The Influence of the First-Stage DO Treatment of Palate Defect on Growth of Maxilla.

To study the influence of distraction osteogenesis (DO) on the maxillary growth as first-stage treatment of palatal defect. The uniform palate defect experimental animal models (21 miniature pigs) were established surgically. Then animals were randomly divided into negative control group (A, n = 6), conventional surgery group (B, n = 6), and distraction osteogenesis group (C, n = 9) respectively. The group A underwent none treatment as control group, the group B were undergoing a conventional defect repair surgery, and the group C were undergoing a distraction osteogenesis treatment. Cone beam computed tomography examination was performed monthly to analyze the growth of maxilla for 6 months. One pig of group C was randomly sacrificed at 2, 4, and 8 weeks after the completion of DO and the tissue of distraction gap was stained with hematoxylin-eosin and Masson staining. At the end of 6th months, all pigs were sacrificed and tissues of the surgical area were stained as previous described. The palate defect was repaired by the distraction osteogenesis with the successful bone formation on the distraction gap. Group A and group C kept a similar growth rate, but that of group B was relatively slow. Distraction osteogenesis is efficient and successful for closing the defect of palate and there is no significant disturbance on the subsequent growth of the maxilla.

Mechanochemically accessing a challenging-to-synthesize depolymerizable polymer.

Polymers with low ceiling temperatures (Tc) are highly desirable as they can depolymerize under mild conditions, but they typically suffer from demanding synthetic conditions and poor stability. We envision that this challenge can be addressed by developing high-Tc polymers that can be converted into low-Tc polymers on demand. Here, we demonstrate the mechanochemical generation of a low-Tc polymer, poly(2,5-dihydrofuran) (PDHF), from an unsaturated polyether that contains cyclobutane-fused THF in each repeat unit. Upon mechanically induced cycloreversion of cyclobutane, each repeat unit generates three repeat units of PDHF. The resulting PDHF completely depolymerizes into 2,5-dihydrofuran in the presence of a ruthenium catalyst. The mechanochemical generation of the otherwise difficult-to-synthesize PDHF highlights the power of polymer mechanochemistry in accessing elusive structures. The concept of mechanochemically regulating the Tc of polymers can be applied to develop next-generation sustainable plastics.

Nonsuture anastomosis of arteries and veins using the magnetic pinned-ring device: a histologic and scanning electron microscopic study.

BACKGROUND: The goal of this study was to evaluate the performance of the magnetic pinned-ring device for nonsuture vascular anastomosis. METHODS: The magnetic pinned-ring device consists of paired magnetic rings that are coated with titanium nitride and embedded in a polypropylene shell; the rings are equipped with alternately spaced holes and titanium pins. The vascular anastomosis procedure using the novel magnetic pinned-ring device was performed on 14 mongrel dogs, and the traditional hand-sewing technique was used on 14 additional dogs. In situ end-to-end anastomoses were performed in the femoral artery and the inferior vena cava. Patency was confirmed through ultrasonographic scans at different time points as late as 24 weeks after surgery. Gross observation, histological staining, and scanning electron microscopy were used to evaluate the results at 24 weeks postoperatively. RESULTS: The time required to perform the vascular anastomosis was significantly shorter for the magnetic device than for hand sewing. A continuity of re-endothelialization was confirmed in all anastomotic stomas after 24 weeks, and neither formation of aneurysms nor thickening of the vascular wall was noted. The re-endothelialization was smooth at the anastomotic site of the magnetic device, whereas hand sewing resulted in rough and uneven re-endothelialization and the presence of visible sutures. Moreover, the endothelial cells were regularly arranged at the anastomotic site of the magnetic device, whereas different-sized and irregularly aligned endothelial cells were present at the hand-sewn anastomotic site. Use of the magnetic device was associated with significantly decreased deposition of fibrotic collagen and depressed infiltration of inflammatory cells compared with use of the hand-sewing technique. CONCLUSIONS: The magnetic pinned-ring device offers a simple, fast, reliable, and efficacious technique for nonsuture vascular anastomosis. Use of this device shortens operation time, maintains a high patency rate, and improves the healing of vascular tissue.

Microplastics lag the leaching of phenanthrene in soil and reduce its bioavailability to wheat.

