Cholesterol Efflux-Independent Modification of Lipid Rafts by AIBP (Apolipoprotein A-I Binding Protein).

OBJECTIVE: AIBP (apolipoprotein A-I binding protein) is an effective and selective regulator of lipid rafts modulating many metabolic pathways originating from the rafts, including inflammation. The mechanism of action was suggested to involve stimulation by AIBP of cholesterol efflux, depleting rafts of cholesterol, which is essential for lipid raft integrity. Here we describe a different mechanism contributing to the regulation of lipid rafts by AIBP. Approach and Results: We demonstrate that modulation of rafts by AIBP may not exclusively depend on the rate of cholesterol efflux or presence of the key regulator of the efflux, ABCA1 (ATP-binding cassette transporter A-I). AIBP interacted with phosphatidylinositol 3-phosphate, which was associated with increased abundance and activation of Cdc42 and rearrangement of the actin cytoskeleton. Cytoskeleton rearrangement was accompanied with reduction of the abundance of lipid rafts, without significant changes in the lipid composition of the rafts. The interaction of AIBP with phosphatidylinositol 3-phosphate was blocked by AIBP substrate, NADPH (nicotinamide adenine dinucleotide phosphate), and both NADPH and silencing of Cdc42 interfered with the ability of AIBP to regulate lipid rafts and cholesterol efflux. CONCLUSIONS: Our findings indicate that an underlying mechanism of regulation of lipid rafts by AIBP involves PIP-dependent rearrangement of the cytoskeleton.

Release of nanoclay and surfactant from polymer-clay nanocomposites into a food simulant.

Release assessment of organo-modified montmorillonite (O-MMT) nanoclay and the organo-modifiers (surfactants) was performed on two types of polymer­clay nanocomposites: polypropylene (PP) and polyamide 6 (PA6) with O-MMT. In accordance with ASTM D4754-11, nanocomposite films were exposed to ethanol as a fatty-food simulant at 70 °C. The release of O-MMT, with Si and Al used as the nanoclay markers, was evaluated by graphite furnace atomic absorption spectrometry. The nanoclay particles released in ethanol were visualized by transmission electron microscopy (TEM). More nanoclay particles were released from PP­clay films (0.15 mg L(­1)) than from PA6­clay films (0.10 mg L(­1)), possibly due to the lack of interaction between the nanoclay and PP as indicated by the structure and morphology in the TEM images. The surfactant release was quantified by a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. A substantial amount of surfactant was released into ethanol (3.5 mg L(­1) from PP­clay films and 16.2 mg L(­1) from PA6­clay films), indicating changes in the nanoclay structure within the nanocomposite while it was exposed to ethanol. This research has provided information for the determination of exposure doses of nanoclay and surfactant in biosystems and the environment, which enabled the risk assessment.

Metabolomics analysis reveals enhanced salt tolerance in maize through exogenous Valine-Threonine-Isoleucine-Aspartic acid application.

Salt stress is a well-known abiotic constraint that hampers crop productivity, affecting more than 424 million hectares of topsoil worldwide. Applying plant growth regulators externally has proven effective in enhancing crop resilience to salt stress. Previous metabolomics studies revealed an accumulation of Valine-Threonine-Isoleucine-Aspartic acid (VTID) in salt-stressed maize seedlings, suggesting its potential to assist maize adaptation to salt stress. To explore the effectiveness of VTID in enhancing salt tolerance in maize, 10 nM VTID was applied to salt-stressed maize seedlings. The results showed a remarkable 152.29% increase in plant height and a 122.40% increase in fresh weight compared to salt-stressed seedlings. Moreover, the addition of VTID enhanced the activity of antioxidant enzymes, specifically superoxide dismutase (SOD) and catalase (CAT), while reducing the level of malondialdehyde (MDA), a marker of oxidative stress. Additionally, VTID supplementation resulted in a significant increase in osmoregulatory substances such as proline. Metabolomic analysis revealed substantial changes in the metabolite profile of maize seedlings when treated with VTID during salt stress. Differential metabolites (DMs) analysis revealed that the identified DMs primarily belonged to lipids and lipid-like molecules. The receiver operating characteristic curve and linear regression analysis determined a correlation between isodolichantoside and the height of maize seedlings under salt-stress conditions. In conclusion, these findings validate that VTID effectively regulates tolerance in maize seedlings and offers valuable insights into the potential of short peptides for mitigating salt stress.

