Autophagic Survival Precedes Programmed Cell Death in Wheat Seedlings Exposed to Drought Stress.

Although studies have shown the concomitant occurrence of autophagic and programmed cell death (PCD) in plants, the relationship between autophagy and PCD and the factors determining this relationship remain unclear. In this study, seedlings of the wheat cultivar Jimai 22 were used to examine the occurrence of autophagy and PCD during polyethylene glycol (PEG)-8000-induced drought stress. Autophagy and PCD occurred sequentially, with autophagy at a relatively early stage and PCD at a much later stage. These findings suggest that the duration of drought stress determines the occurrence of PCD following autophagy. Furthermore, the addition of 3-methyladenine (3-MA, an autophagy inhibitor) and the knockdown of autophagy-related gene 6 (ATG6) accelerated PEG-8000-induced PCD, respectively, suggesting that inhibition of autophagy also results in PCD under drought stress. Overall, these findings confirm that wheat seedlings undergo autophagic survival under mild drought stress, with subsequent PCD only under severe drought.

Ordered carbon nanotubes-n-dodecyl tetraethylene monoether liquid crystal composites through phase separation induced by poly(ethylene glycol).

Carbon nanotubes (CNTs) were incorporated into a lyotropic liquid crystal (LLC) matrix at room temperature through spontaneous phase separation. The phase separation process occurred in n-dodecyl tetraethylene monoether (C12E4) solutions induced by the hydrophilic polymer, poly(ethylene glycol) (PEG). It was found that the molecular weight of PEG has a significant effect on the CNTs-C12E4 system, which not only influences the phase behavior of the system but also changes the properties of the CNTs-LLC composites. Polarized optical microscopy (POM) images, combined with small-angle X-ray scattering (SAXS) results, indicate that CNTs incorporate within the layers of the lamellar LLCs without destroying the structure of LLCs. Moreover, UV-vis absorption, Raman spectra and rheological measurements were performed to investigate the characteristic properties of the CNTs-LLC composites. This study not only gives a more comprehensive understanding of polymer-induced phase separation, but also expands the potential uses of CNTs-LLC composites in nanotechnology.

[Comparative analysis of the effect of autologous dentin particles and implantation of Bio-Oss on guided bone regeneration in the treatment of periodontal bone defects].

PURPOSE: To analyze the effect of autologous dentin particles and Bio-Oss bone powder implantation on guided bone regeneration in the treatment of periodontal bone defects. METHODS: Eighty-two patients with periodontal bone defect treated in Zhangye People's Hospital from May 2018 to May 2020 who underwent guided bone regeneration treatment were selected and divided into experimental group and control group according to random number table method, with 41 cases in each group. The control group was implanted with Bio-Oss during the operation, and the experimental group was implanted with autologous dentin particles during operation. Periodontal pocket depth and attachment loss, buccal soft tissue profile, buccal soft tissue thickness, red aesthetic score, success rate, and complications were compared between the two groups of patients. SPSS 22.0 software package was used for statistical analysis. RESULTS: Comparison within the group showed that 1 month and 1 year after operation, the periodontal pocket depth and attachment loss of the two groups were significantly reduced(P<0.05); and 1 year after operation, the periodontal pocket depth and attachment loss of the two groups were significantly lower than 1 month after surgery(P<0.05). Comparison between groups showed that 1 month and 1 year after operation, the periodontal pocket depth and attachment loss of the experimental group were significantly lower than those of the control group (P<0.05). Comparison within groups showed that 1 month and 1 year after operation, the buccal soft tissue profile of the two groups were significantly higher than that before operation (P<0.05); and 1 year after operation, the buccal soft tissue profile of the two groups were significantly lower than 1 month after operation. Comparison between groups showed that 1 year after operation, the buccal soft tissue profile of the experimental group was significantly higher than that of the control group (P<0.05). Comparison within groups showed that 1 month and 1 year after surgery, the thickness of the buccal soft tissue of the two groups were significantly higher than that before surgery. Comparison between groups showed that there was no significant difference in the thickness of the buccal soft tissue at each time point between the two groups(P>0.05). Comparison within groups showed that 1 month and 1 year after operation, the red aesthetic scores of patients in the two groups were significantly higher than those before operation (P<0.05); in addition, the red aesthetic scores of the two groups 1 year after surgery were significantly higher than those 1 month after surgery (P<0.05). Comparison between groups showed that 1 month and 1 year after surgery, the red aesthetic scores of the experimental group were significantly higher than those of the control group (P<0.05). One year after operation, the success rate of the experimental group and the control group were 90.24% (37/41) and 85.37% (35/41), respectively, and there was no significant difference between the two groups(P>0.05). There was no significant difference in the incidence of complications between the two groups(P>0.05). CONCLUSIONS: Autologous dentin particles can be used to guide bone regeneration to treat patients with periodontal bone defects, which can reduce the depth of periodontal pockets and loss of attachment, improve the buccal soft tissue profile and red aesthetic score, and the success rate is equivalent to implantation of Bio-Oss. Therefore, it is a safe and reliable treatment method.

