Microglia-dependent excessive synaptic pruning leads to cortical underconnectivity and behavioral abnormality following chronic social defeat stress in mice.

Synapse loss in medial prefrontal cortex (mPFC) has been implicated in stress-related mood disorders, such as depression. However, the exact effect of synapse elimination in the depression and how it is triggered are largely unknown. Through repeated longitudinal imaging of mPFC in the living brain, we found both presynaptic and postsynaptic components were declined, together with the impairment of synapse remodeling and cross-synaptic signal transmission in the mPFC during chronic stress. Meanwhile, chronic stress also induced excessive microglia phagocytosis, leading to engulfment of excitatory synapses. Further investigation revealed that the elevated complement C3 during the stress acted as the tag of synapses to be eliminated by microglia. Besides, chronic stress induced a reduction of the connectivity between the mPFC and neighbor regions. C3 knockout mice displayed significant reduction of synaptic pruning and alleviation of disrupted functional connectivity in mPFC, resulting in more resilience to chronic stress. These results indicate that complement-mediated excessive microglia phagocytosis in adulthood induces synaptic dysfunction and cortical hypo-connectivity, leading to stress-related behavioral abnormality.

Polarization conversion metasurface design based on characteristic mode rotation and its application into wideband and miniature antennas with a low radar cross section.

In this paper, a characteristic mode rotation (CMR) method has been proposed to design a compact metasurface antenna with a low radar cross section (RCS) in a wideband. In the proposed CMR method, the incident wave dependent complex characteristic currents corresponding to the dominant characteristic modes solved by the characteristic mode method (CMM) are calculated. With the direction of the superposition of the complex characteristic currents orthogonal to that of the incident electric field in the CMR method, the metasurface subarray with wideband polarization conversion characteristic is designed. By arranging the metasurface subarray in a rotation way, a metasurface array with a compact size of 1.28λ0×1.28λ0 is designed for wideband RCS reduction. A miniature circle patch antenna is integrated with the metasurface array to achieve not only good radiation performance but also low observability for the in-band and the out-of-band of the antenna. Simulated and measured results demonstrate that the proposed miniature metasurface antenna designed by the CMR method has a good broadside radiation pattern, a maximal gain of 10.75 dB, and a -10 dB RCS reduction characteristic in the wide band of 6∼20.7 GHz with a fractional band of 110%.

Prolongation of the degradation period and improvement of the angiogenesis of zein porous scaffolds in vivo.

Zein porous scaffolds modified with fatty acids have shown great improvement in mechanical properties and good cell compatibility in vitro, indicating the potential application as a bone tissue engineering substitute. The present study was conducted to systematically investigate whether the addition of fatty acids affects the short-term (up to 12 weeks) and long-term (up to 1 year) behaviors of scaffolds in vivo, mainly focusing on changes in the degradation period and inflammatory responses. Throughout the implantation period, no abnormal signs occurred and zein porous scaffolds modified with oleic acid showed good tolerance in rabbits, characterized by the growth of relatively more blood vessels in the scaffolds and only a slight degree of fibrosis histology. Moreover, the degradation period was prolonged from 8 months to 1 year as compared to the control. These results affirmed further that zein could be used as a new kind of natural biomaterial suitable for bone tissue engineering.

Antineoplastic Activity Comparison of Bovine Serum Albumin--Conjugated Sulfides Semiconductor Nanomaterials.

Although tumor is one of the most frequently occurring diseases and a leading cause of death, nanotechnology, one of the frontier sciences, is exhibiting its great potential to tumor treatments. The aim of this study was to design a facile and environmentally-friendly method to prepare bovine serum albumin-conjugated heavy metal sulfides nano-materials, including Ag2S, PbS and CdS. Here, bovine serum albumin was introduced in order to direct the synthesis of nano-materials by using its template effect and supply more sites for further modification in future. The crystal structure and morphology were analyzed by XRD and TEM, respectively. Additionally, the antineoplastic activity of nano-materials was compared by cell viability analysis, optical and electron microscopy observation after exposure of the human hepatoma cell line. The results showed that the inhibition effect of heavy metal sulfides on tumor cells was in the order of nano-PbS > bulk CdS > nano-Ag2S > nano-CdS > bulk PbS > bulk Ag2S. It could be concluded that heavy metal sulfides had significantly negative impact on human hepatoma cells growth but it could not be obviously generalized that nano-particles were always more effective to kill tumor cells than bulk materials. The size and surface reactivity might be the important factors causing the difference.

