Collective Cell Behavior in Mechanosensing of Substrate Thickness.

Extracellular matrix stiffness has a profound effect on the behavior of many cell types. Adherent cells apply contractile forces to the material on which they adhere and sense the resistance of the material to deformation-its stiffness. This is dependent on both the elastic modulus and the thickness of the material, with the corollary that single cells are able to sense underlying stiff materials through soft hydrogel materials at low (<10 µm) thicknesses. Here, we hypothesized that cohesive colonies of cells exert more force and create more hydrogel deformation than single cells, therefore enabling them to mechanosense more deeply into underlying materials than single cells. To test this, we modulated the thickness of soft (1 kPa) elastic extracellular-matrix-functionalized polyacrylamide hydrogels adhered to glass substrates and allowed colonies of MG63 cells to form on their surfaces. Cell morphology and deformations of fluorescent fiducial-marker-labeled hydrogels were quantified by time-lapse fluorescence microscopy imaging. Single-cell spreading increased with respect to decreasing hydrogel thickness, with data fitting to an exponential model with half-maximal response at a thickness of 3.2 µm. By quantifying cell area within colonies of defined area, we similarly found that colony-cell spreading increased with decreasing hydrogel thickness but with a greater half-maximal response at 54 µm. Depth-sensing was dependent on Rho-associated protein kinase-mediated cellular contractility. Surface hydrogel deformations were significantly greater on thick hydrogels compared to thin hydrogels. In addition, deformations extended greater distances from the periphery of colonies on thick hydrogels compared to thin hydrogels. Our data suggest that by acting collectively, cells mechanosense rigid materials beneath elastic hydrogels at greater depths than individual cells. This raises the possibility that the collective action of cells in colonies or sheets may allow cells to sense structures of differing material properties at comparatively large distances.

Characterization of New PEEK/HA Composites with 3D HA Network Fabricated by Extrusion Freeforming.

Addition of bioactive materials such as calcium phosphates or Bioglass, and incorporation of porosity into polyetheretherketone (PEEK) has been identified as an effective approach to improve bone-implant interfaces and osseointegration of PEEK-based devices. In this paper, a novel production technique based on the extrusion freeforming method is proposed that yields a bioactive PEEK/hydroxyapatite (PEEK/HA) composite with a unique configuration in which the bioactive phase (i.e., HA) distribution is computer-controlled within a PEEK matrix. The 100% interconnectivity of the HA network in the biocomposite confers an advantage over alternative forms of other microstructural configurations. Moreover, the technique can be employed to produce porous PEEK structures with controlled pore size and distribution, facilitating greater cellular infiltration and biological integration of PEEK composites within patient tissue. The results of unconfined, uniaxial compressive tests on these new PEEK/HA biocomposites with 40% HA under both static and cyclic mode were promising, showing the composites possess yield and compressive strength within the range of human cortical bone suitable for load bearing applications. In addition, preliminary evidence supporting initial biological safety of the new technique developed is demonstrated in this paper. Sufficient cell attachment, sustained viability in contact with the sample over a seven-day period, evidence of cell bridging and matrix deposition all confirmed excellent biocompatibility.

Prevalence and types of drug-resistant variants in Chinese patients with acute hepatitis B.

The presence of therapy-associated hepatitis B virus (HBV) variants is the main drawback of antiviral therapy for HBV infection. Moreover, drug-resistant variants are more insensitive to a second agent and more therapy-associated mutations will be present. To apply better nucleos(t)ide analogues (NA) and reduce the occurrence of resistance, the prevalence and types of drug-resistant mutations in acute hepatitis B patients were investigated in this study. One hundred three HBV DNA-positive patients with symptomatic acute hepatitis B that were observed from 2011 to 2013 were enrolled. Direct polymerase chain reaction sequencing was used firstly to screen HBV reverse-transcriptase domain to detect HBV mutants. Five lamivudine-resistant variants were identified. Clonal sequencing was performed for 5 resistance-positive samples and 10 other random samples. Interestingly, all detected samples harbored drug-resistant mutations, although with different percentage. Thirteen harbored lamivudine-related alone (five) or together with other NA related mutations (five with adefovir, one with entecavir, and one with telbivudine), and two of them harbored adefovir-related mutations. Also, mutations associated with four currently used NA were all detected, and the frequency is in accordance with the popularity of NA used in clinical practice. These data suggest that drug-resistant variants are present in patients with acute hepatitis B and NA should be applied more carefully for chronic hepatitis B patients developed from acute hepatitis B.