New one-pot technique to introduce charged nanoparticles into a lyotropic liquid crystal matrix.

We present a new method to incorporate hydrophilic charged nanoparticles into the lyotropic liquid crystal (LLC) template. This method is based on the effect of the polymer-induced phase separation (PIPS) and consists of two steps. In the first step, the nanoparticles are mixed with a surfactant micellar solution. In the second step, upon addition of polymer, phase separation is induced and the LLC phase doped with the nanoparticles is formed. Columnar hexagonal and lamellar LLC templates are obtained with the PIPS method. The ordering of the LLC phase can be controlled by the amount of polymer added to induce phase separation. The method works both for the system of nonionic surfactants and polymers and ionic surfactants and polyelectrolytes. We demonstrate that the PIPS method enables the fabrication of the LLC templates doped with positively or negatively charged nanoparticles as well as with a mixture of oppositely charged nanoparticles in arbitrary proportions.

Incorporation of carbon nanotubes into a lyotropic liquid crystal by phase separation in the presence of a hydrophilic polymer.

Single-walled carbon nanotubes (SWNTs) were incorporated into a lyotropic liquid crystal (LLC) matrix formed by n-dodecyl octaoxyethene monoether (C(12)E(6)) at room temperature through spontaneous phase separation induced by nonionic hydrophilic polymer poly(ethylene glycol) (PEG). The quality of SWNTs/LLC composite was evaluated by polarized microscopy observations and small-angle X-ray scattering (SAXS) measurements. The results obtained clearly indicated that SWNTs have been successfully incorporated into the LLC matrix up to a considerable high content without destroying the LLC matrix, although interesting changes of the LLC matrix were also induced by SWNTs incorporation. By varying the ratio of PEG to C(12)E(6), the type of LLC matrix can be controlled from hexagonal phase to lamellar phase. Temperature was found to have a significant influence on the quality of SWNTs/LLC composite, and tube aggregation can be induced at higher temperature. When SWNTs were changed to multiwalled carbon nanotubes (MWNTs), they became difficult to be incorporated into LLC matrix because of an increase in the average tube diameter.

Effective Utilization of Carbohydrate in Corncob to Synthesize Furfuralcohol by Chemical-Enzymatic Catalysis in Toluene-Water Media.

In this study, carbohydrates (cellulose plus hemicellulose) in corncob were effectively converted furfuralcohol (FOL) via chemical-enzymatic catalysis in a one-pot manner. After corncob (2.5 g, dry weight) was pretreated with 0.5 wt% oxalic acid, the obtained corncob-derived xylose (19.8 g/L xylose) could be converted to furfural at 60.1% yield with solid acid catalyst SO42-/SnO2-attapulgite (3.6 wt% catalyst loading) in the water-toluene (3:1, v/v) at 170 °C for 20 min. Moreover, the oxalic acid-pretreated corncob residue (1.152 g, dry weight) was enzymatically hydrolyzed to 0.902 g glucose and 0.202 g arabinose. Using the corncob-derived glucose (1.0 mM glucose/mM furfural) as cosubstrate, the furfural liquor (48.3 mM furfural) was successfully biotransformed to FOL by recombinant Escherichia coli CCZU-A13 cells harboring an NADH-dependent reductase (SsCR) in the water-toluene (4:1, v/v) under the optimum conditions (50 mM PEG-6000, 0.2 mM Zn2+, 0.1 g wet cells/mL, 30 °C, pH 6.5). After the bioreduction for 2 h, FAL was completely converted to FOL. The FOL yield was obtained at 0.11 g FOL/g corncob. Clearly, this one-pot synthesis strategy shows high potential application for the effective synthesis of FOL.

Manipulation the properties of supramolecular hydrogels of α-cyclodextrin/Tyloxapol/carbon-based nanomaterials.

