孟鲁司特钠联合布地奈德混悬液对哮喘急性发作患儿血清EOS、ECP水平和肺功能的影响

目的:探索孟鲁司特钠联合布地奈德混悬液对哮喘急性发作患儿血清嗜酸性粒细胞(EOS)、嗜酸性粒细胞阳离子蛋白(ECP)水平和肺功能的影响。方法:选择自2015年10月至2016年10月我院收治的200例支气管哮喘急性发作患儿,按照随机数表法分成观察组和对照组各100例。对照组患儿口服孟鲁司特钠,观察组患儿在对照组基础上给予布地奈德气雾剂进行雾化治疗,两组均治疗1周。统计分析两组患儿的临床有效率,肺功能指标,包括第1秒用力呼气容积(FEV1)、用力肺活量(FVC)及FEV1/FVC,对比治疗前后两组患儿血清中EOS、ECP水平的变化。结果:治疗后,观察组的总有效率为97.00%,显著高于对照组的81.00%(P0.05);经治疗后两组患儿肺功能指标均较治疗前明显改善,且观察组患儿优于对照组(P0.05);两组患儿治疗后EOS、ECP水平均低于治疗前,而观察组患儿低于对照组,差异均有统计学意义(P0.05)。结论:孟鲁司特钠联合布地奈德对于小儿哮喘的急性发作具有良好的临床疗效,能显著改善患儿肺功能和血清中炎症因子的水平,减轻患儿体内的炎症反应,值得在临床上推广应用。     

Sodium bicarbonate‐gelled chitosan beads as mechanically stable carriers for the covalent immobilization of enzymes

The poor mechanical stability of chitosan has long impeded its industrial utilization as an immobilization carrier. In this study, the mechanical properties of chitosan beads were greatly improved through utilizing the slow rate of the sodium bicarbonate‐induced chitosan gelation and combining it with the chemical cross‐linking action of glutaraldehyde (GA). The GA‐treated sodium bicarbonate‐gelled chitosan beads exhibited much better mechanical properties and up to 2.45‐fold higher observed activity of the immobilized enzyme (β‐D‐galactosidase (β‐gal)) when compared to the GA‐treated sodium tripolyphosphate (TPP)‐gelled chitosan beads. The differences between the sodium bicarbonate‐gelled and the TPP‐gelled chitosan beads were proven visually and also via scanning electron microscopy, elemental analysis, and differential scanning calorimetry. Moreover, the optimum pH, the optimum temperature, the apparent K_m, and the apparent V_max of the β‐gals immobilized onto the two aforementioned types of chitosan beads were determined and compared. A reusability study was also performed. This study proved the superiority of the sodium bicarbonate‐gelled chitosan beads as they retained 72.22 ± 4.57% of their initial observed activity during the 13^th reusability cycle whereas the TPP‐gelled beads lost their activity during the first four reusability cycles, owing to their fragmentation. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:347–361, 2018     

Reactive cysteine residues in the oxidative dimerization and Cu2+ induced aggregation of human γD-crystallin: Implications for age-related cataract

Cysteine (Cys) residues are major causes of crystallin disulfide formation and aggregation in aging and cataractous human lenses. We recently found that disulfide linkages are highly and partly conserved in β- and γ-crystallins, respectively, in human age-related nuclear cataract and glutathione depleted LEGSKO mouse lenses, and could be mimicked by in vitro oxidation. Here we determined which Cys residues are involved in disulfide-mediated crosslinking of recombinant human γD-crystallin (hγD). In vitro diamide oxidation revealed dimer formation by SDS-PAGE and LC-MS analysis with Cys 111-111 and C111-C19 as intermolecular disulfides and Cys 111-109 as intramolecular sites. Mutation of Cys111 to alanine completely abolished dimerization. Addition of αB-crystallin was unable to protect Cys 111 from dimerization. However, Cu²⁺-induced hγD-crystallin aggregation was suppressed up to 50% and 80% by mutants C109A and C111A, respectively, as well as by total glutathionylation. In contrast to our recently published results using ICAT-labeling method, manual mining of the same database confirmed the specific involvement of Cys111 in disulfides with no free Cys111 detectable in γD-crystallin from old and cataractous human lenses. Surface accessibility studies show that Cys111 in hγD is the most exposed Cys residue (29%), explaining thereby its high propensity toward oxidation and polymerization in the aging lens.     

