Single-Molecule Exchange inside a Nanocage Provides Insights into the Origin of π-π Interactions.

The attractive interactions between aromatic rings, also known as π-π interactions, have been widely used for decades. However, the origin of π-π interactions remains controversial due to the difficulties in experimentally measuring the weak interactions between π-systems. Here, we construct an elaborate system to accurately compare the strength of the π-π interactions between phenylalanine derivatives via molecular exchange processes inside a protein nanopore. Based on quantitative comparison of binding strength, we find that in most cases, the π-π interaction is primarily driven by dispersive attraction, with the electrostatic interaction playing a secondary role and tending to be repulsive. However, in cases where electronic effects are particularly strong, electrostatic induction may exceed dispersion forces to become the primary driving force for interactions between π-systems. The results of this study not only deepen our understanding of π-stacking but also have potential implications in areas where π-π interactions play a crucial role.

Clinical effect of combination of octreotide and omeprazole in children with acute upper gastrointestinal bleeding and the levels of serum creatinine and serum urea nitrogen.

Pediatric upper gastrointestinal bleeding refers to an acute massive hemorrhage of the upper digestive tract and biliary tract, which is a common clinical emergency in pediatrics. This study aimed to evaluate the clinical effect of octreotide combined with omeprazole in pediatric upper gastrointestinal bleeding. Totally 84 cases of pediatric upper gastrointestinal bleeding admitted to Ningbo Women and Children's Hospital from November 2019 to April 2021 were divided into groups according to the admission order. The control group received omeprazole treatment and the observation group received octreotide plus. The total clinical effective rate of children in the observation group was higher than that of the control group. The observation group was superior to the control group with respect to the average hemostasis time, hemostasis rate, rebleeding rate and length of stay after treatment. The observation group witnessed a significantly better quality of life than the control group. For children with acute upper gastrointestinal bleeding, the combination of omeprazole and octreotide yields a promising effect in the adjustment of blood creatinine and serum urea nitrogen levels and hemostasis, which is worthy of clinical application.

Correction: A bifunctional DNA probe for sensing pH and microRNA using a nanopore.

Correction for 'A bifunctional DNA probe for sensing pH and microRNA using a nanopore' by Yun Zhang et al., Analyst, 2020, 145, 7025-7029, DOI: 10.1039/D0AN01208D.

A bifunctional DNA probe for sensing pH and microRNA using a nanopore.

We have developed a bifunctional probe based on triplex molecular beacons for the measurement of environmental pH and quantification of microRNA-10b using a nanopore. The probe responds sharply to solution pH changes in the range of 6.0-7.5. The limit of detection for microRNA-10b is as low as 5.0 pM.

Influence of riboflavin on the oxidation kinetics of unsaturated fatty acids at the air/aqueous interface revealed by sum frequency generation vibrational spectroscopy.

Riboflavin, a common nutrient also known as vitamin B2, is known to potentially play important roles in preventing lipid peroxidations. However, the detailed antioxidant mechanisms, especially the influence of riboflavin on lipid oxidations at biological interfaces, have not yet been fully explored. In the current study, the effect of riboflavin molecules on the oxidation kinetics of monounsaturated cis-11-eicosenoic acid (EA) at the air/water interface was systematically investigated using sum frequency generation vibrational spectroscopy (SFG-VS). It was discovered that the oxidation rates of the interfacial EA molecules can be reduced by about two to three times in the presence of riboflavin in the aqueous subphase. Further SFG-VS measurements under the protection of nitrogen purging gas showed that more tightly packed and ordered monolayer structures were formed by the surface adsorption of riboflavin molecules, making the C[double bond, length as m-dash]C bonds less accessible to the gas phase oxidative species. These results suggested that the antioxidant mechanism for riboflavin in the vicinity of biomembranes may not necessarily involve other reducing agents. They also show the great importance of interfacial molecular structures in biologically relevant chemical reactions.

Clinical Effect of Standardized Dietary Avoidance Therapy on Children with Milk Protein Allergy and Its Effect on Intestinal Flora.

Objective: The aim of this study is to analyze the clinical effect of standardized dietary avoidance therapy on children with cow milk protein allergy (CMPA) and its effect on the intestinal flora. Methods: The clinical data of 200 children with CMPA from our hospital from February 2020 to May 2021 were collected, and they were divided into a study group (n = 100) and a routine group (n = 100) based on different intervention modalities. The routine group received routine treatment, whereas the standardized dietary avoidance therapy was used in the study group. The clinical effects and related intestinal microflora indexes of the two groups were analyzed and compared. Results: There was no significant difference in the incidence of related symptoms between the two groups before intervention (P > 0.05), and the conditions of the two groups were improved after intervention. The incidences of skin (2%), digestive tract (3.00%), and respiratory tract (1.00%) in the study group were significantly lower than those in the routine group (14.00%, 18.00%, and 11.00%) (P > 0.05). The time taken for complete remission of symptoms and milk tolerance months in the study group (41.23 ± 23.68, 13.28 ± 6.17) were significantly shorter than those in the routine group (145.14 ± 66.74, 16.17 ± 8.05) (P > 0.05). The values of height, weight, and head circumference (HC) of children in the study group (79.88 ± 2.18, 11.09 ± 1.34, 47.88 ± 0.63) were higher than those in the routine group (76.21 ± 2.34, 9.81 ± 1.18, 45.98 ± 0.59) (P > 0.05). The levels of Lactobacillus and Enterococcus (9.95 ± 0.89, 11.31 ± 1.05) in the study group were higher than those in the routine group (9.11 ± 0.74, 10.38 ± 0.94), and the levels of yeast-like fungi in the study group (3.08 ± 0.24) were lower than those of the routine group (3.82 ± 0.31) (P > 0.05). Conclusion: The standardized dietary avoidance therapy is remarkable in the treatment of CMPA, in which the children were able to tolerate ordinary milk earlier, and the intestinal flora was significantly improved, thereby promoting the growth and development of children. It therefore merits clinical promotion.