Identification and analysis of the degradation products of chlorothalonil in vegetables.

In this study, the untargeted screening of the degradation products of chlorothalonil (CHT) in vegetables was performed using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS). Sulfhydryl-CHT (SH-CHT) and hydroxyl CHT (OH-CHT) were screened as the key degradation products of CHT in vegetables. SH-CHT is a new degradation product of CHT in the vegetables. This study was the first discover the SH-substituted degradation product of pesticide in vegetables. The chemical structure of SH-CHT was deduced and confirmed through synthetic reference. An efficient method for the simultaneous monitoring of SH-CHT and hydroxyl CHT (OH-CHT) in vegetables has been proposed based on QuEChERS in combination with HPLC-MS/MS analysis. The recoveries of SH-CHT and OH-CHT were in range of 85.8%-105.1% with intra- and inter-relative standard deviation (RSD) of less than 10.0%. The limits of detection were 2.0 µg/kg for SH-CHT and 0.2 µg/kg for OHCHT. Seven kinds of vegetables covering various plant families were processed with CHT. As a result, SH-CHT was detected in five kinds of sulfur-rich vegetables with transformation rates of 7.6%-26.6%. OH-CHT was detected in all the vegetables with transformation rates of 1.7%-14.0%. Toxicity evaluation based on ECOSAR program indicated that SH-CHT had potentially high toxicity to aquatic organisms. This study provides a powerful approach for the monitoring and risk assessment of SH-CHT and OH-CHT in food safety control. Furthermore, the study inspires comprehensive research on the overlooked degradation pathways of pesticides in sulfur-rich vegetables.

Relationship between tooth loss and sarcopenia in suburban community-dwelling older adults in Shanghai and Tianjin of China.

Both sarcopenia and loss of teeth are associated with aging. The purpose of this study was to investigate potential relationships between tooth loss and sarcopenia and its components in suburban community-dwelling older adults of Shanghai and Tianjin, China. The subjects were 1494 people over 60 years of age (40.7% men; aged 71.64 ± 5.97 years) from Chongming District of Shanghai and Hangu District of Tianjin. Asian Working Group for Sarcopenia(AWGS) criteria were used to define sarcopenia. Muscle mass, muscle strength, and physical performance were assessed using a bioelectrical impedance analyzer, a grip strength test, and a four-meter walk test, respectively. The subjects were divided into groups depending on self-reported loss of teeth. Our studies found no correlation between tooth loss and sarcopenia or muscle mass. However, the walking speed of female participants with at least 10 teeth lost was 0.059 m/s slower than that of participants with fewer than 10 teeth lost (p < 0.001), and grip strength was 1.577 kg lower among male participants with at least 10 teeth lost than among males with fewer than 10 teeth lost (p = 0.023). These results are consistent with the importance of good oral hygiene in preventing declines of physical performance in older adults.

Effect of ionising irradiation on silver release from polyolefin/silver nanocomposite films into food simulants.

Two types of nanocomposite films, polyethylene/silver (PE/Ag) and polypropylene/silver (PP/Ag), were prepared and characterised. Assessment of silver released under the effect of ionising irradiation was performed on the nanocomposite films. The release experiment was carried out by immersing the nanocomposite films in water, 3% acetic acid or 95% ethanol as food simulants and measuring the Ag release from nanocomposite films treated with and without gamma or electron beam irradiation at a dose of 10 kGy. In general, irradiation treatment increased the Ag release regardless of the type of polymer and food simulant. One reason could be radiation-induced metal oxidation at the surface which in turn promoted ion release into food simulants. The oxidising radicals produced by radiation in solution could be another factor speeding up metal oxidation and subsequent ion release. When comparisons were made between the two types of irradiation, greater Ag release into water and 3% acetic acid was observed after electron beam irradiation, while gamma irradiation was likely to induce greater Ag release into 95% ethanol. Such phenomena reveal the influence of different types of radiation on the solutions which in turn affect the Ag release.