Biomechanical feasibility of non-locking system in patient-specific mandibular reconstruction using fibular free flaps.

Mandibular reconstruction with free fibular flaps is frequently used to restore segmental defects. The osteosythesis, including locking and non-locking plate/screw systems, is essential to the mandibular reconstruction. Compared with the non-locking system that requires good adaption between plate and bone, the locking system appears to present a better performance by locking the plate to fixation screws. However, it also brings about limitations on screw options, a higher risk of screw failure, and difficulties in screw placement. Furthermore, its superiority is undermined by the advancing of patient-specific implant design and additive manufacturing. A customized plate can be designed and fabricated to accurately match the mandibular contour for patient-specific mandibular reconstruction. Consequently, the non-locking system seems more practicable with such personalized plates, and its biomechanical feasibility ought to be estimated. Finite element analyses of mandibular reconstruction assemblies were conducted for four most common segmental mandibular reconstructions regarding locking and non-locking systems under incisal biting and right molars clenching, during which the influencing factor of muscles' capacity was introduced to simulate the practical loadings after mandibular resection and reconstruction surgeries. Much higher, somewhat lower, and similar maximum von Mises stresses are separately manifested by the patient-specific mandibular reconstruction plate (PSMRP), fixation screws, and reconstructed mandible with the non-locking system than those with the locking system. Equivalent maximum displacements are identified between PSMRPs, fixation screws, and reconstructed mandibles with the non-locking and locking system in all four reconstruction types during two masticatory tasks. Parallel maximum and minimum principal strain distributions are shared by the reconstructed mandibles with the non-locking and locking system in four mandibular reconstructions during both occlusions. Conclusively, it is feasible to use the non-locking system in case of patient-specific mandibular reconstruction with fibular free flaps based on the adequate safety, comparable stability, and analogous mechanobiology it presents compared with the locking system in a more manufacturable and economical way.

Biomechanical validation of structural optimized patient-specific mandibular reconstruction plate orienting additive manufacturing.

BACKGROUND AND OBJECTIVE: Owing to the unexpected in vivo fracture failure of the original design, structural optimized patient-specific mandibular reconstruction plates (PSMRPs) were created to boost the biomechanical performance of bridging segmental bony defect in the mandibular reconstruction after tumor resection. This work aimed to validate the biomechanical benefit of the structural optimized PSMRPs relative to the original design and compare the biomechanical performance between PSMRP1 with generic contour customization and PSMRP2 with a tangent arc upper margin in mandibular angle region. METHODS: Finite Element Analysis (FEA) was used to evaluate the biomechanical behavior of mandibular reconstruction assemblies (MRAs) concerning these two structural optimized PSMRPs by simulating momentary left group clenching and incisal clenching tasks. Bonded contact was set between mandibular bone and fixation screws and between PSMRP and fixation screws in the MRA, while the frictionless connection was allocated between mandibular bone and PSMRP. The loads were applied on four principal muscles, including masseter, temporalis, lateral and medial pterygoid, whose magnitudes along the three orthogonal directions. The mandibular condyles were retrained in all three directions, and either the left molars or incisors area were restrained from moving vertically. RESULTS: The peak von Mises stresses of structural optimized PSMRPs (264 MPa, 296 MPa) were way lower than that of the initial PSMRP design (393 MPa), with 33 and 25% reduction during left group clenching. The peak magnitude of von Mises stress, minimum principal stress, and maximum principal strain of PSMRP1 (264 MPa, 254 MPa; -297 MPa, -285 MPa; 0.0020, 0.0020) was lower than that of PSMRP2 (296 MPa, 286 MPa; -319 MPa, -306 MPa; 0.0022, 0.0020), while the peak maximum principal stress of PSMRP1 (275 MPa, 257 MPa) was higher than that of PSMRP2 (254 MPa, 235 MPa) during both left group clenching and incisal clenching tasks. CONCLUSIONS: The structural optimized PSMRPs reveal their biomechanical advantage compared with the original design. The PSMRP1 presents better biomechanical performance to the patient-specific mandibular reconstruction than PSMRP2 as a result of its superior safety, preferable flexibility, and comparable stability. The PSMRP2 provides biomechanical benefit in reducing the maximum tension than PSMRP1, indicated by lower peak maximum principal stress, through tangent arc upper margin in mandibular angle region.