Melatonin Ameliorates Depressive-Like Behaviors in Ovariectomized Mice by Improving Tryptophan Metabolism via Inhibition of Gut Microbe Alistipes Inops.

Melatonin (N-acetyl-5-methoxytryptamine) is reported to improve mood disorders in perimenopausal women and gut microbiome composition is altered during menopausal period. The possible role of microbiome in the treatment effect of melatonin on menopausal depression remains unknown. Here, it is shown that melatonin treatment reverses the gut microbiota dysbiosis and depressive-like behaviors in ovariectomy (OVX) operated mice. This effect of melatonin is prevented by antibiotic cocktails (ABX) treatment. Transferring microbiota harvested from adolescent female mice to OVX-operated mice is sufficient to ameliorate depressive-like behaviors. Conversely, microbiota transplantation from OVX-operated mice or melatonin-treated OVX-operated mice to naïve recipient mice exhibits similar phenotypes to donors. The colonization of Alistipes Inops, which is abundant in OVX-operated mice, confers the recipient with depressive-like behaviors. Further investigation indicates that the expansion of Alistipes Inops induced by OVX leads to the degradation of intestinal tryptophan, which destroys systemic tryptophan availability. Melatonin supplementation restores systemic tryptophan metabolic disorders by suppressing the growth of Alistipes Inops, which ameliorates depressive-like behaviors. These results highlight the previously unrecognized role of Alistipes Inops in the modulation of OVX-induced behavioral disorders and suggest that the application of melatonin to inhibit Alistipes Inops may serve as a potential strategy for preventing menopausal depressive symptoms.

Gut microbiome-derived ammonia modulates stress vulnerability in the host.

Ammonia has been long recognized as a metabolic waste product with well-known neurotoxic effects. However, little is known about the beneficial function of endogenous ammonia. Here, we show that gut ammonia links microbe nitrogen metabolism to host stress vulnerability by maintaining brain glutamine availability in male mice. Chronic stress decreases blood ammonia levels by altering gut urease-positive microbiota. A representative urease-producing strain, Streptococcus thermophilus, can reverse depression-like behaviours induced by gut microbiota that was altered by stress, whereas pharmacological inhibition of gut ammonia production increases stress vulnerability. Notably, abnormally low blood ammonia levels limit the brain's availability of glutamine, a key metabolite produced by astrocytes that is required for presynaptic γ-aminobutyric acid (GABA) replenishment and confers stress vulnerability through cortical GABAergic dysfunction. Of therapeutic interest, ammonium chloride (NH4Cl), a commonly used expectorant in the clinic, can rescue behavioural abnormalities and GABAergic deficits in mouse models of depression. In sum, ammonia produced by the gut microbiome can help buffer stress in the host, providing a gut-brain signalling basis for emotional behaviour.

Water-responsive 4D printing based on self-assembly of hydrophobic protein "Zein" for the control of degradation rate and drug release.

Four-dimensional (4D) printing is a promising technology that provides solutions for compelling needs in various fields. Most of the reported 4D printed systems are based on the temporal shape transformation of printed subjects. Induction of temporal heterogenicity in functions in addition to shape may extend the scope of 4D printing. Herein, we report a 4D printing approach using plant protein (zein) gel inspired by the amyloid fibrils formation mechanism. The printing of zein gel in a specialized layered-Carbopol supporting bath with different water concentrations in an ethanol-water mixture modulates hydrophobic and hydrogen bonding that causes temporal changes in functions. The part of the construct printed in a supporting bath with higher water content exhibits higher drug loading, faster drug release and degradation than those printed in the supporting bath with lower water content. Tri-segment conduit and butterfly-shaped construct with two asymmetrical wings are printed using this system to evaluate biomedical function as nerve conduit and drug delivery system. 4D printed conduits are also effective as a drug-eluting urethral stent in the porcine model. Overall, this study extends the concept of 4D printing beyond shape transformation and presents an approach of fabricating specialized baths for 4D printing that can also be extended to other materials to obtain 4D printed medical devices with translational potential.