Normalization of cholesterol metabolism in spinal microglia alleviates neuropathic pain.

Neuroinflammation is a major component in the transition to and perpetuation of neuropathic pain states. Spinal neuroinflammation involves activation of TLR4, localized to enlarged, cholesterol-enriched lipid rafts, designated here as inflammarafts. Conditional deletion of cholesterol transporters ABCA1 and ABCG1 in microglia, leading to inflammaraft formation, induced tactile allodynia in naive mice. The apoA-I binding protein (AIBP) facilitated cholesterol depletion from inflammarafts and reversed neuropathic pain in a model of chemotherapy-induced peripheral neuropathy (CIPN) in wild-type mice, but AIBP failed to reverse allodynia in mice with ABCA1/ABCG1-deficient microglia, suggesting a cholesterol-dependent mechanism. An AIBP mutant lacking the TLR4-binding domain did not bind microglia or reverse CIPN allodynia. The long-lasting therapeutic effect of a single AIBP dose in CIPN was associated with anti-inflammatory and cholesterol metabolism reprogramming and reduced accumulation of lipid droplets in microglia. These results suggest a cholesterol-driven mechanism of regulation of neuropathic pain by controlling the TLR4 inflammarafts and gene expression program in microglia and blocking the perpetuation of neuroinflammation.

Identification of chemicals in a polyvinyl chloride/polyethylene multilayer film by ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and their migration into solution.

An ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) method was employed for chemical identification in a commercial polyvinyl chloride/polyethylene (PVC/PE) multilayer film. Over 30 chemicals from different layers (PE layer, PVC layer, and adhesive layer) of the film were identified and were classified into 6 groups, including antioxidants, plasticizers, slip agents, antistatic agents, adhesive components, etc. Special attention was placed on the analysis of some non-intentionally added substances and oligomers in adhesive. Based on the identification results, six additives (all from PE layer) were selected and their migration behaviors were investigated via one-sided contact migration test. The migration test was performed by exposing the PE side of the film to different simulating solutions (water, 40% ethanol, and 95% ethanol) at 40°C, as well as recording the migration level as a function of time. No obvious migration was found into water for all additives, while the migration into 40% and 95% ethanol followed Fickian diffusion behavior, and could be described by Fick's diffusion equation. Diffusion coefficients derived from the equation were in a range of 10-13 to 10-10 cm2/s and were dependent on the type of additive and solution.

AIBP protects retinal ganglion cells against neuroinflammation and mitochondrial dysfunction in glaucomatous neurodegeneration.

Glaucoma is a leading cause of blindness worldwide in individuals 60 years of age and older. Despite its high prevalence, the factors contributing to glaucoma progression are currently not well characterized. Glia-driven neuroinflammation and mitochondrial dysfunction play critical roles in glaucomatous neurodegeneration. Here, we demonstrated that elevated intraocular pressure (IOP) significantly decreased apolipoprotein A-I binding protein (AIBP; gene name Apoa1bp) in retinal ganglion cells (RGCs), but resulted in upregulation of TLR4 and IL-1ß expression in Müller glia endfeet. Apoa1bp-/- mice had impaired visual function and Müller glia characterized by upregulated TLR4 activity, impaired mitochondrial network and function, increased oxidative stress and induced inflammatory responses. We also found that AIBP deficiency compromised mitochondrial network and function in RGCs and exacerbated RGC vulnerability to elevated IOP. Administration of recombinant AIBP prevented RGC death and inhibited inflammatory responses and cytokine production in Müller glia in vivo. These findings indicate that AIBP protects RGCs against glia-driven neuroinflammation and mitochondrial dysfunction in glaucomatous neurodegeneration and suggest that recombinant AIBP may be a potential therapeutic agent for glaucoma.

Interaction of nanoclay-reinforced packaging nanocomposites with food simulants and compost environments.