Concurrence of Talaromycosis and Kaposi Sarcoma in an HIV-Infected Patient: A Case Report.

BACKGROUND: Concurrence of talaromycosis, an infection caused by the opportunistic fungal pathogen Talaromyces marneffei and Kaposi sarcoma, a common vascular tumor, is a rare but severe medical condition in patients infected with the human immunodeficiency virus (HIV). Despite poor outcomes, the clinical characteristics and management strategies for HIV-infected patients with comorbid Kaposi sarcoma and talaromycosis have not been well documented. CASE PRESENTATION: A 33-year-old HIV-positive male patient presented to the Department of Infectious Diseases at Wenzhou Central Hospital with cough, sputum expectoration, hemoptysis, rashes on the feet and violaceous plaques in the oral cavity. Chest computed tomography (CT) showed bilateral nodules, patchy shadows and lymphadenectasis. Skin biopsy and histopathological examination indicated Kaposi sarcoma. T. marneffei was isolated from blood cultures and suggested talaromycosis. The patient's overall conditions significantly improved following initiation of combination antiretroviral therapy (cART) and chemotherapy for Kaposi sarcoma and antifungal treatment for talaromycosis. CONCLUSION: Severe medical conditions such as Kaposi sarcoma and talaromycosis may coexist in HIV-infected patients and pose an increased risk of mortality. Etiological diagnosis and treatment are the keys to the successful management of HIV-infected patients with these concurrent conditions.

Biomechanical comparison of locking and non-locking patient-specific mandibular reconstruction plate using finite element analysis.

Patient-specific mandibular reconstruction plate (PSMRP), as one of the patient-specific implants (PSIs), offers a host of benefits to mandibular reconstruction. Due to the limitation of fabricating screw hole threads in the PSMRP, 3D printed PSMRP is applied to the non-locking system directly in the mandibular reconstruction with bone graft regardless of the locking system. Since the conventional manual-bending reconstruction plate (CMBRP) provides better fixation in the locking system, it needs to be validated whether the locking PSMRP performs better than the non-locking PSMRP in the patient-specific mandibular reconstruction. Thereupon, the purpose of this study was to compare the biomechanical behavior between the locking and non-locking PSMRP. Finite element analysis (FEA) was used to conduct the biomechanical comparison between the locking PSMRP and non-locking PSMRP by simulating the momentary incisal clenching through static structural analysis. Mandible was reconstructed through the virtual surgical planning, and subsequently a 3D model of mandibular reconstruction assembly, including reconstructed mandible, PSMRP, and fixation screws, was generated and meshed for the following FEA simulations. In the form of equivalent von Mises stress, equivalent elastic strain, and total deformation, the locking PSMRP demonstrated its higher strengths of preferable safety, desirable flexibility, and anticipated stability compared with the non-locking PSMRP, indicated by much lower maximum stress, lower maximum strain and equivalent displacement. Locking PSMRP/screw system provides a better fixation effect to the patient-specific mandibular reconstruction than the non-locking one as a result of its productive fixation nature. FEA plays a paramount role in pre-validating the design of PSMRP through the biomechanical behavior evaluation in static structural analysis.

