacement methods for other valves, including the pulmonary valve. Computed tomography plays a crucial role in various stages of procedure planning and provides essential information regarding potential complications after the procedure. We present images documenting step by step how to evaluate cardiac computed tomography in the qualification procedure for transcatheter pulmonary valve implantation in patients with dysfunctional native right ventricular outflow tract.

Generalized Estimator of Population Variance utilizing Auxiliary Information in Simple Random Sampling Scheme

In this study, using the Simple Random Sampling without Replacement (SRSWOR) method, we propose a generalized estimator of population variance of the primary variable. Up to the first order of approximation, the bias and Mean Squared Error (MSE) expressions for the suggested estimator are produced. The suggested estimator's characterizing scalar is optimized, and for this optimal value of the characterizing constant, the suggested estimator's least MSE is also determined. The efficiency criteria of the suggested estimator over the other estimators are determined after a theoretical comparison of the proposed estimator with the other population variance estimators that already exist. Several actual natural populations are used to validate these efficiency parameters. For practical use in various application domains, the estimator with the lowest MSE and the best Percentage Relative Efficiency (PRE) is advised.In this study, using the Simple Random Sampling without Replacement (SRSWOR) method, we propose a generalized estimator of population variance of the primary variable. Up to the first order of approximation, the bias and Mean Squared Error (MSE) expressions for the suggested estimator are produced. The suggested estimator's characterizing scalar is optimized, and for this optimal value of the characterizing constant, the suggested estimator's least MSE is also determined. The efficiency criteria of the suggested estimator over the other estimators are determined after a theoretical comparison of the proposed estimator with the other population variance estimators that already exist. Several actual natural populations are used to validate these efficiency parameters. For practical use in various application domains, the estimator with the lowest MSE and the best Percentage Relative Efficiency (PRE) is advised.In this study, using the Simple Random Sampling without Replacement (SRSWOR) method, we propose a generalized estimator of population variance of the primary variable. Up to the first order of approximation, the bias and Mean Squared Error (MSE) expressions for the suggested estimator are produced. The suggested estimator's characterizing scalar is optimized, and for this optimal value of the characterizing constant, the suggested estimator's least MSE is also determined. The efficiency criteria of the suggested estimator over the other estimators are determined after a theoretical comparison of the proposed estimator with the other population variance estimators that already exist. Several actual natural populations are used to validate these efficiency parameters. For practical use in various application domains, the estimator with the lowest MSE and the best Percentage Relative Efficiency (PRE) is advised.In this study, using the Simple Random Sampling without Replacement (SRSWOR) method, we propose a generalized estimator of population variance of the primary variable. Up to the first order of approximation, the bias and Mean Squared Error (MSE) expressions for the suggested estimator are produced. The suggested estimator's characterizing scalar is optimized, and for this optimal value of the characterizing constant, the suggested estimator's least MSE is also determined. The efficiency criteria of the suggested estimator over the other estimators are determined after a theoretical comparison of the proposed estimator with the other population variance estimators that already exist. Several actual natural populations are used to validate these efficiency parameters. For practical use in various application domains, the estimator with the lowest MSE and the best Percentage Relative Efficiency (PRE) is advised.In this study, using the Simple Random Sampling without Replacement (SRSWOR) method, we propose a generalized estimator of population variance of the primary variable. Up to the first order of approximation, the bias and Mean Squared Error (MSE) expressions for the suggested estimator are produced. The suggested estimator's characterizing scalar is optimized, and for this optimal value of the characterizing constant, the suggested estimator's least MSE is also determined. The efficiency criteria of the suggested estimator over the other estimators are determined after a theoretical comparison of the proposed estimator with the other population variance estimators that already exist. Several actual natural populations are used to validate these efficiency parameters. For practical use in various application domains, the estimator with the lowest MSE and the best Percentage Relative Efficiency (PRE) is advised.In this study, using the Simple Random Sampling without Replacement (SRSWOR) method, we propose a generalized estimator of population variance of the primary variable. Up to the first order of approximation, the bias and Mean Squared Error (MSE) expressions for the suggested estimator are produced. The suggested estimator's characterizing scalar is optimized, and for this optimal value of the characterizing constant, the suggested estimator's least MSE is also determined. The efficiency criteria of the suggested estimator over the other estimators are determined after a theoretical comparison of the proposed estimator with the other population variance estimators that already exist. Several actual natural populations are used to validate these efficiency parameters. For practical use in various application domains, the estimator with the lowest MSE and the best Percentage Relative Efficiency (PRE) is advised.