The production of engineered nanomaterials (ENMs) has increased exponentially over the last few decades. ENMs, made from use of engineered nanoparticles (ENPs), have been applied to the food, agriculture, pharmaceutical, and automobile industries. Of particular interest are their applications in packaging nanocomposites for consumer and non-consumer goods. ENPs in nanocomposites are of interest as a packaging material because they reduce the amount of polymer needed, while improving the physical properties. However, the transformation of ENPs in nanocomposite production, their fate, and their toxicity remain unknown while in contact with the package content or after the end of life. The objectives of this chapter are (a) to provide an overview of the main nanoclays used in packaging; (b) to categorize the main polymeric packaging nanocomposites; (c) to provide an overview of the fate and mass transport of ENPs, especially nanoclays; (d) to describe the mass transfer of nanoclays in food simulants and in compost environments; and (e) to identify current and future research needs.

Carbon quantum dots embedded mesoporous silica for rapid fluorescent detection of acidic gas.

A fluorescent composite consisting of an ordered mesoporous material (MCM-41) and carbon quantum dots (CQDs) was successfully prepared and designated as MCM/CQDs. CQDs with citric acid as a carbon source and diethylenetriamine as a nitrogen doping agent were directly synthesized in MCM-41 via a hydrothermal method and the reaction conditions were optimized. The MCM/CQDs prepared at the optimized condition showed different fluorescent properties (as indicated by the fluorescent emission wavelength and fluorescent response to acid) compared to the CQDs formed in water. It was found that the preparation of MCM/CQDs caused changes in the characteristics (i.e., surface and pore properties) of MCM-41, which in turn could impact the formation of CQDs in MCM-41. The prepared MCM/CQDs combined the porous nature of MCM-41 and the fluorescent properties of CQDs, and can be applied to the rapid detection of acetic acid (HAc) as a model organic volatile compound. The detection was more sensitive for HAc gas (detection limit: 0.2 µmol/L) than for HAc solution (detection limit: 3 µmol/L). The reason was explained by the physical adsorption of HAc gas by MCM-41, which increased the HAc concentration in the MCM/CQDs and therefore enhanced the fluorescent response. This study expanded the potential application of CQDs embedded mesoporous silica in gas sensing, especially in the rapid and sensitive detection of acetic acid as a representative of acidic volatile compounds.

Preparation and performance of a BTDA-modified polyurea microcapsule for encapsulating avermectin.

A pesticide microcapsule was prepared by encapsulating avermectin (AVM) in a polyurea microcapsule via interfacial polymerization in acetic ether/water emulsion. The polyurea microcapsule was consisted of chitosan oligomer (CO) as the membrane material and diphenyl methane-4,4'-diisocyanate (MDI) as the crosslinker. A chemical modification was carried out by grafting a UV-absorbent, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), to CO before interfacial polymerization to enhance the UV-resistance of the microcapsule. The BTDA grafted CO (CO-BTDA) and the AVM microcapsules were characterized by a variety of instrumental techniques, including NMR, FTIR, UV-vis, GPC-LS, DLS, SEM and TEM. The in vitro release test showed that the polyurea microcapsule maintained the sustained release of AVM for a longer period (up to 120 h) in comparison with the commercial AVM formulations (within 24 h). The photodegradation test revealed that the polyurea microcapsule significantly reduced the AVM degradation and extended the half-life of AVM from 4.16 h to 9.43 h. The AVM degradation was further reduced by using the BTDA-modified polyurea microcapsule. The corresponding half-life was extended up to 17.33 h and can be mediated by changing the mass ratio of BTDA: CO during the synthesis of CO-BTDA. The use of polyurea microcapsule did not raise a concern about pesticide residue as no AVM was detected after the photodegradation test. In addition, the polyurea microcapsule itself was subject to degradation under sunlight exposure, which reduced its residue in the environment.

Carbon nanotube release from polymers into a food simulant.