Preclinical study of additive manufactured plates with shortened lengths for complete mandible reconstruction: Design, biomechanics simulation, and fixation stability assessment.

BACKGROUND: A combination of short titanium plates fabricated using additive manufacturing (AM) provides multiple advantages for complete mandible reconstruction, such as the minimisation of inherent implant deformation formed during AM and the resulting clinical impact, as well as greater flexibility for surgical operation. However, the biomechanical feasibility of this strategy is still unclear, and therefore needs to be explored. METHOD: Three different combinations of short mandible reconstruction plates (MRPs) were customised considering implant deformation during the AM process. The resulting biomechanical performance was analysed by finite element analysis (FEA) and compared to a conventional single long MRP. RESULTS: The combination of a long plate and a short plate (Design 3 [LL61 mm/RL166 mm]) shows superior biomechanical properties to the conventional single long plate (Design 1 [TL246 mm]) and reveals the most reliable fixation stability among the three designs with short plates. Compared to conventional Design 1, Design 3 provides higher plate safety (maximum tensile stress on plates reduced by 6.3%), lower system fixation instability (relative total displacement reduced by 41.4%), and good bone segment stability (bone segment dislocation below 42.1 µm) under masticatory activities. CONCLUSIONS: Preclinical evidence supports the biomechanical feasibility of using short MRPs for complete mandible reconstruction. Furthermore, the results could also provide valuable information when treating other large-sized bone defects using short customised implants, expanding the potential of AM for use in implant applications.

Fused Deposition Modeling of Poly (lactic acid)/Macadamia Composites-Thermal, Mechanical Properties and Scaffolds.

In this work Macadamia nutshell (MS) was used as filler in fused deposition modeling (FDM) of Poly (lactic acid) (PLA) composites filaments. Composites containing MS both treated and untreated with alkali and silane were investigated by means of Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), Thermogravimetry (TG), scanning electron microscopy (SEM). The results showed that the treated MS composites had better thermal stability. Furthermore, compression tests were carried out. The PLA with 10 wt% treated MS composite was found possessing the best mechanical properties which was almost equivalent to that of the pure PLA. Finally, porous scaffolds of PLA/10 wt% treated MS were fabricated. The scaffolds exhibited various porosities in range of 30-65%, interconnected holes in size of 0.3-0.5 mm, micro pores with dimension of 0.1-1 µm and 37.92-244.46 MPa of elastic modulus. Those values indicated that the FDM of PLA/MS composites have the potential to be used as weight lighter and structural parts.

Hydroxyethyl Chitosan-Reinforced Polyvinyl Alcohol/Biphasic Calcium Phosphate Hydrogels for Bone Regeneration.

Fabrication of reinforced scaffolds for bone regeneration remains a significant challenge. The weak mechanical properties of the chitosan (CS)-based composite scaffold hindered its further application in clinic. Here, to obtain hydroxyethyl CS (HECS), some hydrogen bonds of CS were replaced by hydroxyethyl groups. Then, HECS-reinforced polyvinyl alcohol (PVA)/biphasic calcium phosphate (BCP) nanoparticle hydrogel was fabricated via cycled freeze-thawing followed by an in vitro biomineralization treatment using a cell culture medium. The synthesized hydrogel had an interconnected porous structure with a uniform pore distribution. Compared to the CS/PVA/BCP hydrogel, the HECS/PVA/BCP hydrogels showed a thicker pore wall and had a compressive strength of up to 5-7 MPa. The biomineralized hydrogel possessed a better compressive strength and cytocompatibility compared to the untreated hydrogel, confirmed by CCK-8 analysis and fluorescence images. The modification of CS with hydroxyethyl groups and in vitro biomineralization were sufficient to improve the mechanical properties of the scaffold, and the HECS-reinforced PVA/BCP hydrogel was promising for bone tissue engineering applications.