Supermolecular hydrogels were prepared by α-cyclodeatrin (α-CD) and Tyloxapol, which can be considered as an oligomer of the nonionic surfactant polyoxyethylene tert-octylphenyl ether (TX-100) with a polymerization degree below 7. Two carbon materials, graphene oxide (GO) and graphene, were mixed into the α-CD/Tyloxapol hydrogel to adjust the physicochemical properties of hydrogel. In order to get stable graphene dispersion and then mix it with α-CD/Tyloxapol hydrogel, both TX-100 and Tyloxapol were used to disperse graphene for comparison. Interestingly, it can be found that TX-100 could disperse graphene better than Tyloxapol owing to smaller molecular size of TX-100 compared with Tyloxapol. Then, both the α-CD/Tyloxapol/GO and α-CD/Tyloxapol/graphene hydrogels were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, small angle X-ray scattering (SAXS), X-ray diffraction (XRD) and rheological measurements. The results revealed that the addition of carbon materials into α-CD/Tyloxapol hydrogel can change their microstructures and the rheological properties. Furthermore, it can be confirmed that a little amount of carbon materials could induce fluorescence quenching sharply which could be a promising candidate for optical sensor.

Fluorescent oligomer as a chemosensor for the label-free detection of Fe(3+) and dopamine with selectivity and sensitivity.

In this article, a sensitive and selective turn-off fluorescence chemosensor, Tyloxapol (one kind of water soluble oligomer), was developed for the label-free detection of Fe(3+) ions in aqueous solution. Fluorescence (FL) experiments demonstrated that Tyloxapol was a sensitive and selective fluorescence sensor for the detection of Fe(3+) directly in water over a wide range of metal cations including Na(+), K(+), Ag(+), Hg(2+), Cd(2+), Co(2+), Cu(2+), Cr(3+), Mn(2+), Ba(2+), Zn(2+), Ni(2+), Mg(2+), Ca(2+), and Pb(2+). Moreover, the fluorescence intensity of Tyloxapol has shown a linear response to Fe(3+) in the concentration range of 0-100 µmol L(-1) with a detection limit of 2.2 µmol L(-1) in aqueous solution. Next, based on a competition mechanism, another turn-on sensing application of the Tyloxapol/Fe(3+) platform to probe dopamine (DA) against various other biological molecules such as other neurotransmitters or amino acids (norepinephrine bitartrate, acetylcholine chloride, alanine, valine, phenylalanine, tyrosine, leucine, glycine, histidine) were also investigated. It is expected that our strategy may offer a new approach for developing simple, cost-effective, rapid and sensitive sensors in biological and environmental applications.

Manipulation the behavior of supramolecular hydrogels of α-cyclodextrin/star-like block copolymer/carbon-based nanomaterials.

A new supramolecular hydrogel self-assembled between α-cyclodextrin (α-CD) and a star-like block copolymer AE73 was prepared. The cooperation effect of complexation of poly-(ethylene oxide) (PEO) segments with α-CD and the hydrophobic interaction between poly-(propylene oxide) (PPO) blocks resulted in the formation of the supramolecular hydrogel with a strong macromolecular network. Then two kinds of carbon materials (graphene and graphene oxide) were successfully incorporated into the above α-CD/AE73 hydrogel to further enhance the mechanical properties. The native hydrogel, as well as hybrid hydrogels, have been thoroughly characterized by using various microscopic techniques, including transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA). Our main purpose is to ascertain whether the properties of the obtained gels depend on these architectures. Interestingly, the phase behavior, the morphology and the mechanical strength of the native hydrogel can be successfully modulated by incorporating graphene and graphene oxide. Taking into account that both PEO/PPO copolymers and α-CD seem to be biocompatible, these gels can be promising for biomedical applications.

Collagen gel coating or cyclosporine A for improving histocompatibility of chicken calamus keratin.

OBJECTIVE: To improve the histocompatibility of chicken calamus keratin (CCK) graft by collagen-gel coating or using of cyclosporine A (CsA). METHODS: Thirty SD rats were equally randomized into 5 groups, and in 4 of them, CCK implantation into the bilateral erector spinae was performed on different treatment protocols. In group A, the rats received daily intraperitoneal injection of CsA (5 mg/kg) for two consecutive weeks after CCK implantation; in group B, CCK was soaked in CsA (2.5 mg/ml) solution at 4 degrees Celsius; for 48 h before grafting; in group C, CCK coated with collagen gel was grafted; and in group D, only CCK was implanted. Rats in the fifth group received only cutaneous incision as well as muscular dissection to serve as the blank control. CCK degradation and its effect on the surrounding tissues were observed at 2, 4 and 8 weeks after grafting. Immunohistochemistry was performed to identify T lymphocyte infiltration in the host tissues. RESULTS: All the rats survived the operation. Numerous macrophages, especially multinucleated giant cells occurred on the peripheral of the CCK grafts, and small degraded CCK pieces were observed in their cytoplasm. Only a few inflammatory cells were seen in the host tissues. At 2, 4 and 8 weeks after CCK implantation, only a few CD3-positive cells were found in all the groups, and in group A and B, the density of T lymphocytes was significantly lower than that in group D, and there was no significant difference between group A and the blank control group. CONCLUSIONS: CsA significantly improves the histocompatibility of CCK material, and short-term systemic CsA administration achieves the best results. Macrophages, especially multinucleated giant cells participate in CCK degradation in vivo.