Injectable zein gel with in situ self-assembly as hemostatic material.

Zein is a biocompatible and biodegradable corn protein with promising properties for biomedical applications. It is hydrophobic with the ability to self-assemble in an aqueous medium. It can also form a gel in hydroalcoholic solvents at higher concentrations. Few studies have investigated the biomedical significance of zein gels. Herein, we exploited the injectability and water-responsive increase in stiffness of zein gel to achieve hemostasis by physical blockage of the wound and clot formation. The release of components from the gel further aided blood clotting and gave a higher clot strength than a natural clot, which can prevent rebleeding. Rabbit aortic injury and swine femoral artery injury models were used to evaluate the hemostatic efficacy of the zein gel. Zein gel was effective in both hemostatic models without applying external compression due to an in situ increase in stiffness, while the control (Celox™ Gauze) required external compression at the wound site. The zein gel was easily removed after hemostasis due to hydrophobic self-assembly. Overall, zein gel is proposed as an effective hemostatic product for any wound shape owing to its good shape adaptability and rapid in situ blood-responsive stiffness increase.

Zein nanospheres assisting inorganic and organic drug combination to overcome stent implantation-induced thrombosis and infection.

The complication of stent implantation is the biggest obstacle to the success of its clinical application. In this study, we developed a combination way of 3D printing and the coating technique for preparation of functional polyurethane stents against stent implantation-induced thrombosis and postoperative infection. SEM, XPS, static water contact angle, and XRD demonstrated that the functional polyurethane stent had a 37 µm-thickness membrane composed of zein nanospheres (250-350 nm). Meanwhile, ZnO nanoparticles were encapsulated in zein nanospheres while heparin was adsorbed on the surface, causing 97.1 ± 6.4 % release of heparin in 120 min (first-order kinetic model) and 62.7 ± 5.6 % release of Zn2+ in 9 days (Korsmeyer-Peppas model). The mechanical analysis revealed that the functional polyurethane stents had about 8.61 MPa and 2.5 MPa tensile strength and bending strength, respectively. The in vitro biological analysis showed that the functional polyurethane stents had good EA.hy926 cells compatibility (97.9 ± 3.8 %), anti-coagulation response (comparable plasma protein, platelet adhesion and suppressed clotting) and sustained antibacterial activities by comparison with the bare polyurethane stent. The preliminary evaluation by rabbit ex vivo carotid artery intervention experiment demonstrated that the functional polyurethane stents could maintain blood circulation under the continuous stresses of blood flow. Meanwhile, the detailed data from the simulated implant infection experiment in vivo showed the functional polyurethane stents could effectively reduce microbial infection by 3-6 times lower and improve fibrosis and macrophage infiltration.

Preparation and evaluation of chitosan/polyvinylpyrrolidone/zein composite hemostatic sponges.

Trauma-related excessive bleeding is one of the leading causes of death. Chitosan (CS) sponges have unique advantages in the treatment of massive bleeding, but their application is limited by poor stability and toxic crosslinking agent. In this work, chitosan/polyvinylpyrrolidone/zein (CS/PVP/Zein) sponges with macroporous structure were prepared, which exhibited rapid water absorption capacity and water-triggered expanding property with low cytotoxicity and low hemolysis ratio. In vitro blood coagulation experiments showed that CS/PVP/Zein sponges could clot blood significantly faster than commercial surgical gauze. Further investigation of the hemostatic mechanism suggested that the CS/PVP/Zein sponges could accelerate coagulation by promoting attachment of erythrocytes, activation of platelets, and rapid plasma protein absorption. Prepared sponges were also found effective in the rat femoral artery transection model to control bleeding. Overall, the CS/PVP/Zein sponges exhibited the potential to control trauma-related hemorrhage.

Long noncoding RNA Gm2694 drives depressive-like behaviors in male mice by interacting with GRP78 to disrupt endoplasmic reticulum homeostasis.