High efficiency and selective separation of oily wastewater based on superamphiphilic biomass aerogel: Characteristics, mechanisms and application

The design and development of multifunctional materials to meet the sophisticated requirements of oily wastewater treatment is an urgent need and remains a great challenge. Herein, a superamphiphilic bio-aerogel (PTGA) with honeycomb-like porous structure was synthesized. The directional and reversible control of interfacial wettability can be achieved by simple pre-wetting process and solvent replacement method. Combined with the advantages of structure and wettability, PTGA was proved to be ideal for high-efficient oil-water mixture separation (J> 1500 L/m2·h, η > 99.8%), oils absorption (Cabs = 17–26 g/g) and dye selective removal (MO: 73.552 mg/g, MB: 45.876 mg/g). Furthermore, based on the newly developed dynamic separation device and excellent mechanical property of PTGA, enhanced separation of oil-water mixture (J = 3007 L/m2·h) and synergistic removal of co-existing pollutants (MB: 51.274 mg/g) were realized. Mechanism results indicated that the transition of interfacial wetting properties of PTGA was a multi-stage process, while oil/water separation and dye adsorption were two independent processes. Benefit from facile synthesis and unparalleled characteristics, the designed PTGA promise to be reliable and competitive candidates in wastewater remediation.

Crystal Structure and Sequence Analysis of N5, N10-Methylenetetrahydrofolate Dehydrogenase/Cyclohydrolase Enzyme from Porphyromonas gingivalis

The methylenetetrahydrofolate dehydrogenase–cyclohydrolase (FolD) enzyme has a dual activity of N5,N10-methylenetetrahydrofolate dehydrogenase and cyclohydrolase. This enzyme plays a critical role in the chemical modification of tetrahydrofolate, which is an important coenzyme involved in the synthesis of DNA, RNA, and amino acids. Therefore, bacterial FolD has been studied as a potential drug target for the development of antibiotics. Here, we determined the crystal structure of FolD (PgFolD) from the oral pathogen Porphyromonas gingivalis at 2.05 Å resolution using the molecular replacement method. The crystal structure of PgFolD was successfully refined to a crystallographic R-factor of 21.4% (Rfree = 23.8%). The crystals belong to the space group of P4322 with the unit cell parameters of a = 110.7 Å, b = 110.7 Å, and c = 69.8 Å, containing one subunit in the asymmetric unit. Our analytical size-exclusion chromatography results indicated that PgFolD forms a stable dimer in solution. Additionally, structural and sequence comparison studies with previously known FolDs revealed that PgFolD has a different substrate-binding site residue composition. These findings provide valuable insights for the structure-based development of specific inhibitors against the Porphyromonas gingivalis pathogen.

Spectral composition of LED light differentially affects biomass, photosynthesis, nutrient profile, and foliar nitrate accumulation of lettuce grown under various replacement methods of nutrient solution.