Microplastics wildly occur in soil and they can become the carriers of persistent contaminants. However, the influence of microplastics on polycyclic aromatic hydrocarbons vertical translocation in the soil system after rainfall is limitedly understood. Here, experiments were conducted to study the influence of polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) microplastics on the leaching behavior and bioavailability of phenanthrene (Phe). The adsorption capacity of phenanthrene on the microplastics followed the order of PS > PE > PVC. The Phe concentrations in the top soil layer after 15 days of leaching with water were 30.25, 28.32 and 27.25 mg kg-1 for the treatments of Phe-PS, Phe-PE and Phe-PVC respectively, which is consistent with the adsorption capacities of microplastics. The concentrations of Phe were correlated with the microplastic adsorption capacities at soil depths of 5-45 cm. Under long-term leaching, Phe could reach the deeper soil layer. Phe concentrations significantly decreased in the leachate over time. Phe concentrations in wheat had a positive correlation with that in leachate/leached top soil layer. Our findings are beneficial to accurately evaluate the ecological risk of the combined contamination of PAHs and microplastics, and improve the understanding of the environmental behaviors of different microplastics.

Esophageal magnetic compression anastomosis in dogs.

BACKGROUND: Magnetic compression anastomosis (MCA) is a novel suture-free reconstruction of the digestive tract. It has been used in gastrointestinal anastomosis, jejunal anastomosis, cholangioenteric anastomosis and so on. The traditional operative outcomes of congenital esophageal atresia and benign esophageal stricture are poor, and there are too many complications postoperatively. AIM: To test MCA technology to reconstruct the esophagus in dogs, prior to studying the feasibility and safety of MCA in humans. METHODS: Thirty-six dogs were randomized into either the study or control group (n = 18 per group). The dogs in the study group were subjected to end-to-end esophageal anastomosis with the magnetic compression device, while those in the control group underwent hand-sewn anastomosis with 4-0 absorbable multifilament Vicryl. We used interrupted single-layer inverting sutures. The anastomosis time, gross appearance, weight and pathology of the anastomosis were evaluated at one month, three months and six months postoperatively. RESULTS: The anastomosis time of the MCA group was shorter than that of the hand-sewn group (7.5 ± 1.0 min vs 12.5 ± 1.8 min, P < 0.01). In the MCA group, X-ray examination was performed every day to locate the magnetic device in the esophagus before the magnetic device fell off from the esophagus. In the hand-sewn group, dogs did not undergo X-ray examination. One month after the surgeries, the mean weight of the dogs in the hand-sewn group had decreased more than that of the dogs in the MCA group (11.63 ± 0.71 kg vs 12.73 ± 0.80 kg, P < 0.05). At 3 mo and 6 mo after the operation, the dogs' weights were similar between the two groups (13.75 ± 0.84 kg vs 14.03 ± 0.82 kg, 14.93 ± 0.80 kg vs 15.44 ± 0.47 kg). The number of inflammatory cells in MCA group was lower than that in hand-sewn group on 1 mo after operation. CONCLUSION: MCA is an effective and safe method for esophageal reconstruction. The anastomosis time of the MCA group was less than that of the hand-sewn group. This study shows that MCA technology may be applied to human esophageal reconstruction, provided these favorable results are confirmed by more publications.

Microplastic particles alter wheat rhizosphere soil microbial community composition and function.

The wide existence of microplastics (MPs) in the terrestrial systems is proved by -many studies, and their presence could potentially change the soil chem-physical properties and processes. Various types of microplastics may have different behaviors, inducing distinct effects on the soil ecosystems. However, the knowledge of microplastic impacts on rhizosphere soil bacterial community structure is limited. In our study, three types of microplastics, i.e., polyethylene (PE), polyvinylchloride (PVC) and polystyrene (PS), with the same particle size (200 µm) and concentration (2%) were used to investigate their influences on the rhizosphere soil bacterial communities. Results revealed that the alpha diversities (richness, evenness and diversity) of microbiota in the rhizosphere soil were variously decreased by the microplastics, especially the PE MPs. The relative abundance of some various phyla and genera related to pollution degradation was miscellaneously increased, indicating that the MPs with different characterizations may have miscellaneous biodegradation pathways. Moreover, the PICRUSt2 analysis demonstrated that PS decreased most functional category levels and led to a decrease of bacterial genus number, however, PE and PVC improved metabolic pathways and xenobiotics biodegradation and metabolism. Our findings offer important knowledge of how the microplastics with different characterizations influence rhizosphere soil bacterial communities and their related function.