Long noncoding RNAs (lncRNAs) are involved in various biological processes and implicated in the regulation of neuronal activity, but the potential role of lncRNAs in depression remains largely unknown. Here, we identified that lncRNA Gm2694 was increased in the medial prefrontal cortex (mPFC) of male mice subjected to chronic social defeat stress (CSDS). The down-regulation of Gm2694 in the mPFC alleviated CSDS-induced depressive-like behaviors through enhanced excitatory synaptic transmission. Furthermore, we found that Gm2694 preferentially interacted with the carboxyl-terminal domain of 78-kilodalton glucose-regulated protein (GRP78), which abrogated GRP78 function and disrupted endoplasmic reticulum homeostasis, resulting in a reduction of the surface expression of AMPA receptors (AMPARs). Overexpression of GRP78 in the mPFC promoted the surface expression of AMPARs and attenuated the CSDS-induced depressive-like behaviors of mice. Together, our results unraveled a previously unknown role of Gm2694 in regulating endoplasmic reticulum homeostasis and excitatory synaptic transmission in depression.

Preparation of stretchable composite film and its application in skin burn repair.

The poor elasticity of wound dressings often leads to wound healing failure due to rupture and fall off. In this study, the composite films of zein and hydrogel poly (acrylic acid) were developed in order to obtain stretchable wound dressing for skin burn repair. The mechanical test revealed that the maximum elongation of break of composite films could reach 349.76% when the mass ratio of zein to poly (acrylic acid) was 1.5. SEM and FTIR analysis demonstrated the good elasticity of composite films might be due to the formation of a dense structure and the strong interaction between zein and poly (acrylic acid). Interestingly, the composite films exhibited great adhesiveness to human finger skin and stretchable ability under strenuous joint exercise. CCK-8 assay and fluorescence staining showed that the composite films and their extract had good cytocompatibility on human foreskin fibroblasts (L929) cells. The in vivo experiment on rat's skin burning model indicated that the composite films could promote wound healing and collagen synthesis by comparison with commercial gauze. It could be concluded that the stretchable composite films of zein and hydrogel poly (acrylic acid) had the potential as the wound dressing.

Toxicity of CuS/CdS semiconductor nanocomposites to liver cells and mice liver.

Semiconductor nanomaterials not only bring great convenience to peoples lives but also become a potential hazard to human health. The purpose of this study was to evaluate the toxicity of CuS/CdS nanocomposites in hepatocytes and mice liver. The CuS/CdS semiconductor nanocomposites were synthesized by a biomimetic synthesis - ion exchange strategy. Nanosize was confirmed by high-resolution transmission electron microscopy and dynamic light scattering. The composition and physical properties were measured by powder X-ray diffraction, Fourier transform infrared spectra, atomic absorption spectroscopy, thermogravimetry-differential scanning calorimetry and zeta potential analysis. The results revealed that CuS/CdS nanocomposites had 8.7 nm diameter and negative potential. Ion exchange time could adjust the ratio of CuS and CdS in nanocomposites. The toxicological study revealed that CuS/CdS nanocomposites could be internalized into liver cells, inhibited endogenous defense system (e.g. GSH and SOD), induced the accumulation of oxidation products (e.g. ROS, GSSG and MDA), and caused hepatocyte apoptosis. The in vivo experiments in Balb/c mice showed that the experimental dose (4 mg/kg) didn't cause observable changes in mice behavior, physical activity and pathological characteristics, but the continuous accumulation of Cd2+ in the liver and kidney might be responsible for its long-term toxicity.

Preparation and evaluation of captopril loaded gastro-retentive zein based porous floating tablets.

In this study, gastro-retentive porous floating tablets of captopril based on zein are reported using l-menthol as a porogen. Tablets were prepared by the direct compression method. Removing of l-menthol through sublimation process generated pores in tablets, which decreased the density to promote floating over gastric fluid. Prepared tablets showed no floating lag time and prolong total floating time (>24 h). Drug release was found dependent upon porosity of tablets, an increase in porosity of tablets resulted in increased drug release, so it can be tuned by varying concentration of l-menthol. In addition to floating and sustained release properties, porous tablets showed robust mechanical behavior in wet conditions, which can enable them to withstand real gastric environment stress. In vivo studies using New Zealand rabbits also confirmed the prolonged gastric retention (24 h) and plasma drug concentration-time profile showed sustained release of captopril with higher Tmax and MRT as compared to marketed immediate-release tablets. Overall, it was concluded that effective gastric retention can be achieved using porous zein tablets using l-menthol as a porogen.