[Preliminary study of chicken calamus conduit as a scaffold material for tissue engineering].

OBJECTIVE: To observe the unique structural features of chicken calamus keratin (CCK) conduit as a candidate scaffold material for tissue engineering and its in vivo degradation and histocompatibility after its implantation into living tissues. METHODS: Chicken calami were taken from healthy chickens and treated through sequential, controllable physical and biochemical procedures for preparation of three types of CCK conduits, namely CCK-I (mildly treated), CCK-II (moderately treated) and CCK-III (intensely treated). Light microscopy (LM) and scanning electron microscopy (SEM) were performed for morphological observation. Each of these three types of CCK pieces (experimental group) and the untreated ones (control group) was implanted into the dorsal muscular tissue on both sides of SD rats, respectively. Routine tissue sectioning and HE stain were performed to identify the morphological changes under light microscope. Each of the CCK threads (experimental group) and the untreated chicken calamus threads (control group) was also grafted within the sciatic nerve bundles of SD rats, respectively. RESULTS: The wall of the chicken calamus was composed of 4 compact parts from inside to outside on cross sections, namely the innermost basophilic homogenous coarse line, 3-5 layers of acidophilic corneum, 60-100 layers of circular keratin tracts containing massive pigment granules, and 10-20 outmost layers of keratin tracts with only a few pigment granules. The three-dimensional surface features of chicken calamus identified by SEM, as compared with untreated chicken calamus, was characterized by loose arrangement containing horizontal and vertical keratins with obvious pores of different sizes and depths on its surface. At 8 weeks after implantation into the muscular tissue in experimental groups, the CCK grafts were degraded into thin filaments or/and dispersed pieces and fine granules with the appearance of blood vessels, which facilitated the absorption of the degradation products; at 12 weeks, the grafts were markedly degraded into tiny fragments. In the control group, in contrast, the grafts remains intact throughout the experiment. After implantation of the material into the nerve bundles, similar cell infiltration and tissue responses to the grafts were observed as compared to those occur in intramuscular grafting. The degradation products did not seem to cause nerve tissue degeneration or necrosis. CONCLUSIONS: Fresh chicken calamus is a natural tube composed of multi-layered compact keratin tracts with pigment granules and small amount of matrix, and is non-absorbable in vivo, and therefore does not favor the purpose for use directly as a candidate biological scaffold. After proper treatment, the chicken calamus becomes loosely arranged porous material, and can be degraded and absorbed in vivo without resulting in tissue degradation or necrosis, suggesting its potential for applications in tissue engineering.

[Biological dressing with human hair keratin-collagen sponge-poly 2-hydroxyethyl methacrylate composite promotes burn wound healing in SD rats].

OBJECTIVE: To develop a composite material containing human hair keratin (HHK), collagen sponge (inner layer) and poly 2-hydroxyethyl methacrylate (PHEMA) film that allows sustained release of polydatin and test its effect as a biological dressing in promoting burn wound healing in SD rats. METHODS: Three HHK materials with fast, moderate, and low degradation rates were mixed at the ratio of 4:3:3 to prepare a reticular structure, which was processed into a composite material with bovine tendon-derived collagen sponge, and further complexed with HEMA film containing PD prepared by polymerization. Degree II burn wound was induced in SD rats by scalding and within postburn day 2-5, the wounds were cleansed and covered with the composite material or with glutaraldehyde-treated porcine skin (positive control). At week 1, 2, 4, 6 and 8 following wound dressing, 6 full-thickness skin samples were harvested from the wounds for histological observation and immunohistochemical detection of collagen and elastic fibers, and the wound healing time and healing rate were recorded. RESULTS: The prepared collagen sponge film was transparent and porous (50-300 microm in diameter) and allowed sustained PD release into normal saline within 48 h. Compared with the porcine skin, the composite material reduced exudation and maintained ideal moisture of the wound, and significantly shortened the wound healing time (P=0.000). On day 7, 14, and 21 following dressing, the composite material and porcine skin significantly increased the wound healing rate as compared with the negative control group (P=0.000), and on day 14, the composite achieved significantly greater healing rate than the porcine skin (P<0.05). CONCLUSION: HHK-collagen sponge-PHEMA/PD composite as a dressing material promotes burn wound healing in rats by allowing in vivo construction of tissue engineered epidermis. PHEMA is feasible for sustained drug delivery in this composite.