Microbial Metabolite Inspired ß-Peptide Polymers Displaying Potent and Selective Antifungal Activity.

Potent and selective antifungal agents are urgently needed due to the quick increase of serious invasive fungal infections and the limited antifungal drugs available. Microbial metabolites have been a rich source of antimicrobial agents and have inspired the authors to design and obtain potent and selective antifungal agents, poly(DL-diaminopropionic acid) (PDAP) from the ring-opening polymerization of ß-amino acid N-thiocarboxyanhydrides, by mimicking ε-poly-lysine. PDAP kills fungal cells by penetrating the fungal cytoplasm, generating reactive oxygen, and inducing fungal apoptosis. The optimal PDAP displays potent antifungal activity with minimum inhibitory concentration as low as 0.4 µg mL-1 against Candida albicans, negligible hemolysis and cytotoxicity, and no susceptibility to antifungal resistance. In addition, PDAP effectively inhibits the formation of fungal biofilms and eradicates the mature biofilms. In vivo studies show that PDAP is safe and effective in treating fungal keratitis, which suggests PDAPs as promising new antifungal agents.

The joint toxicity of polyethylene microplastic and phenanthrene to wheat seedlings.

Due to wide distribution, easy production, and difficult degradation, microplastic pollution has become a new environmental problem that has attracted worldwide attention. However, there is little information about the effects of microplastics in soil and their combined pollution with other organic pollutants on crop growth. In this study, we conducted soil culture experiments to evaluate the effects of polyethylene microplastics (PE-MPs) (0.5%, 1%, 2%, 5%, 8% w/w) individual and combined with phenanthrene (100 mg kg-1) on wheat growth for 15 days. Under PE-MPs alone and combined with phenanthrene exposure, dose-dependent toxicities in biomass, shoot height and root length were observed. Over 1% PE-MPs stimulate wheat root elongation. Compared with single phenanthrene treatment, the co-contamination of PE-MPs and phenanthrene reduces the accumulation of phenanthrene in wheat roots and leaves. In the range of 0-5%, the activity of wheat root antioxidant enzymes increases with increasing PE-MP concentration; but both phenanthrene and high concentrations (8%) of PE-MPs cause damage to the antioxidant system in wheat roots. In the presence or absence of phenanthrene, the photosynthetic pigment concentration of wheat leaves shows a dual concentration effect of low promotion and high inhibition under PE-MPs stress. The single pollution of PE-MPs destroys the photosynthetic system of wheat leaves, while the co-contamination of PE-MPs and phenanthrene exacerbates this destruction. Therefore, the co-contamination of PE-MPs and phenanthrene causes greater damage to wheat growth. Our findings can help to evaluate the individual and comprehensive toxicity of microplastics and polycyclic aromatic hydrocarbons to crops.

Effect of poly(ɛ-caprolactone-co-L-lactide) on thermal and functional properties of poly(L-lactide).

A blend of poly(L-lactide) (PLLA) with star-shaped poly(ɛ-caprolactone-co-L-lactide) (s-PCLA) at different contents (PLLA/s-PCLA=100/0, 90/10, 80/20, and 70/30, w/w) were prepared by torque rheometer. Thermal and functional properties of the blends were investigated by FTIR, SEM, DSC, TGA, DMA, tensile, optical, and water vapor permeability tests. FTIR results showed that intermolecular hydrogen bonds existed between two components in the blends. SEM indicated that PLLA and s-PCLA showed limited miscibility. DSC showed that Tg occurred at lower temperatures in the PLLA/s-PCLA blends than in neat PLLA, and the crystallinity of PLLA phase increased by the presence of s-PCLA in the PLLA/s-PCLA blends. TGA indicated that s-PCLA improved the thermal stability of the PLLA/s-PCLA blends. DMA results revealed that the storage modulus of the composites decreased with respect to the pure polymer. The result of tensile tests suggested that the PLLA/s-PCLA blends showed better elongation at break than neat PLLA. The effect of s-PCLA on the color and opacity of films could be considered as negligible. The WVP of PLLA/s-PCLA blend films increased with the increase in s-PCLA, and they were still lower than that of commercial LDPE films.