人类少突胶质细胞在髓鞘修复中的作用

有关髓鞘和少突胶质细胞的研究大部分与脱髓鞘疾病相关,如多发性硬化、脑白质营养不良或脊髓损伤。髓鞘慢性脱失,慢慢导致神经退行性变,最终导致永久而严重的神经功能丧失。因此,尽快恢复髓鞘是修复脱髓鞘疾病的最有效方法。移植外源性的髓鞘再生细胞是一个有希望的治疗方法。已有多项在体和离体实验将各种具有髓鞘形成功能细胞(少突胶质细胞、施万细胞、嗅鞘细胞等)进行移植,观察其髓鞘修复功能。本综述对将人类少突胶质细胞用于治疗脱髓鞘疾病的相关研究进行总结。首先,对人类少突胶质细胞从胚胎发育晚期到产后早期的发育过程进行简要的综述。然后,对各种内源性和外源性的少突胶质细胞调节因子的研究进行总结。在离体实验中,必须调控好各种调节因子才能使培养的少突胶质细胞达到足够的数量用于移植。之后,探讨了人类少突胶质细胞的可能来源,包括一些新型的少突胶质细胞生产策略,如诱导多能干细胞诱导直接分化为少突胶质细胞。最后,本综述对人类少突胶质细胞的髓鞘再生功能和效率进行了系统的回顾。     

Mechanical Properties of Different Nanopatterned TiO2 Substrates and Their Effect on Hydrothermally Synthesized Bioactive Hydroxyapatite Coatings

Nanotechnology is a very attractive tool for tailoring the surface of an orthopedic implant to optimize its interaction with the biological environment. Nanostructured interfaces are promising, especially for orthopedic applications. They can not only improve osseointegration between the implant and the living bone but also may be used as drug delivery platforms. The nanoporous structure can be used as a drug carrier to the surrounding tissue, with the intention to accelerate tissue–implant integration as well as to reduce and treat bacterial infections occurring after implantation. Titanium oxide nanotubes are promising for such applications; however, their brittle nature could be a significantly limiting factor. In this work, we modified the topography of commercially used titanium foil by the anodization process and hydrothermal treatment. As a result, we obtained a crystalline nanoporous u-shaped structure (US) of anodized titanium oxide with improved resistance to scratch compared to TiO₂ nanotubes. The US titanium substrate was successfully modified with hydroxyapatite coating and investigated for bioactivity. Results showed high bioactivity in simulated body fluid (SBF) after two weeks of incubation.     

Strength Properties of a Porous Titanium Alloy Ti6Al4V with Diamond Structure Obtained by Laser Power Bed Fusion (LPBF)

This paper presents the results of experimental research on the strength properties of porous structures with different degrees of density manufactured of Ti6Al4V titanium alloy by Laser Power Bed Fusion. In the experiment, samples with diamond structure of porosity: 34%, 50%, 73% and 81% were used, as well as samples with near-zero porosity. Monotonic tensile tests were carried out to determine the effective values of axial modulus of elasticity, ultimate tensile strength, offset yield strength, ultimate elongation and Poisson ratio for titanium alloys with different porosities. The paper also proposes relationships that can be easily used to estimate the strength and rigidity of a porous material manufactured by 3D printing. They were obtained by the approximation of two quotients. The first one refers to the relationship between the tensile strength of a material with a defined porosity to the strength of full-filled material. The second similarly determines the change in the value of the axial modulus of elasticity. The analysis of microscopic observations of fracture surfaces and also microtomography visualization of the material structure are also presented.     

Influence of the Selected Physical Modifier on the Dynamical Behavior of the Polymer Composites Used in the Aviation Industry

In this research, an analysis of polymer composite with the matrix of L285-cured hardener H286 and six reinforcement layers of carbon fabric GG 280 T was provided. It involved a comparison of the dynamical behavior responses for three cases of composite structures in the context of the presence of the mass share modifier. The samples with the addition of a physical modifier with varying mass percentages were investigated by being subjected to dynamic tests with specific parameters, i.e., constant excitation amplitude and vibration frequency in the vicinity of the base resonance zone. The analysis allowed for indicating the relationship between the composition of the prepared composites and their dynamic response via stiffness characteristics. In addition, the investigation resulted in determining the range of harmful dynamical operating conditions, which may contribute to damage to the composite structures.     

Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound

We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd_0.4Tb_0.6Co₂ compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔS_M) was determined for many values of the magnetic field change (Δμ₀H), which varied from 0.1 to 7 T. In each case, the ΔS_M had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (J_RR), R-Co (J_RCo), and Co-Co (J_CoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near T_C the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.     

Volumetric growth of the lungs in human fetuses: an anatomical,hydrostatic and statistical study

Purpose

The prenatal assessment of lung volume is becoming increasingly important in determining survival in both preterm infants and newborns affected by pulmonary hypoplasia. This study aimed to examine the lung volumes in the human fetus at varying gestational ages.

Materials and methods

Using anatomical, hydrostatic (water displacement according to Archimedes’ patent) and statistical methods (one-way ANOVA test for paired data and post-hoc Bonferroni test, Kolmogorov–Smirnov test, Levene’s test, Student’s t test, regression analysis), volumes of the right and left lungs were measured in 67 human fetuses of both sexes (35 males, 32 females) aged 16–25 weeks, derived from spontaneous abortions and stillbirths.