Natural products as modulators of the nuclear receptors and metabolic sensors LXR,FXR and RXR

Nuclear receptors (NRs) represent attractive targets for the treatment of metabolic syndrome-related diseases. In addition, natural products are an interesting pool of potential ligands since they have been refined under evolutionary pressure to interact with proteins or other biological targets.This review aims to briefly summarize current basic knowledge regarding the liver X (LXR) and farnesoid X receptors (FXR) that form permissive heterodimers with retinoid X receptors (RXR). Natural product-based ligands for these receptors are summarized and the potential of LXR, FXR and RXR as targets in precision medicine is discussed.     

Plasma N-glycome composition associates with chronic low back pain

Background

Low back pain (LBP) is the symptom of a group of syndromes with heterogeneous underlying mechanisms and molecular pathologies, making treatment selection and patient prognosis very challenging. Moreover, symptoms and prognosis of LBP are influenced by age, gender, occupation, habits, and psychological factors. LBP may be characterized by an underlying inflammatory process. Previous studies indicated a connection between inflammatory response and total plasma N-glycosylation. We wanted to identify potential changes in total plasma N-glycosylation pattern connected with chronic low back pain (CLBP), which could give an insight into the pathogenic mechanisms of the disease.

Identification of Amino Acid Residues in the α, β, and γ Subunits of the Epithelial Sodium Channel (ENaC) Involved in Amiloride Block and Ion Permeation

The amiloride-sensitive epithelial Nachannel (ENaC) is a heteromultimeric channel made of three αβγ subunits. The structures involved in the ion permeation pathway have only been partially identified, and the respective contributions of each subunit in the formation of the conduction pore has not yet been established. Using a site-directed mutagenesis approach, we have identified in a short segment preceding the second membrane-spanning domain (the pre-M2 segment) amino acid residues involved in ion permeation and critical for channel block by amiloride. Cys substitutions of Gly residues in β and γ subunits at position βG525 and γG537 increased the apparent inhibitory constant (K _i) for amiloride by >1,000-fold and decreased channel unitary current without affecting ion selectivity. The corresponding mutation S583 to C in the α subunit increased amiloride K _i by 20-fold, without changing channel conducting properties. Coexpression of these mutated αβγ subunits resulted in a nonconducting channel expressed at the cell surface. Finally, these Cys substitutions increased channel affinity for block by externalZn²⁺ ions, in particular the αS583C mutant showing a K _i for Zn²⁺of 29 μM. Mutations of residues αW582L or βG522D also increased amiloride K _i, the later mutation generating a Ca²⁺blocking site located 15% within the membrane electric field. These experiments provide strong evidence that αβγ ENaCs are pore-forming subunits involved in ion permeation through the channel. The pre-M2 segment of αβγ subunits may form a pore loop structure at the extracellular face of the channel, where amiloride binds within the channel lumen. We propose that amiloride interacts with Na⁺ions at an external Na⁺binding site preventing ion permeation through the channel pore.     

Anomalous Effect of Permeant Ion Concentration on Peak Open Probability of Cardiac Na+ Channels

Human heart Na⁺ channels were expressed transiently in both mammalian cells and Xenopus oocytes, and Na⁺ currents measured using 150 mM intracellular Na⁺. Decreasing extracellular permeant ion concentration decreases outward Na⁺ current at positive voltages while increasing the driving force for the current. This anomalous effect of permeant ion concentration, especially obvious in a mutant (F1485Q) in which fast inactivation is partially abolished, is due to an alteration of open probability. The effect is only observed when a highly permeant cation (Na⁺, Li⁺, or hydrazinium) is substituted for a relatively impermeant cation (K⁺, Rb⁺, Cs⁺, N -methylglucamine, Tris, choline, or tetramethylammonium). With high concentrations of extracellular permeant cations, the peak open probability of Na⁺ channels increases with depolarization and then saturates at positive voltages. By contrast, with low concentrations of permeant ions, the open probability reaches a maximum at approximately 0 mV and then decreases with further depolarization. There is little effect of permeant ion concentration on activation kinetics at depolarized voltages. Furthermore, the lowered open probability caused by a brief depolarization to +60 mV recovers within 5 ms upon repolarization to −140 mV, indicative of a gating process with rapid kinetics. Tail currents at reduced temperatures reveal the rapid onset of this gating process during a large depolarization. A large depolarization may drive a permeant cation out of a site within the extracellular mouth of the pore, reducing the efficiency with which the channel opens.