Alterations in gut microbiome composition have an emerging role in health and disease including brain function and behavior. Short chain fatty acids (SCFA) like propionic (PPA), and butyric acid (BA), which are present in diet and are fermentation products of many gastrointestinal bacteria, are showing increasing importance in host health, but also may be environmental contributors in neurodevelopmental disorders including autism spectrum disorders (ASD). Further to this we have shown SCFA administration to rodents over a variety of routes (intracerebroventricular, subcutaneous, intraperitoneal) or developmental time periods can elicit behavioral, electrophysiological, neuropathological and biochemical effects consistent with findings in ASD patients. SCFA are capable of altering host gene expression, partly due to their histone deacetylase inhibitor activity. We have previously shown BA can regulate tyrosine hydroxylase (TH) mRNA levels in a PC12 cell model. Since monoamine concentration is known to be elevated in the brain and blood of ASD patients and in many ASD animal models, we hypothesized that SCFA may directly influence brain monoaminergic pathways. When PC12 cells were transiently transfected with plasmids having a luciferase reporter gene under the control of the TH promoter, PPA was found to induce reporter gene activity over a wide concentration range. CREB transcription factor(s) was necessary for the transcriptional activation of TH gene by PPA. At lower concentrations PPA also caused accumulation of TH mRNA and protein, indicative of increased cell capacity to produce catecholamines. PPA and BA induced broad alterations in gene expression including neurotransmitter systems, neuronal cell adhesion molecules, inflammation, oxidative stress, lipid metabolism and mitochondrial function, all of which have been implicated in ASD. In conclusion, our data are consistent with a molecular mechanism through which gut related environmental signals such as increased levels of SCFA's can epigenetically modulate cell function further supporting their role as environmental contributors to ASD.

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The internal fixation of a fractured bone is generally achieved with bone screws during most orthopedic surgeries. Biodegradable screws have not received as much attention as they deserve. Biodegradable screws reduce the stress‐shielding effect, screw failure, complex, painful revision surgery for screw extraction. The vital focus of the present research is to fabricate cortical bone screws using polylactic acid (PLA) by fused deposition modeling technology. The PLA cortical screws were manufactured with different infill patterns (triangular, honeycomb, grid, and concentric), keeping other parameters constant using three‐dimensional printing. The mechanical behavior and fracture mechanism of different patterned cortical screws were observed based on compression testing and tensile testing of screws. Scanning electron microscopy (SEM) observed the surface topographical features, fracture behavior, and microstructure characterization of different patterned polymeric cortical screws were observed using SEM. Based on the SEM micrographs, mechanical characterization of compression and tensile testing shows the stress, fractures and fatigue cracks propagation at the bone screw interfaces by fractures copy. Moreover, it was observed that the fracture mechanism of ductile to brittle fracture was observed with variation in the infill pattern of the bone screw. The outcomes revealed that the cortical screw with honeycomb infill pattern has the highest compressive and tensile strength than other infill patterns. Honeycomb structured cortical screws have approximately 17% higher compressive strength and 30% higher tensile strength than the triangular patterned cortical screw due to higher bonding surface area at the intercalated layers.

Drilling of bone is required to repair and align the bone when faced with a major fracture. The screw and implant are used for fixing the fractured part of the bone. The failure of osteosynthesis is due to strength between the bone and screw, which majorly depends upon the pull-out strength of the cortical screw. Pull-out strength is the force required to pull a screw out of its foundation from the bone. After the fixation of cortical screws, the major forces acting on the fixation of the screw and the implanted device in the bone. Therefore, it needs to make sure that the screw must fit into the place and grasp the bone within the drilled hole. The intended focus of this research is to see the effect of surface roughness induced during the bone drilling operation on pull-out strength with rotary ultrasonic bone drilling (RUBD) and standard conventional bone drilling (CBD). This is observed that a drilled hole in a bone exhibits greater pull-out strength with more surface roughness because more anchoring is provided by the roughened surface. Also, the apatite formation of the bone shows the biocompatible nature of porcine bone in the simulated body fluid (SBF) solution. RUBD using different grit size in a hollow drilling burr resulted that coarse abrasive have maximum effort for higher surface roughness. Furthermore, the higher surface texture provides a better bone growth rate as it provides peaks for branching and nucleation when preserved in SBF. RUBD provides precise cutting to the bone as compared to CBD. On the 28th day of the bone-screw samples to be immersed in SBF results 42.82% higher pull-out strength of screw in case of RUBD as compared to CBD.

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Purpose The complications caused by metallic orthopaedic bone screws like stress-shielding effect, screw loosening, screw migration, higher density difference, painful reoperation and revision surgery for screw extraction can be overcome with the bioabsorbable bone screws. This study aims to use additive manufacturing (AM) technology to fabricate orthopaedic biodegradable cortical screws to reduce the bone-screw-related-complications. Design/methodology/approach The fused filament fabrication technology (FFFT)-based AM technique is used to fabricate orthopaedic cortical screws. The influence of various process parameters like infill pattern, infill percentage, layer height, wall thickness and different biological solutions were observed on the compressive strength and degradation behaviour of cortical screws. Findings The porous lattice structures in cortical screws using the rapid prototyping technique were found to be better as porous screws can enhance bone growth and accelerate the osseointegration process with sufficient mechanical strength. The compressive strength and degradation rate of the screw is highly dependent on process parameters used during the fabrication of the screw. The compressive strength of screw is inversely proportional to the degradation rate of the cortical screw. Research limitations/implications The present study is focused on cortical screws. Further different orthopaedic screws can be modified with the use of different rapid prototyping techniques. Originality/value The use of rapid prototyping techniques for patient-specific bone screw designs is scantly reported. This study uses FFFT-based AM technique to fabricate various infill patterns and porosity of cortical screws to enhance the design of orthopaedic cortical screws.

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COVID-19 has been spread in more than 220 countries and caused global health concerns. The supply chain disruptions have abruptly affected due to the second wave of COVID-19 in various countries and caused unavailability and shortage of medical devices and personal protective equipment for frontline healthcare workers. Three-dimensional (3D) printing has proven to be a boon and revolutionized technology to supply medical devices and tackle the situation caused by the COVID-19 pandemic. The diverse designs were produced and are currently used in hospitals by patients and frontline healthcare doctors. This review summarises the application of 3D printing during COVID-19. It collects the comprehensive information of recently designed and fabricated protective equipment like nasopharyngeal swabs, valves, face shields, facemasks and many more medical devices. The drawbacks and future challenges of 3D printed medical devices and protective equipment is discussed.