The release assessment of multi-walled carbon nanotubes (CNTs) was performed on two types of polymer-CNT nanocomposites: polypropylene (PP) and polyamide 6 (PA6) containing 3 wt% CNT. Nanocomposite films were prepared and then exposed to ethanol as a fatty-food simulant at 40 °C, and the amount of CNT release into ethanol was determined by ultraviolet-visible spectroscopy (UV-Vis) and graphite furnace atomic absorption spectrometry (GFAAS). The CNTs released into ethanol were visualized by transmission electron microscopy (TEM) and verified by Raman spectroscopy. UV-Vis analysis showed a very small amount of CNT release from the nanocomposite films into ethanol over 60 d: maximum CNT concentrations in ethanol were 1.3 mg/L for the PP-CNT film and 1.2 mg/L for the PA6-CNT film. GFAAS results indicated that the amount of CNTs released into ethanol after 12 d was over 20-fold higher than the results obtained by UV-Vis. Overestimation of CNT release by GFAAS suggested aggregation and poor dispersion of CNTs in the solvent. This assumption was verified by TEM images exhibiting the embedded CNTs in the polymer flakes, which could be poorly dispersed in the solvent. In general, CNT release from the nanocomposite films was considered a surface phenomenon, as indicated by detachment of CNT-containing polymer flakes from the film surface.

A Turn-On Fluorescent Sensor for Selective and Sensitive Detection of Alkaline Phosphatase Activity with Gold Nanoclusters Based on Inner Filter Effect.

In this work, a novel approach for simple and sensitive determination of alkaline phosphatase (ALP) is developed on the basis of an inner filter effect of p-nitrophenylphosphate (PNPP) on the fluorescence of gold nanoclusters (AuNCs). AuNCs with a high quantum yield of 12% were synthesized by one-pot strategy and were directly applied as fluorescent substance. When AuNCs were mixed with PNPP, the fluorescence of the AuNCs was remarkably quenched or was decreased via the inner filter effect since the absorption spectrum of PNPP overlaps well with the excitation spectrum of the AuNCs. While in the presence of ALP, PNPP was catalytically hydrolyzed into p-nitrophenol, which has different absorption characteristics from those of PNPP, resulting in the recovery of the AuNCs fluorescence. Thus, a novel "turn-on" fluorescent sensor for detecting ALP was established with a detection limit as low as 0.002 U/L (signal-to-noise ratio of 3). The turn-on fluorescent sensor exhibits many merits such as high sensitivity, excellent selectivity, and high signal output because of the low background signals. In addition, the developed sensing method was successfully applied to investigate ALP inhibitors and ALP determination in serum samples. A good linear relationship was obtained in the range from 0.02 to 50 U/L, and satisfactory recoveries at four spiking levels of ALP ranged from 95% to 106% with precision below 5%. The very simple sensing approach proposed here should promote the development of fluorescence turn-on chemosensors for chemo/biodetection.

Novel Active Surface Prepared by Embedded Functionalized Clays in an Acrylate Coating.

The research on a self-decontaminating surface has received significant attention because of the growth of pathogenic microorganisms on surfaces. In this study, a novel and simple technique for producing an active surface with antimicrobial functionality is demonstrated. A tethering platform was developed by grafting the biocide ampicillin (Amp) to a nanoclay and dispersing the nanoclay in a UV-curable acrylate coating applied on polypropylene films as the substrate. A coupling agent, [3-(glycidyloxy)propyl]trimethoxysilane, was used as a linker between the nanoclay and Amp. The Amp-functionalized clay was further modified with an organic surfactant to improve the compatibility with the coating. Several characterization assays, such as Fourier infrared transform analysis, thermogravimetric analysis, and X-ray diffraction, were conducted to confirm the presence of Amp in the nanoclay. Transmission electron microscopy images revealed that the clay particles were well dispersed in the coating and had a partial exfoliated morphology. The active coating surface was effective in inhibiting the growth of Gram-positive Listeria monocytogenes and Gram-negative Salmonella Typhimurium via contact. These findings suggest the potential for the development of active surfaces with the implementation of nanotechnology to achieve diverse functionalities.

Fluorescent labeling and tracking of nanoclay.

We report a methodology developed to detect and track stable fluorescent-labeled nanoclay, in polymer-clay nanocomposite films, and in a contact solvent after migration testing. Fluorescein-5-maleimide (fluorescein) or tetramethylrhodamine-5-maleimide (rhodamine) was covalently bonded to organically modified montmorillonite (o-MMT). Fluorescein- and rhodamine-labeled nanoclay showed good thermal stability up to 220 °C and the rhodamine-labeled nanoclay remained stable at 250 °C. Confocal laser scanning microscopy was used to confirm the tagging and to detect the fluorescent-labeled nanoclays in various systems.