Artificial Metalloenzymes: Recent Developments and Innovations in Bioinorganic Catalysis.

Cellular life is orchestrated by the biochemical components of cells that include nucleic acids, lipids, carbohydrates, proteins, and cofactors such as metabolites and metals, all of which coalesce and function synchronously within the cell. Metalloenzymes allow for such complex chemical processes, as they catalyze a myriad of biochemical reactions both efficiently and selectively, where the metal cofactor provides additional functionality to promote reactivity not readily achieved in their absence. While the past 60 years have yielded considerable insight on how enzymes catalyze these reactions, a need to engineer and develop artificial metalloenzymes has been driven not only by industrial and therapeutic needs, but also by innate human curiosity. The design of miniature enzymes, both rationally and through serendipity, using both organic and inorganic building blocks has been explored by many scientists over the years and significant progress has been made. Herein, recent developments over the past 5 years in areas that have not been recently reviewed are summarized, and prospects for future research in these areas are addressed.

Microfluidic Skin-on-a-Chip Models: Toward Biomimetic Artificial Skin.

The role of skin in the human body is indispensable, serving as a barrier, moderating homeostatic balance, and representing a pronounced endpoint for cosmetics and pharmaceuticals. Despite the extensive achievements of in vitro skin models, they do not recapitulate the complexity of human skin; thus, there remains a dependence on animal models during preclinical drug trials, resulting in expensive drug development with high failure rates. By imparting a fine control over the microenvironment and inducing relevant mechanical cues, skin-on-a-chip (SoC) models have circumvented the limitations of conventional cell studies. Enhanced barrier properties, vascularization, and improved phenotypic differentiation have been achieved by SoC models; however, the successful inclusion of appendages such as hair follicles and sweat glands and pigmentation relevance have yet to be realized. The present Review collates the progress of SoC platforms with a focus on their fabrication and the incorporation of mechanical cues, sensors, and blood vessels.

Validation of diffusion MRI estimates of compartment size and volume fraction in a biomimetic brain phantom using a human MRI scanner with 300 mT/m maximum gradient strength.

Diffusion microstructural imaging techniques have attracted great interest in the last decade due to their ability to quantify axon diameter and volume fraction in healthy and diseased human white matter. The estimates of compartment size and volume fraction continue to be debated, in part due to the lack of a gold standard for validation and quality control. In this work, we validate diffusion MRI estimates of compartment size and volume fraction using a novel textile axon ("taxon") phantom constructed from hollow polypropylene yarns with distinct intra- and extra-taxonal compartments to mimic white matter in the brain. We acquired a comprehensive set of diffusion MRI measurements in the phantom using multiple gradient directions, diffusion times and gradient strengths on a human MRI scanner equipped with maximum gradient strength (Gmax) of 300 mT/m. We obtained estimates of compartment size and restricted volume fraction through a straightforward extension of the AxCaliber/ActiveAx frameworks that enables estimation of mean compartment size in fiber bundles of arbitrary orientation. The voxel-wise taxon diameter estimates of 12.2 ±â€¯0.9 µm were close to the manufactured inner diameter of 11.8 ±â€¯1.2 µm with Gmax = 300 mT/m. The estimated restricted volume fraction demonstrated an expected decrease along the length of the fiber bundles in accordance with the known construction of the phantom. When Gmax was restricted to 80 mT/m, the taxon diameter was overestimated, and the estimates for taxon diameter and packing density showed greater uncertainty compared to data with Gmax = 300 mT/m. In conclusion, the compartment size and volume fraction estimates resulting from diffusion measurements on a human scanner were validated against ground truth in a phantom mimicking human white matter, providing confidence that this method can yield accurate estimates of parameters in simplified but realistic microstructural environments. Our work also demonstrates the importance of a biologically analogous phantom that can be applied to validate a variety of diffusion microstructural imaging methods in human scanners and be used for standardization of diffusion MRI protocols for neuroimaging research.

Laminin peptide YIGSR enhances epidermal development of skin equivalents.

Since the use of animal experimentation is restricted with regard to cosmetic materials, alternative in vitro models such as skin equivalents (SEs) are needed. Laminin is one of the major non-collagenous glycoproteins. The pentapeptide YIGSR (Tyr-Ile-Gly-Ser-Arg) is a functional motif of laminin that binds to the laminin receptor. In the present study, we examined whether YIGSR could improve the reconstruction of SEs. YIGSR has no effects on monolayer cell proliferation of CCD25-Sk fibroblasts or HaCaT keratinocytes. Interestingly, YIGSR decreased TGF-ß1 levels, although it promoted type Ι collagen synthesis in CCD25-Sk cells. In HaCaT cells, YIGSR decreased the expression of involucrin and loricrin, which are differentiation markers. Furthermore, YIGSR increased levels of proliferating cell nuclear antigen (PCNA), p63, and integrin α6, and decreased involucrin in SE models. In addition, two models containing YIGSR (mixed with dermal equivalents or added into media) did not show any differences in expression levels of PCNA, p63, integrin α6, and involucrin. Therefore, YIGSR is a useful agent for reconstruction of SEs, independent of its method of application. These results indicate that YIGSR stimulates epidermal proliferation and basement membrane formation while inhibiting keratinocyte differentiation of SEs. Taken together, these results indicate that YIGSR promotes the reconstruction of SEs, potentially via decreased TGF-ß1 levels and consequent inhibition of epidermal differentiation.

