ABSTRACT
Within the Ear, Nose, and Throat (ENT) medical space, a relatively small fraction of patients follow through with elective surgeries to fix ailments such as a deviated septum or occluded sinus passage. Patient understanding of their diagnosis and treatment plan is integral to compliance, which ultimately yields improved medical outcomes and better quality of life. Here we report the usage of advanced, polyjet 3D printing methods to develop a multimaterial replica of human nasal sinus anatomy, derived from clinical X-ray computed tomography (CT) data, to be used as an educational aid during physician consultation. The final patient education model was developed over several iterations to optimize material properties, anatomical accuracy and overall display. A two-arm, single-center, randomized, prospective study was then performed in which 50 ENT surgical candidates (and an associated control group, n = 50) were given an explanation of their anatomy, disease state, and treatment options using the education model as an aid. Statistically significant improvements in patient ratings of their physician's explanation of their treatment options (p = 0.020), self-rated anatomical understanding (p = 0.043), self-rated understanding of disease state (p = 0.016), and effectiveness of the visualization (p = 0.007) were noted from the population that viewed the 3D education model, indicating it is an effective tool which ENT surgeons may use to educate and interact with patients.
ABSTRACT
Radiopacity is a critical property of materials that are used for a range of radiological applications, including the development of phantom devices that emulate the radiodensity of native tissues and the production of protective equipment for personnel handling radioactive materials. Three-dimensional (3D) printing is a fabrication platform that is well suited to creating complex anatomical replicas or custom labware to accomplish these radiological purposes. We created and tested multiple ABS (Acrylonitrile butadiene styrene) filaments infused with varied concentrations of bismuth (1.2-2.7 g/cm³), a radiopaque metal that is compatible with plastic infusion, to address the poor gamma radiation attenuation of many mainstream 3D printing materials. X-ray computed tomography (CT) experiments of these filaments indicated that a density of 1.2 g/cm³ of bismuth-infused ABS emulates bone radiopacity during X-ray CT imaging on preclinical and clinical scanners. ABS-bismuth filaments along with ABS were 3D printed to create an embedded human nasocranial anatomical phantom that mimicked radiological properties of native bone and soft tissue. Increasing the bismuth content in the filaments to 2.7 g/cm³ created a stable material that could attenuate 50% of 99mTechnetium gamma emission when printed with a 2.0 mm wall thickness. A shielded test tube rack was printed to attenuate source radiation as a protective measure for lab personnel. We demonstrated the utility of novel filaments to serve multiple radiological purposes, including the creation of anthropomorphic phantoms and safety labware, by tuning the level of radiation attenuation through material customization.
Subject(s)
Phantoms, Imaging , Bismuth , Humans , Printing, Three-Dimensional , Radiography , Tomography, X-Ray ComputedABSTRACT
Advances in three-dimensional (3D) printing allow for digital files to be turned into a "printed" physical product. For example, complex anatomical models derived from clinical or pre-clinical X-ray computed tomography (CT) data of patients or research specimens can be constructed using various printable materials. Although 3D printing has the potential to advance learning, many academic programs have been slow to adopt its use in the classroom despite increased availability of the equipment and digital databases already established for educational use. Herein, a protocol is reported for the production of enlarged bone core and accurate representation of human sinus passages in a 3D printed format using entirely consumer-grade printers and a combination of free-software platforms. The comparative resolutions of three surface rendering programs were also determined using the sinuses, a human body, and a human wrist data files to compare the abilities of different software available for surface map generation of biomedical data. Data shows that 3D Slicer provided highest compatibility and surface resolution for anatomical 3D printing. Generated surface maps were then 3D printed via fused deposition modeling (FDM printing). In conclusion, a methodological approach that explains the production of anatomical models using entirely consumer-grade, fused deposition modeling machines, and a combination of free software platforms is presented in this report. The methods outlined will facilitate the incorporation of 3D printed anatomical models in the classroom. Anat Sci Educ 10: 383-391. © 2017 American Association of Anatomists.
Subject(s)
Anatomy/education , Education, Medical, Undergraduate/methods , Models, Anatomic , Printing, Three-Dimensional , Software , Datasets as Topic , Humans , Imaging, Three-Dimensional , Learning , Students, Medical/psychology , Tomography, X-Ray ComputedABSTRACT
Anfinsen's principle asserts that all information required to specify the structure of a protein is encoded in its amino acid sequence. However, during protein synthesis by the ribosome, the N-terminus of the nascent chain can begin to fold before the C-terminus is available. We tested whether this cotranslational folding can alter the folded structure of an encoded protein in vivo, versus the structure formed when refolded in vitro. We designed a fluorescent protein consisting of three half-domains, where the N- and C-terminal half-domains compete with each other to interact with the central half-domain. The outcome of this competition determines the fluorescence properties of the resulting folded structure. Upon refolding after chemical denaturation, this protein produced equimolar amounts of the N- and C-terminal folded structures, respectively. In contrast, translation in Escherichia coli resulted in a 2-fold enhancement in the formation of the N-terminal folded structure. Rare synonymous codon substitutions at the 5' end of the C-terminal half-domain further increased selection for the N-terminal folded structure. These results demonstrate that the rate at which a nascent protein emerges from the ribosome can specify the folded structure of a protein.