Preparation of ciprofloxacin loaded zein conduits with good mechanical properties and antibacterial activity.

Conduit scaffolds have potential applications in tissue engineering as nerve conduits, urological stent and blood vessel graft. Zein is a well-reported biopolymer in tissue engineering and drug delivery systems. Herein, we prepared ciprofloxacin loaded zein conduits using a facile rolling method. Zein conduits (ZCs) were evaluated for physical structure, porosity, bending stiffness, degradation, drug release, in vitro and in vivo antibacterial efficacy and cells toxicity. ZCs showed porous structure with porosity > 60 % and good mechanical strength with bending stiffness of 28.54 N.mm2. Slow enzymatic degradation (87 % in 30 days) was also observed for ZCs. Slow release of ciprofloxacin up to 42 days was observed that could assure prevention of post-implantation infection. In vitro and in vivo antibacterial study verified the short-time and long-time antibacterial efficacy of zein conduits on Gram-positive and Gram-negative bacteria. Live/dead measurement and CCK-8 assay on L929 cells demonstrated good cell compatibility for all zein conduits (>90 % cell viability and cells proliferation in 3 days). Overall, the rolling method could be exploited for preparation of ciprofloxacin loaded zein conduits, which had the potential for tissue engineering applications.

Comprehensive investigation of the relationship between organic content and waste activated sludge dewaterability.

The relationship between sludge organic fraction and its dewaterability is well known in practice. However, the formal study to reveal the underlying reason is limited. To improve understanding of the nature of organic content on sludge dewatering process, this study systematically evaluated the effects of sludge organic content on its dewaterability and revealed the underlying mechanism. Analysis of 10 waste activated sludge (WAS) samples with varying organic contents showed that capillary suction time (CST) increased linearly from 34.90 ± 0.10 s to 104.90 ± 0.30 s (R2 = 0.92, p < 0.01), whereas the solid content of centrifuge cake decreased from 21.23 %±0.45 % to 12.52 %±0.14 % (R2 = 0.89, p < 0.01) when organic fractionincreased from 35.72 % to 61.11 %. These results first confirmed that WAS dewatering performance was negatively correlated to its organic content. Then, the underlying mechanism was revealed by studying the basic physicochemical properties of WAS with various organic content. The results showed that sludge with a higher organic content generally had greater extracellular polymeric substances (EPS) content, lower density and higher negative zeta potential, which hinder the aggregation and flocculation of floc particles. These properties endow the WAS with a higher organic content generally possessed more bound water content, small pores, poorer fluidity, and stronger network strength. These characteristics can hamper the separation of water from sludge cake during dewatering. Based on which, this study discussed the potential of organic fraction as a surrogate of EPS for evaluating WAS dewaterability and indicated the organic fraction can be a useful and strong indicator of WAS dewaterability.

Enhancement of mechanical strength of TCP-alginate based bioprinted constructs.

To overcome the mechanical drawback of bioink, we proposed a supporter model to enhance the mechanical strength of bioprinted 3D constructs, in which a unit-assembly idea was involved. Based on Computed Tomography images of critical-sized rabbit bone defect, the 3D re-construction was accomplished by a sequenced process using Mimics 17.0, BioCAM and BioCAD software. 3D constructs were bioprinted using polycaprolactone (PCL) ink for the outer supporter under extrusion mode, and cell-laden tricalcium phosphate (TCP)/alginate bioink for the inner filler under air pressure dispensing mode. The relationship of viscosity of bioinks, 3D bioprinting pressure, TCP/alginate ratio and cell survival were investigated by the shear viscosities analysis, live/dead cell test and cell-counting kit 8 measurement. The viscosity of bioinks at 1.0 s-1-shear rate could be adjusted within the range of 1.75 ±â€¯0.29 Pa·s to 155.65 ±â€¯10.86 Pa·s by changing alginate concentration, corresponding to 10 kPa-130 kPa of printing pressure. This design with PCL supporter could significantly enhance the compressive strength and compressive modulus of standardized 3D mechanical testing specimens up to 2.15 ±â€¯0.14 MPa to 2.58 ±â€¯0.09 MPa, and 42.83 ±â€¯4.75 MPa to 53.12 ±â€¯1.19 MPa, respectively. Cells could maintain the high viability (over 80%) under the given printing pressure but cell viability declined with the increase of TCP content. Cell survival after experiencing 7 days of cell culture could be achieved when the ratio of TCP/alginate was 1 : 4. All data supported the feasibility of the supporter and unit-assembly model to enhance mechanical properties of bioprinted 3D constructs.