Strategy for Controlling the Properties of Bioactive Poly-Ether-Ether-Ketone/Hydroxyapatite Composites for Bone Tissue Engineering Scaffolds.

A strategy for the preparation of bioactive poly-ether-ether-ketone/hydroxyapatite (PEEK/HA) composites was proposed in this study with the aim of controlling the biological and mechanical properties of different parts of the composites. The strategy integrated solvent-based extrusion freeforming 3D printing technology in order to print high-resolution HA scaffolds and compression molding processes for the production of bioactive PEEK/HA composites. To this end, an optimized model, established using response surface methodology, was employed to optimize the extrusion process parameters on the basis of accurate characterization of the extrusion pressure, and the effects of the filament/pore sizes on the PEEK infiltration depth into the HA scaffold were investigated. The results of scanning electron microscopy and computed tomography analyses revealed that the PEEK/HA composites exhibited a uniform microstructure and a good interface between the HA filaments and the PEEK matrix following the optimization of the process parameters. The HA scaffolds were fully infiltrated by PEEK in both vertical and lateral directions with an infiltration depth of 3 mm while maintaining the HA network structure and uniformity. The biological and mechanical performance test results validated that the PEEK/HA composites possessed excellent biocompatibility as well as yields and compressive strengths within the range of human cortical bone suitable for load-bearing applications.

Investigation on the orientation dependence of elastic response in Gyroid cellular structures.

Materials used for hard tissue replacement should match the elastic properties of human bone tissue. Therefore, cellular structures are more favourable for the use of implants than solid materials for their custom-designed mechanical properties. The superimposed load from various directions in vivo makes uniaxial compression testing insufficient for describing the mechanical responses. In this paper, the rotational symmetry of Gyroid cellular structure (GCS) was discussed. An approach using structural simplification and analytical solution was presented to investigate the relationship between Young's modulus and volume fraction, as well as the orientation dependence of the mechanical responses for GCS loaded in various orientations. It is concluded that the analytical solution is reasonable for a low volume fraction, through the comparison between analytical results, finite element (FE) and experimental data. Gained polar diagrams illustrate the anisotropic property of GCS and also confirm the superiority for their stable mechanical responses of diverse loading directions.

Development of chitosan/gelatin hydrogels incorporation of biphasic calcium phosphate nanoparticles for bone tissue engineering.

The chitosan/gelatin hydrogel incorporated with biphasic calcium phosphate nanoparticles (BCP-NPs) as scaffold (CGB) for bone tissue engineering was reported in this article. Such nanocomposite hydrogels were fabricated by using cycled freeze-thawing method, of which physicochemical and biological properties were regulated by adjusting the weight ratio of chitosan/gelatin/BCP-NPs. The needle-like BCP-NPs were dispersed into composites uniformly, and physically cross-linked with chitosan and gelatin, which were identified via Scanning Electron Microscope (SEM) images and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. The porosity, equilibrium swelling ratio, and compressive strength of CGB scaffolds were mainly influenced by the BCP-NPs concentration. In vitro degradation analysis in simulated body fluids (SBF) displayed that CGB scaffolds were degraded up to at least 30 wt% in one month. Also, CCK-8 analysis confirmed that the prepared scaffolds had a good cytocompatibility through in culturing with bone marrow mesenchymal stem cells (BMSCs). Finally, In vivo animal experiments revealed that new bone tissue was observed inside the scaffolds, and gradually increased with increasing months, when implanted CGB scaffolds into large necrotic lesions of rabbit femoral head. The above results suggested that prepared CGB nanocomposites had the potential to be applied in bone tissue engineering.

Influence of Carbon Nanoparticle Addition (and Impurities) on Selective Laser Melting of Pure Copper.