To enhance crop yield and quality, plant cultivation in controlled-growing systems is an alternative to traditional open-field farming. The use of light-emitting diode (LED) as an adjustable light source represents a promising approach to improve plant growth, metabolism, and function. The objective of this study was to assess the impact of different light spectra (red, red/blue (3:1), blue, and white) with an emission peak of around 656, 656, 450, and 449 nm, respectively, under various replacement methods of nutrient solution (complete replacement (CR), EC-based replacement (ECBR), and replacing based on plant needs (RBPN)), on biomass, physiological traits, and macro- and micronutrient contents of two best-known lettuce varieties, Lollo Rossa (LR) and Lollo Bionda (LB), in the nutrient film technique (NFT) hydroponic system. The results indicated that mix of red and blue LED spectra under RBPN method is the most effective treatment to enhance fresh and dry weights of lettuce plants. In addition, red LED spectrum under RBPN, and red and blue light under ECBR nutrient solution significantly increased leaf stomatal conductance, net photosynthesis and transpiration rate, and intercellular CO2 concentration of LR variety. Phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mn) content in LR variety, and iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) content in both varieties increased upon exposure to blue and red LED light spectrum with RBPN method. Our results suggest that exposure to combination of red and blue light along with feeding plants using RBPN and ECBR methods can increase absorption of macro- and micronutrient elements and improve photosynthetic properties, and eventually increase lettuce yield with lower nitrate accumulation.

Molecular characteristics of some Botrytis isolates and antagonistic activity of Bacillus subtilis and its bacteriocin on tomato fruit

Gray mold, caused by Botrytis cinerea, is one of the most devastating agricultural diseases during the pre and postharvest stages. This study aims to investigate the application of Bacillus subtilis as a bioagent against B. cinerea and reducing pre and postharvest disease as a replacement method to chemical pesticides. Five Botrytis isolates were molecularly confirmed and the virulent isolate BC2 was registered for the first time in the National Center of Biotechnology Information (NCBI) with accession number OP257237. The mycelial growth of B. cinerea was inhibited by up to 84% when treated with the bio agent bacterium using the double drawing method in Petri plates. Pre-harvest application of B. subtilis at a concentration of 108/ml CFU reduced postharvest -gray mold of tomato fruit during ripening stages in the greenhouse. Preharvest application of bioagent bacterium B. subtilis induced the levels of B-1, 3-glucanase and Polyphenol oxidase, indicating enhanced plant resistance to gray mold. Disease severity was decreased compared with control and extended the shelf life at 25 °C.The field application of the bio agent bacterium at the maturity of ripening in preharvest had a significant effect on increasing the level of polyphenol oxidase PPO and B-1, 3-glucanase, which are related to the enhancement of plant defenses and resistance. Additionally, it led to an increase in storage life and a reduction in post-harvest losses. The results demonstrated that preharvest application of bio agent bacterium Bacillus subtilis improved the quality of postharvest tomato fruit and significantly reduced gray mold incidence, all without the use of chemical pesticides.

Decision-Making Framework for Medical Equipment Maintenance and Replacement in Private Hospitals

The process for medical equipment maintenance and replacement in hospitals is a challenging and demanding procedure. Further, the topic of making decisions to maintain or replace or upgrade medical equipment has been debated for a long time since errors equipment maintenance will increase equipment failure at undesirable times; or if early equipment replacement will result in high investment costs and premature disposal. Therefore, standard operating procedures or guidelines need to be in place to help healthcare facilities conduct a more organized and planned maintenance and replacement process. Many hospitals may already have established replacement guidelines or have implemented asset monitoring systems for this purpose. However, the effectiveness of this system has not yet been systematically evaluated. Several studies have been conducted on the same research topic, but most of the findings emphasize the replacement method rather than the criteria that contributed to the decision. Criteria for replacing medical equipment play an important role in ensuring that the equipment can be used cost-effectively. Thus, this research aims to identify important criteria that need to be considered for medical equipment maintenance and replacement focusing on private hospitals. This research was conducted in three phases: (1) a structured literature review; (2) semi-structured interviews with eleven (11) healthcare experts; and (3) a pairwise comparison survey with 50 biomedical engineers. A decision-making framework was developed based on the findings of these three research phases. The framework developed will provide guidelines for practitioners and academics to understand and make better decisions for medical equipment maintenance and replacement in the context of private hospitals.