[JUSTIFICATION OF USING EQUIVALENCE OF THE INDICES OF QUALITY, SAFETY, AND EFFICACY IN DEVELOPING BIOANALOGS].

We describe general principles of demonstrating biosimilarity, as well as selecting the biosimilarity margins. Any change in the structure of a biological molecule can modify its functional activity. Therefore, therapeutic equivalence between a biosimilar product and the corresponding reference product cannot be demonstrated using a single criterion. To demonstrate biosimilarity between two medicinal products, their various characteristics have to be evaluated which may, directly or indirectly, justify that clinically significant differences are absent. Insufficient understanding of 6ritical quality attributes brings a risk for the biosimilar product developer. This will either increase the number of non-clinical and clinical tests and trials needed or will result in awareness that the manufacturing process needs to be improved at the late stages of development, after investing significant resources in the development process. At the same time, the specification of the biological medicinal product cannot solely ensure safety and efficacy thereof. Properly characterized and controlled manufacturing process, which ensures consistency in its attributes not adequately controlled in specifications but influencing safety and efficacy profiles and showing their relevance in non-clinical tests and clinical trials, is an additional quality assurance factor. Justification of all development strategy details, including biosimilarity margins, has to be provided each time when the development process is initiated or when proceeding to the next steps. All problems encountered by the developer have to be resolved in close communication with the regulatory authority. In order to increase the quality of investigation and developer's adherence to good practices, clinical trial results should be published in detail.

Enhanced Robot Speech Recognition Using Biomimetic Binaural Sound Source Localization.

Inspired by the behavior of humans talking in noisy environments, we propose an embodied embedded cognition approach to improve automatic speech recognition (ASR) systems for robots in challenging environments, such as with ego noise, using binaural sound source localization (SSL). The approach is verified by measuring the impact of SSL with a humanoid robot head on the performance of an ASR system. More specifically, a robot orients itself toward the angle where the signal-to-noise ratio (SNR) of speech is maximized for one microphone before doing an ASR task. First, a spiking neural network inspired by the midbrain auditory system based on our previous work is applied to calculate the sound signal angle. Then, a feedforward neural network is used to handle high levels of ego noise and reverberation in the signal. Finally, the sound signal is fed into an ASR system. For ASR, we use a system developed by our group and compare its performance with and without the support from SSL. We test our SSL and ASR systems on two humanoid platforms with different structural and material properties. With our approach we halve the sentence error rate with respect to the common downmixing of both channels. Surprisingly, the ASR performance is more than two times better when the angle between the humanoid head and the sound source allows sound waves to be reflected most intensely from the pinna to the ear microphone, rather than when sound waves arrive perpendicularly to the membrane.

Multivalent Binding and Biomimetic Cell Rolling Improves the Sensitivity and Specificity of Circulating Tumor Cell Capture.

Purpose: We aimed to examine the effects of multivalent binding and biomimetic cell rolling on the sensitivity and specificity of circulating tumor cell (CTC) capture. We also investigated the clinical significance of CTCs and their kinetic profiles in patients with cancer undergoing radiotherapy treatment.Experimental Design: Patients with histologically confirmed primary carcinoma undergoing radiotherapy, with or without chemotherapy, were eligible for enrollment. Peripheral blood was collected prospectively at up to five time points, including before radiotherapy, at the first week, mid-point and final week of treatment, as well as 4 to 12 weeks after completion of radiotherapy. CTC capture was accomplished using a nanotechnology-based assay (CapioCyte) functionalized with aEpCAM, aHER-2, and aEGFR.Results: CapioCyte was able to detect CTCs in all 24 cancer patients enrolled. Multivalent binding via poly(amidoamine) dendrimers further improved capture sensitivity. We also showed that cell rolling effect can improve CTC capture specificity (% of captured cells that are CK+/CD45-/DAPI+) up to 38%. Among the 18 patients with sequential CTC measurements, the median CTC decreased from 113 CTCs/mL before radiotherapy to 32 CTCs/mL at completion of radiotherapy (P = 0.001). CTCs declined throughout radiotherapy in patients with complete clinical and/or radiographic response, in contrast with an elevation in CTCs at mid or post-radiotherapy in the two patients with known pathologic residual disease.Conclusions: Our study demonstrated that multivalent binding and cell rolling can improve the sensitivity and specificity of CTC capture compared with multivalent binding alone, allowing reliable monitoring of CTC changes during and after treatment. Clin Cancer Res; 24(11); 2539-47. ©2018 AACR.

Biomimetic bio-inspired biomorph sustainable? An attempt to classify and clarify biology-derived technical developments.