The addition of 0.1 wt % carbon nanoparticles significantly improved the optical absorption and flowability of gas-atomized copper powder. This facilitated selective laser melting (SLM) by reducing the required laser energy density to obtain 98% dense parts. Moreover, the carbon addition led to an in situ de-oxidation of the copper parts during the SLM process. The properties of the as-built copper parts were limited to a tensile strength of 125 MPa, a ductility of 3%, and an electrical conductivity of 22.7 × 106 S/m, despite the advantageous effect of carbon on the powder characteristics and SLM behavior. The modest mechanical properties were associated with the segregation of carbon nanoparticles and other impurities, such as phosphorus and oxygen along grain boundaries of epitaxially grown grains. Whereas, the low electrical conductivity was mainly attributed to the phosphorus impurity in solid-solution with copper.

A Comprehensive Evaluation of Xpert MTB/RIF Assay With Bronchoalveolar Lavage Fluid as a Single Test or Combined With Conventional Assays for Diagnosis of Pulmonary Tuberculosis in China: A Two-Center Prospective Study.

Introduction: The Xpert MTB/RIF is recommended by the World Health Organization as a first line rapid test for the diagnosis of pulmonary tuberculosis (TB); however, China does not routinely use this test, partially due to the lack of a sufficient number of systematic evaluations of this assay in local patients. The aims of this study were to comprehensively assess the diagnostic performance of Xpert MTB/RIF, either alone or in combination with conventional assays for the diagnosis of pulmonary TB in adult Chinese patients. Methods: Xpert MTB/RIF tests were performed in 190 adult patients with suspected pulmonary TB, using bronchoalveolar lavage fluid (BALF) as test specimens. In parallel, conventional tests were carried out using the same BALF samples. Using two different reference standards, the performance of Xpert MTB/RIF, conventional assays and their combinations were evaluated. Results: Using mycobacterial culture as the reference comparator, Xpert MTB/RIF was found to be superior to smear-microscopy in detecting Mycobacterium tuberculosis. When final diagnosis, based on clinical criteria, was employed as the reference standard, Xpert MTB/RIF showed an even higher accuracy of 72.1%, supported by a sensitivity of 61.1% and specificity of 96.6%. Xpert MTB/RIF also demonstrated a powerful capability to identify pulmonary TB cases undetected by culture or smear-microscopy. Combining smear-microscopy and Xpert MTB/RIF was found to be the most accurate early predictor for pulmonary TB. Rifampicin resistance reported by Xpert MTB/RIF slightly deviated from that by phenotypic antibiotic susceptibility testing and requires further study with a larger sample size. Conclusion: This two-center prospective study highlights the value of Xpert MTB/RIF with BALF in diagnosing pulmonary TB in adult Chinese patients. These findings might contribute to the optimization of current diagnostic algorithms for pulmonary TB in China.

Fine ceramic lattices prepared by extrusion freeforming.

Fine ceramic lattices with spatial resolution <100 microm and having precise dimensions and intricate hierarchical structure are fabricated by extrusion freeforming, a rapid prototyping technique, which allows overall shape and structure to be controlled by computer. The procedure can be used for any fine ceramic powder and can therefore find applications as diverse as microwave and terahertz metamaterials (artificial crystals), hard tissue scaffolds, microfluidic devices, and metal matrix composite preforms. The examples presented here are calcium phosphate lattices with three structure levels: submicron pores, which enhance cell-surface interactions, pores of tens of microns to encourage bone ingrowth, and corridors (hundreds of microns) for vascularization. With controlled pore structures on these scales, the lattices are expected to provide customized biological, mechanical, and geometrical requirements.

Antibiotic regimen based on population analysis of residing persister cells eradicates Staphylococcus epidermidis biofilms.