Results

No male–female differences concerning the right and left pulmonary volumes were found. The mean volume of the right lung increased from 1.43 ± 0.25 to 8.45 ± 2.66 cm³, according to the cubic function y = –1.592 + 0.0007 × age³ ± 0.851 (R ² = 0.84). The volumetric growth of the left lung, from 1.24 ± 0.22 to 6.78 ± 3.03 cm³, followed the cubic model y = –1.110 + 0.0005 × age³ ± 0.794 (R ² = 0.78). The total pulmonary volume increased from 2.67 ± 0.47 to 15.22 ± 5.58 cm³, in accordance with the cubic model y = –2.729 + 0.0012 × age³ ± 1.598 (R ² = 0.83). The mean volumes of the right and left lungs accounted for 54.9 ± 2.0 and 45.1 ± 2.0 %, respectively, of the total lung volume.

Conclusions

No sex differences are found between the lung volumes in the fetus. The growth of fetal lung volume follows a three-degree polynomial function. Throughout the analyzed period the two lungs grow proportionately to each other, with the volumetric predominance of the right lung. The lung volumes in the fetus are of great relevance in the evaluation of the normal pulmonary growth and the diagnosis of pulmonary hypoplasia.     

B‐cell modulation of dendritic‐cell function: Signals from the far side

An appropriate immune response against a specific pathogen requires finely orchestrated interactions between the various cell populations within the immune system. At the same time, immunological tolerance to self must be maintained. DCs play an essential role in achieving these dual requisites. They coordinate adaptive immunity by integrating signals directly emanating from both infectious agents and cells of the immune system. Many such signals, especially those from innate cells and T cells, have been extensively characterized. In contrast, little is known about how B cells modulate function of DCs. B cells produce a variety of cytokines, including IL‐10 and IL‐6, which are known to influence DC function. In addition, Igs constitute the major secretory products of terminally differentiated B cells (plasma cells). DCs express various types of receptors for binding Ig, such as Fc receptors and C‐type lectin receptors. In accordance, Igs can regulate DC function depending on the receptors engaged. Here, we review the emerging immunomodulatory role of cytokines and Ig secreted by B cells. We discuss the evidence for how these B‐cell‐derived factors may shape the adaptive immune response by directly acting on DCs.     

Tissue Repair and Fibrosis

Background

Because antileukotrienes may inhibit inflammation, it is plausible that montelukast administered for a long time could suppress skin wheal and flare reaction, and thus, it should be discarded prior to the tests. This study assessed the effect of long-lasting treatment with montelukast alone or in combination with antihistamines on wheal and flare in skin pricks tests (SPT) in patients sensitized to perennial allergens.

Methods

We conducted a 32-week, double-blind, placebo-controlled, cross-over and randomized trial that implicated two arms: arm A, 20 patients received levocetirizine, montelukast with or without levocetirizine or placebo; arm B, 20 patients received desloratadine, montelukast with or without desloratadine or placebo. All treatment periods lasted 6 weeks and were separated by 2-week washouts. At baseline and on the last day of each treatment period, SPT were performed in all participants.

Results

Both levocetirizine and desloratadine in monotherapy, or in combination with montelukast, were effective in reducing wheal and flare in SPT. Monotherapy with montelukast did not change the size of the wheal for either histamine or for house dust mites, in either arm of the study, but significantly reduced the size of flare for histamine in arm A. Addition of montelukast to antihistamine did not exceed efficacy of monotherapy with antihistamine in both arms of the study.

Conclusions

Since the size of wheal determines the results of SPT, montelukast, even taken for a long time, does not have to be discarded prior to the tests.     

Characteristics of metabolic stability and the cell permeability of 2‐pyrimidinyl‐piperazinyl‐alkyl derivatives of 1H‐imidazo[2,1‐f]purine‐2,4(3H,8H)‐dione with antidepressant‐ and anxiolytic‐like activities

A series of 2‐pyrimidinyl‐piperazinyl‐alkyl derivatives of 1H‐imidazo[2,1‐f]purine‐2,4(3H,8H)‐dione has been synthesized in an attempt to discover a new class of psychotropic agents. Compounds were evaluated for their in vitro affinity for serotonin 5‐HT_1A, 5‐HT₇, and phosphodiesterases PDE4 and PDE10. The most potent compound 2‐pyrimidinyl‐1‐piperazinyl‐butyl‐imidazo[2,1‐f]purine‐2,4‐dione ( 4b ) behaved as strong and selective antagonist of 5‐HT_1A. Molecular modeling studies revealed differences in binding mode between compound 4b and buspirone, which might reflect variation of the ligands’ affinity and potency in the 5‐HT_1A receptor. Compound 4b in silico models demonstrated drug‐likeness properties and, contrary to buspirone, showed a metabolic stability in mouse liver microsomes system. Experimentally obtained value of apparent permeability coefficient P_app for 4b in parallel artificial permeability assay indicates the possibility of binding weakly to plasma proteins and high intestinal absorption fraction. Evaluation of the antidepressant‐ and anxiolytic‐like activities of 4b revealed both activities at the same dose of 1.25 mg/kg and seemed to be specific. The antidepressant and/or anxiolytic properties of 4b may be related to its first‐pass effect.