Anaerobic reductive bio-dissolution of jarosites by Acidithiobacillus ferrooxidans using hydrogen as electron donor.

Jarosites are secondary iron-hydroxyl-sulfate minerals and widely occur in bioleaching, acid mine drainage, and acid sulfate soil environments. Anaerobic reductive dissolution of jarosites is yet to be methodically examined. In this study, we explored the bio-dissolution of jarosites by Acidithiobacillus ferrooxidans (At. ferrooxidans) by using hydrogen in batch experiments. After bio-dissolution by At. ferrooxidans for 22 d, ferrous ion concentrations reached 10.07 mM (biologically produced jarosites), 7.68 mM (potassium jarosite), and 1.45 mM (lead jarosite). Strengthening the dissolved jarosites by decreasing the initial pH (pH < 2.0) or by adding citric acid (1, 5, and 10 mM) was inefficient for bio-dissolution owing to restricted cellular activity. The pathways of bio-dissolution should include direct contact bio-dissolution and indirect bio-dissolution and relate to the solubility of jarosites in a bio-dissolution system. The results demonstrate that anaerobic reductive bio-dissolution of jarosites by At. ferrooxidans using hydrogen shows potential. This study also provides opportunities to contribute to the development of the bioleaching field via the aerobic/anaerobic cycle using a single strain to control and reuse jarosites in situ.

Different DHA or EPA production responses to nutrient stress in the marine microalga Tisochrysis lutea and the freshwater microalga Monodus subterraneus.

This study investigated the effect of nitrogen (N) and phosphorous (P) stress on the production of DHA or EPA and total fatty acids (TFAs) in the marine microalga Tisochrysis lutea and the freshwater microalga Monodus subterraneus. Five N or P starvation/limitation conditions (N sufficient and P limited, N sufficient and P starved, N starved and P sufficient, N starved and P limited, and N and P starved) and one N and P sufficient condition (control) were studied. The results demonstrated that the proportion of DHA or EPA among TFAs and production in the microalgae suspensions decreased (57%, 73% for N stress and 18%, 51% for P stress, respectively) under N or P stress in both microalgae compared with the N and P sufficient group. Differently, DHA dry weight content of T. lutea decreased significantly, and EPA dry weight content of M. subterraneus decreased slightly under N starved conditions. Clear differences in TFA content/production and the relationship between TFA and DHA or EPA production/content and CO2 fixation were observed between the two microalgae. These results give a new sight on the difference between marine microalgae and freshwater microalgae. Meanwhile, it gave a potential application to produce DHA or EPA and TFA combining with CO2 fixation by these microalgae.

Formation of high-molecular-weight protein adducts by methyl docosahexaenoate peroxidation products.

In the present study, the formation of modified proteins by methyl docosahexaenoate (DHA) peroxidation products in the presence of a metal-catalyzed oxidation system was investigated. Metal-catalyzed oxidation of mixtures containing bovine serum albumin (BSA) and DHA led to formation of two high molecular weight derivatives of BSA. One had a mass of 71.5 kDa as determined by two-dimensional electrophoresis, matrix assisted laser desorption and ionization mass spectrometer (MALDI MS) analysis. The other was estimated to be 93 kDa by SDS-PAGE electrophoresis. The exposure of BSA to DHA also led to the generation of carbonyl groups. Oxygen radical scavengers could inhibit these modifications induced by DHA peroxidation. Furthermore, there was little difference of the peptides mass fingerprinting between the two kinds of modified high-molecular-weight proteins. These results suggest that oxygen radicals formed during lipid peroxidation are involved in the formation of protein derivatives. Our study may be important in the understanding the specific role of docosahexaenoic acid in the formation of modified proteins during aging and its related diseases.