Biofilm formation is a major pathogenicity strategy of Staphylococcus epidermidis causing various medical-device infections. Persister cells have been implicated in treatment failure of such infections. We sought to profile bacterial subpopulations residing in S. epidermidis biofilms, and to establish persister-targeting treatment strategies to eradicate biofilms. Population analysis was performed by challenging single biofilm cells with antibiotics at increasing concentrations ranging from planktonic minimum bactericidal concentrations (MBCs) to biofilm MBCs (MBCbiofilm). Two populations of "persister cells" were observed: bacteria that survived antibiotics at MBCbiofilm for 24/48 hours were referred to as dormant cells; those selected with antibiotics at 8 X MICs for 3 hours (excluding dormant cells) were defined as tolerant-but-killable (TBK) cells. Antibiotic regimens targeting dormant cells were tested in vitro for their efficacies in eradicating persister cells and intact biofilms. This study confirmed that there are at least three subpopulations within a S. epidermidis biofilm: normal cells, dormant cells, and TBK cells. Biofilms comprise more TBK cells and dormant cells than their log-planktonic counterparts. Using antibiotic regimens targeting dormant cells, i.e. effective antibiotics at MBCbiofilm for an extended period, might eradicate S. epidermidis biofilms. Potential uses for this strategy are in antibiotic lock techniques and inhaled aerosolized antibiotics.

The design of scaffolds for use in tissue engineering. Part II. Rapid prototyping techniques.

Tissue engineering (TE) is an important emerging area in biomedical engineering for creating biological alternatives for harvested tissues, implants, and prostheses. In TE, a highly porous artificial extracellular matrix or scaffold is required to accommodate mammalian cells and guide their growth and tissue regeneration in three-dimension (3D). However, existing 3D scaffolds for TE proved less than ideal for actual applications because they lack mechanical strength, interconnected channels, and controlled porosity or pores distribution. In this paper, the authors review the application and advancement of rapid prototyping (RP) techniques in the design and creation of synthetic scaffolds for use in TE. We also review the advantages and benefits, and limitations and shortcomings of current RP techniques as well as the future direction of RP development in TE scaffold fabrication.

Regulation of an antioxidant blend on intestinal redox status and major microbiota in early weaned piglets.

OBJECTIVE: According to the "antioxidants network" theory, the present study was conducted to evaluate the regulation of an antioxidant blend on intestinal redox status and major microbiota of early-weaned piglets. METHODS: Piglets from 15 litters were randomly allocated by litter to the control group (suckling normally, fed the basal diet, n = 5), the weaning group (weaned at age 21 d, fed the basal diet, n = 5), and the repair group (weaned at age 21 d, fed the basal diet supplemented with an antioxidant blend, n = 5). The redox status and major microbiota in jejunum and colon tracts of 24-d-old piglets were detected, respectively. RESULTS: Early weaning resulted in significant decreases in jejunum and colon antioxidant capacities, Lactobacillus and Bifidobacterium counts, and significant increases in levels of jejunum malondialdehyde, colon hydroxyl radicals, jejunum and colon H2O2, and Escherichia coli counts in piglets. The observed imbalance of the intestinal redox status and microbiota was significantly restored by the antioxidant blend. Interestingly, intestinal selected antioxidative items presented a positive correlation with potential beneficial bacteria and a negative correlation with E. coli. Nevertheless, selected oxidative items and the bacteria presented an inverse relationship in piglets. CONCLUSION: Supplementation of the antioxidant blend effectively restored intestinal redox status and microbiota balance in the porcine intestine in response to early weaning stress, enhancing intestinal health and function of piglets.

Hope versus hype: what can additive manufacturing realistically offer trauma and orthopedic surgery?

Additive manufacturing (AM) is a broad term encompassing 3D printing and several other varieties of material processing, which involve computer-directed layer-by-layer synthesis of materials. As the popularity of AM increases, so to do expectations of the medical therapies this process may offer. Clinical requirements and limitations of current treatment strategies in bone grafting, spinal arthrodesis, osteochondral injury and treatment of periprosthetic joint infection are discussed. The various approaches to AM are described, and the current state of clinical translation of AM across these orthopedic clinical scenarios is assessed. Finally, we attempt to distinguish between what AM may offer orthopedic surgery from the hype of what has been promised by AM.