Effects of Amendments and Indigenous Microorganisms on the Growth and Cd and Pb Uptake of Coriander (Coriandrum sativum L.) in Heavy Metal-Contaminated Soils.

Heavy metal (HM) contamination of soils is a worldwide problem with adverse consequences to the environment and human health. For the safe production of vegetables in contaminated soil, efficient soil amendments need to be applied such as nano-hydroxyapatite (n-HAP) and poly γ-glutamic acid (γ-PGA), which can mitigate heavy metal uptake and enhance crop yield. However, the combined effects of soil amendments and indigenous microorganisms (IMOs) on HMs immobilisation and accumulation by crops have received little attention. We established a pot experiment to investigate the effects of IMOs combined with n-HAP and γ-PGA on coriander (Coriandrum sativum L.) growth and its Cd and Pb uptake in two acidic soils contaminated with HMs. The study demonstrated that applying n-HAP, with and without IMOs, significantly increased shoot dry biomass and reduced plant Cd and Pb uptake and diethylenetriaminepentaacetic acid (DTPA) extractable Cd and Pb concentrations in most cases. However, γ-PGA, with and without IMOs, only reduced soil DTPA-extractable Pb concentrations in slightly contaminated soil with 0.29 mg/kg Cd and 50.9 mg/kg Pb. Regardless of amendments, IMOs independently increased shoot dry biomass and soil DTPA-extractable Cd concentrations in moderately contaminated soil with 1.08 mg/kg Cd and 100.0 mg/kg Pb. A synergistic effect was observed with a combined IMOs and n-HAP treatment, where DTPA-extractable Cd and Pb concentrations decreased in slightly contaminated soil compared with the independent IMOs and n-HAP treatments. The combined treatment of γ-PGA and IMOs substantially increased shoot dry biomass in moderately contaminated soil. These results indicate that solo n-HAP enhanced plant growth and soil Cd and Pb immobilisation, and mitigated Cd and Pb accumulation in shoots. However, the combination of n-HAP and IMOs was optimal for stabilising and reducing HMs' uptake and promoting plant growth in contaminated soil, suggesting its potential for safe crop production.

New insight into amyloid fibril formation of hen egg white lysozyme using a two-step temperature-dependent FTIR approach.

Hen egg white lysozyme (HEWL) is widely used in the mechanistic study of amyloid fibril formation. Yet, the fibrillation mechanism of HEWL is not well understood. In particular, in situ structural evidence for the on-pathway oligomeric intermediate has never been captured. Such evidence is crucial for confirming nucleated conformational conversion mechanism. Herein, we attempt to use a two-step temperature-dependent Fourier transform infrared (FTIR) approach to capture the in situ evidence for the on-pathway oligomeric intermediate and the oligomer-to-fibril transition during HEWL fibrillation. Key features of this approach include using lower temperature to generate the on-pathway oligomeric intermediate, using elevated temperature to eliminate the interference from the off-pathway oligomer and to facilitate the oligomer-to-fibril transition, and using FTIR difference spectroscopy and atomic force microscopy to tackle structure and morphology. Using such an approach, we reveal that the on-pathway oligomeric intermediate is in parallel ß-sheet configuration featuring a frequency at 1622 cm(-1) and the oligomer-to-fibril transition is accompanied by a spectral transition from 1622 to 1618 cm(-1). We also discover the beneficial role of the off-pathway oligomer in the capturing of the transient on-pathway oligomeric intermediate by serving as a monomer-releasing reservoir. This approach should also be useful in other amyloidogenic systems.

Parallel ß-sheet fibril and antiparallel ß-sheet oligomer: new insights into amyloid formation of hen egg white lysozyme under heat and acidic condition from FTIR spectroscopy.

Hen egg white lysozyme (HEWL) is widely used as a model protein for amyloid research. In this study, we aim to use Fourier transform infrared (FTIR) spectroscopy to gain new structural insights into amyloid formation of HEWL under heat and acidic condition. We reveal that the fibril-forming solution of HEWL has the capability to form fibril and oligomer with distinct ß-sheet configurations under different temperatures. Amyloid fibril with parallel ß-sheet configuration is formed at elevated temperature, while oligomer with antiparallel ß-sheet configuration is formed at room temperature. The interplay between fibrillation and oligomerization suggests that the two ß-sheet aggregates consume the same amyloidogenic materials such as peptide fragments and nicked HEWL due to lysozyme hydrolysis under heat and acidic condition. Temperature-dependent FTIR reveals that the oligomer is unstable at elevated temperature, demonstrating its off-pathway nature. The temperature-dependent formation of parallel and antiparallel ß-sheet configurations discovered in lysozyme system is compared with that of amyloid-ß and α-synuclein systems and the implication is discussed.