Subject(s)
Codon/genetics , Protein Engineering/methods , Proteins/genetics , Amino Acid Sequence , Escherichia coli/genetics , Proteins/chemistryABSTRACT
Stroke is the third leading cause of death among Americans 65 years of age or older(1). The quality of life for patients who suffer from a stroke fails to return to normal in a large majority of patients(2), which is mainly due to current lack of clinical treatment for acute stroke. This necessitates understanding the physiological effects of cerebral ischemia on brain tissue over time and is a major area of active research. Towards this end, experimental progress has been made using rats as a preclinical model for stroke, particularly, using non-invasive methods such as (18)F-fluorodeoxyglucose (FDG) coupled with Positron Emission Tomography (PET) imaging(3,10,17). Here we present a strategy for inducing cerebral ischemia in rats by middle cerebral artery occlusion (MCAO) that mimics focal cerebral ischemia in humans, and imaging its effects over 24 hr using FDG-PET coupled with X-ray computed tomography (CT) with an Albira PET-CT instrument. A VOI template atlas was subsequently fused to the cerebral rat data to enable a unbiased analysis of the brain and its sub-regions(4). In addition, a method for 3D visualization of the FDG-PET-CT time course is presented. In summary, we present a detailed protocol for initiating, quantifying, and visualizing an induced ischemic stroke event in a living Sprague-Dawley rat in three dimensions using FDG-PET.
Subject(s)
Brain Ischemia/diagnostic imaging , Fluorodeoxyglucose F18 , Positron-Emission Tomography/methods , Radiopharmaceuticals , Animals , Fluorodeoxyglucose F18/administration & dosage , Male , Radiopharmaceuticals/administration & dosage , Rats , Rats, Sprague-DawleyABSTRACT
Newly synthesized proteins must form their native structures in the crowded environment of the cell, while avoiding non-native conformations that can lead to aggregation. Yet, remarkably little is known about the progressive folding of polypeptide chains during chain synthesis by the ribosome or of the influence of this folding environment on productive folding in vivo. P22 tailspike is a homotrimeric protein that is prone to aggregation via misfolding of its central beta-helix domain in vitro. We have produced stalled ribosome:tailspike nascent chain complexes of four fixed lengths in vivo, in order to assess cotranslational folding of newly synthesized tailspike chains as a function of chain length. Partially synthesized, ribosome-bound nascent tailspike chains populate stable conformations with some native-state structural features even prior to the appearance of the entire beta-helix domain, regardless of the presence of the chaperone trigger factor, yet these conformations are distinct from the conformations of released, refolded tailspike truncations. These results suggest that organization of the aggregation-prone beta-helix domain occurs cotranslationally, prior to chain release, to a conformation that is distinct from the accessible energy minimum conformation for the truncated free chain in solution.
Subject(s)
Bacteriophage P22/chemistry , Protein Biosynthesis , Protein Folding , Protein Structure, Secondary , Viral Tail Proteins/chemistry , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/genetics , Antibodies, Monoclonal/metabolism , Glycoside Hydrolases , Models, Molecular , Molecular Chaperones/metabolism , Peptide Fragments/chemistry , Peptide Fragments/genetics , Peptide Fragments/metabolism , Protein Structure, Tertiary , Ribosomes/metabolism , Viral Tail Proteins/genetics , Viral Tail Proteins/metabolismABSTRACT
Glyoxalase 2 is a beta-lactamase fold-containing enzyme that appears to be involved with cellular chemical detoxification. Although the cytoplasmic isozyme has been characterized from several organisms, essentially nothing is known about the mitochondrial proteins. As a first step in understanding the structure and function of mitochondrial glyoxalase 2 enzymes, a mitochondrial isozyme (GLX2-5) from Arabidopsis thaliana was cloned, overexpressed, purified, and characterized using metal analyses, EPR and (1)H NMR spectroscopies, and x-ray crystallography. The recombinant enzyme was shown to bind 1.04 +/- 0.15 eq of iron and 1.31 +/- 0.05 eq of Zn(II) and to exhibit k(cat) and K(m) values of 129 +/- 10 s(-1) and 391 +/- 48 microm, respectively, when using S-d-lactoylglutathione as the substrate. EPR spectra revealed that recombinant GLX2-5 contains multiple metal centers, including a predominant Fe(III)Z-n(II) center and an anti-ferromagnetically coupled Fe(III)Fe(II) center. Unlike cytosolic glyoxalase 2 from A. thaliana, GLX2-5 does not appear to specifically bind manganese. (1)H NMR spectra revealed the presence of at least eight paramagnetically shifted resonances that arise from protons in close proximity to a Fe(III)Fe(II) center. Five of these resonances arose from solvent-exchangeable protons, and four of these have been assigned to NH protons on metal-bound histidines. A 1.74-A resolution crystal structure of the enzyme revealed that although GLX2-5 shares a number of structural features with human GLX2, several important differences exist. These data demonstrate that mitochondrial glyoxalase 2 can accommodate a number of different metal centers and that the predominant metal center is Fe(III)Zn(II).