Steady-state solutions for a reaction–diffusion equation with Robin boundary conditions: Application to the control of dengue vectors

AbstractIn this paper, we investigate an initial-boundary value problem of a reaction–diffusion equation in a bounded domain with a Robin boundary condition and introduce some particular parameters to consider the non-zero flux on the boundary. This problem arises in the study of mosquito populations under the intervention of the population replacement method, where the boundary condition takes into account the inflow and outflow of individuals through the boundary. Using phase plane analysis, the present paper studies the existence and properties of non-constant steady-state solutions depending on several parameters. Then, we prove some sufficient conditions for their stability. We show that the long-time efficiency of this control method depends strongly on the size of the treated zone and the migration rate. To illustrate these theoretical results, we provide some numerical simulations in the framework of mosquito population control.

Bone Defect Replacement in Diabetic Neuropathic Osteoarthropathy (Charcot Foot): Review

Background. The number of patients with diabetes mellitus, including those with its severe complications such as Charcot neuropathic osteoarthropathy, is increasing worldwide. Restoration of weight bearing ability and creation of conditions for ulcer healing is challenging for trauma and orthopedic surgeons, especially because of the need to restore bone tissue defects.
 Aim of the review to compare modern methods of replacement of large bone tissue defects of the distal segment of the lower limb in patients with Charcot neuropathic osteoarthropathy.
 Methods. The articles were searched in PubMed/MEDLINE, Google Scholar, Scopus, eLIBRARY, CyberLeninka databases. The search was performed using the following keywords and word combinations: Charcot foot, diabetic neuropathic osteoarthropathy and bone grafting. Full-text articles in Russian and English were selected. The search was carried out without chronological limitations due to the small number of published studies and specific subject of research.
 Results. The possibilities of bone defect replacement in Charcot foot are poorly described in the world literature. The narrow specificity and relative infrequency of this pathology is the probable reason for the small number of publications and the lack of studies with a high level of evidence.
 Conclusion. Bone autografting for lesions of the medial or lateral midfoot column and Ilizarov tibial lengthening to compensate for limb shortening after reconstructive surgeries at the level of the hindfoot and ankle joint are the most commonly used methods of bone defect replacement in patients with Charcot foot. Free bone autografting (possibly with demineralized bone matrix) is the method of choice for small defects of the lateral or medial column of the midfoot.

Revision Anterior Cruciate Ligament Reconstruction: Current Approaches to Preoperative Planning (Systematic Review)

Background. The number of primary anterior cruciate ligament (ACL) reconstructions increases every year, which causes an increase in revision interventions due to ACL graft failure. When studying the literature, we identify many factors that together influence the outcome of revision ACL reconstruction, but are not always taken into account by surgeons.
 Aim of the review — is to perform a systematic review of studies that evaluated the outcomes of revision anterior cruciate ligament reconstructions and to identify optimal solutions to the most common problems encountered in preoperative planning.
 Methods. Information search was performed in the eLIBRARY, PubMed, and Scopus databases for the period from 2013 to 2022. Studies describing the main aspects of revision ACL reconstruction were selected for analysis. Inclusion criteria were the following: mean patient follow-up period of no less than 12 months, number of observations of no less than 10 cases. After evaluation of 898 articles, 22 articles were included in the systematic review.
 Results. Five main factors that should be taken into account in preoperative planning of revision ACL reconstruction have been identified: choice of the graft, necessity of reconstruction of the anterolateral complex, correction of tibial plateau deformity in the sagittal plane, determination of indications for one- or two-stage intervention, method of bone defect replacement in two-stage surgical treatment.
 Conclusion. The patient’s autogenous tissues should be preferred when choosing a graft. Correction of excessive anteroposterior tibial plateau inclination angle is performed only at the second revision intervention if the inclination angle exceeds 12º. Reconstruction of the anterolateral complex should be performed in young, active patients who are involved in pivot sports and in case of severe anterior instability. When determining the possibility of performing revision ACL reconstruction in one or two stages, the canal diameter is not a crucial parameter, as it is necessary to take into account the possibility of fusion of the canals from the previous surgery with the newly created ones. If the canals have correct entry points, one-stage revision reconstruction can be performed with the canal width not exceeding 10 mm and depending on the expected diameter and type of the prepared tendon graft. Bone grafting of the secondary dilated canals in two-stage intervention can be carried out using any material, but allogenous bone or synthetic grafts have certain advantages.