Over the last few decades, the systematic approach of knowledge transfer from biological concept generators to technical applications has received increasing attention, particularly because marketable bio-derived developments are often described as sustainable. The objective of this paper is to rationalize and refine the discussion about bio-derived developments also with respect to sustainability by taking descriptive, normative and emotional aspects into consideration. In the framework of supervised learning, a dataset of 70 biology-derived and technology-derived developments characterised by 9 different attributes together with their respective values and assigned to one of 17 classes was created. On the basis of the dataset a decision tree was generated which can be used as a straightforward classification tool to identify biology-derived and technology-derived developments. The validation of the applied learning procedure achieved an average accuracy of 90.0%. Additional extraordinary qualities of technical applications are generally discussed by means of selected biology-derived and technology-derived examples with reference to normative (contribution to sustainability) and emotional aspects (aesthetics and symbolic character). In the context of a case study from the building sector, all aspects are critically discussed.

Dose Conversion Coefficients Based on Taiwanese Reference Phantoms and Monte Carlo Simulations for Use in External Radiation Protection.

Reference phantoms are widely applied to evaluate the radiation dose for external exposure. However, the frequently used reference phantoms are based on Caucasians. Dose estimation for Asians using a Caucasian phantom can result in significant errors. This study recruited 40 volunteers whose body sizes are close to the average Taiwanese population. Magnetic resonance imaging was performed to obtain the organ volume for construction of the Taiwanese reference man (TRM) and Taiwanese reference woman (TRW). The dose conversion coefficients (DCC) resulting from photo beams in anterior-posterior, posterior-anterior, right-lateral, left-lateral, and isotropic irradiation geometries were estimated. In the anterior-posterior geometry, the mean DCC differences among organs between the TRM and ORNL phantom at 0.1, 1, and 10 MeV were 7.3%, 5.8%, and 5.2%, respectively. For the TRW, the mean differences from the ORNL phantom at the three energies were 10.6%, 7.4%, and 8.3%. The DCCs of the Taiwanese reference phantoms and the ORNL phantom presented similar trends in other geometries. The torso size of the phantom and the mass and geometric location of the organ have a significant influence on the DCC. The Taiwanese reference phantoms can be used to establish dose guidelines and regulations for radiation protection from external exposure.

Nanotechnology and biomimetic methods in therapeutics: molecular scale control with some help from nature.

Nanoscale science and engineering has provided new avenues for engineering materials with macromolecular and even molecular precision. In particular, researchers are beginning to mimic biological systems, achieving molecular scale control via self-assembly and directed assembly techniques. Fabrication and manipulation with macromolecular and molecular precision have led and will lead to the development of novel materials, and these materials will facilitate the fabrication of micro- and nanoscale devices, such as self-regulated micro- and nanoscale drug delivery devices that combine diagnostic and therapeutic actions for instantaneous administration of therapy. As the field of nanoscale science and engineering matures, technologies that will revolutionize the way health care is administered will continue to be developed.

Bottom-up design of biomimetic assemblies.

Nature has evolved the ability to assemble a variety of molecules into functional architectures that can specifically bind cellular ligands. Mimicking this strategy requires the design of a set of multifaceted molecules, where elements that direct assembly were conjugated to biologically specific components. The development of functional molecular building-blocks that assemble to form compartments for therapeutics addresses the desire to have controllable morphologies that interact with biological interfaces at nanometer length scales. The practical application of such 'bottom-up' assemblies requires the ability to predict the type of aggregated structure and to synthesize molecules in a highly controlled fashion. This bottom-up approach results in a molecular platform that mimics biological systems with potential for encapsulating and delivering drug molecules.

Biosimilars: opinion of an expert panel in the Middle East.

BACKGROUND: Several biotechnology-derived drugs are reaching the end of their patent lives. As a result, so-called biosimilar products are in development, and a few have already gained approval in Europe and other countries such as the USA. Biosimilars, unlike generic versions of conventional drugs, are not identical to their reference product, and their production is complex and sensitive to even slight changes in the manufacturing and storage process. Therefore, the registration of these products requires more stringent evaluation than that for conventional generics. METHODS AND SCOPE: A consensus group of experts from the Near and Middle East discussed the currently available guidelines for registration of biosimilars--including those produced by the European Medicines Agency (EMEA)--and their application in this region. To inform this report, a literature search was also conducted on PubMed in January 2008, using the search terms 'biosimilar' and 'follow-on biologic'. This paper provides an overview of the issues in the development and registration of biosimilars, a description of the EMEA guidelines and the recommendations of the consensus group for the registration of biosimilars in the Middle East. FINDINGS: Because of the complex nature of biosimilars and their potential immunogenicity, these products cannot undergo the abbreviated approval process used for generic agents. Instead demonstration of their quality, safety and efficacy, in comparison with their reference biological product, is required. CONCLUSIONS: The consensus group recommended the implementation of the EMEA guidelines as the basis of Regional guidelines for the registration of biosimilars in the Near and Middle East. Registration would, therefore, require demonstration of the robustness of the manufacturing process and quality-control methods, the comparability of pharmacokinetics, pharmacodynamics, efficacy and safety between the biosimilar and reference product and plans for post-marketing surveillance of the long-term risks and immunogenicity of new biosimilars.