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1. A Novel pressure regulating brain imaging implant for ultra large field of view microscopic imaging in primates

   Caballero, Olivya; Chanovas, Jordi; Ledo, Manuel; Nandy, Anirvan; Yazdah-Shahmorad, Azadeh; Callaway, Edward; Seidemann, E.; Reynolds, John; Avery, Michael; Li, Peichao; et al (January 2021, Society for Neuroscience 2021)

   Several problems challenge mesoscopic imaging in the brain: 1) Difficulty with positioning high-NA objectives near the brain; 2) Creating a flat imaging window against the surface of the brain; 3) Adjusting the imaging window in the face of changes in swelling and pressure in the brain; 4) Preventing growth of dura and biofilms that obscure the imaging window; 5) Follow-on MRI imaging of the animal post-implantation. We propose here an ultra-large window radiolucent implant to address these issues. Our approach provides a 2 cm diameter window for non-human primates (NHPs) that regulates pressure and employs a stable, strong, and thin design. The system is mechanically modeled and stress-tested to achieve access to the brain by large objectives, with design features that allow for manual repositioning of the imaging lens. To optimize the distance between the objective and the brain, we prioritize a thin implant design. A strong radiolucent implant is created using PEEK plastic, a strong, thermoresistant and biostable material. We heighten strength of the chamber’s attachment to the skull by using titanium screws that are normal to the surface of the bone at each point. The implant design has several parts and contemplates a potential method to maintain pressure on the brain. This method uses an engineered silicone mount to maintain even pressure of the imaging window on the brain’s surface, despite brain motion. The mechanical properties of the silicone are manipulated to closely resemble that of brain tissue to be more biomimetic and act as a cushion for motion. This method also allows for themanual repositioning of the cover slip to create a flat imaging window. Lastly, our approach prevents dural growth by blocking the migration of migratory biofilm-forming cells; we hypothesize that use of dynamic pressure maintenance on the brain is key to this method’s success. We are also investigating methods to elongate the longevity of the implant and imaging site, such as silver sputtering on implants and blue light therapy. These methods have produced an ultra-large field of view with 2P image results in <60,000 neurons. As such the chambers are expected to enhance recording window longevity and may prove to be a critical advance in NHP and human brain imaging. 

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2. Liposomes as Imaging Agents of Inflammation and Oxidative Stress in Bone Implants

   https://doi.org/10.3390/cimb47050295  

   Danila, Delia; Pardo, Patricia S; Misra, R_Devesh Kumar; Boriek, Aladin M (May 2025, Current issues in molecular biology)

   Liposomes are tiny, spherical vesicles made from cholesterol and natural phospholipids that are promising imaging agents for detecting medical complications. They can carry fluorescent markers or other imaging agents, making them effective for medical imaging. Furthermore, liposomes can target specific cells involved in inflammation, such as macrophages, and accumulate at inflammation sites when injected. Additionally, liposomes can be designed to respond to oxidative stress, which is often associated with bone implant complications. By detecting areas of stress, liposomes provide valuable information about implant health. However, challenges such as rapid clearance from the body, precise targeting, immune reactions, and high production costs must be addressed. Research is ongoing to improve the design and functionality of liposomes. They can potentially monitor bone implants as non-invasive imaging agents, enabling early detection of complications and timely interventions. This approach can enhance patient outcomes and extend the longevity of implants, making it a promising strategy for better patient care and implant success. 

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3. Silicone implant surface roughness, friction, and wear

   https://doi.org/10.1088/2051-672X/ac9f5a  

   Atkins, Dixon J; Chau, Allison L; Rosas, Jonah M; Chen, Yen-Tsung; Chan, Samantha T; Manuel Urueña, Juan; Pitenis, Angela A (March 2023, Surface Topography: Metrology and Properties)

   Abstract Some textured silicone breast implants with high average surface roughness (‘macrotextured’) have been associated with a rare cancer of the immune system, Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL). Silicone elastomer wear debris may lead to chronic inflammation, a key step in the development of this cancer. Here, we model the generation and release of silicone wear debris in the case of a folded implant-implant (‘shell-shell’) sliding interface for three different types of implants, characterized by their surface roughness. The ‘smooth’ implant shell with the lowest average surface roughness tested (R a = 2.7 ± 0.6 μ m) resulted in average friction coefficients of μ avg = 0.46 ± 0.11 across 1,000 mm of sliding distance and generated 1,304 particles with an average particle diameter of D avg = 8.3 ± 13.1 μ m. The ‘microtextured’ implant shell (R a = 32 ± 7.0 μ m) exhibited μ avg = 1.20 ± 0.10 and generated 2,730 particles with D avg = 4.7 ± 9.1 μ m. The ‘macrotextured’ implant shell (R a = 80 ± 10 μ m) exhibited the highest friction coefficients, μ avg = 2.82 ± 0.15 and the greatest number of wear debris particles, 11,699, with an average particle size of D avg = 5.3 ± 3.3 μ m. Our data may provide guidance for the design of silicone breast implants with lower surface roughness, lower friction, and smaller quantities of wear debris. 

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4. In vitro models of soft tissue damage by implant-associated frictional shear stresses

   https://doi.org/10.1177/13506501221132897  

   Rosas, Jonah M.; Atkins, Dixon J.; Chau, Allison L.; Chen, Yen-Tsung; Bae, Rachel; Cavanaugh, Megan K.; Espinosa Lima, Ricardo I.; Bordeos, Andrew; Bryant, Michael G.; Pitenis, Angela A. (May 2023, Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology)

   Silicone elastomer medical implants are ubiquitous in medicine, particularly for breast augmentation. However, when these devices are placed within the body, disruption of the natural biological interfaces occurs, which significantly changes the native energy-dissipation mechanisms of living systems. These new interfaces can introduce non-physiological contact pressures and tribological conditions that provoke inflammation and soft tissue damage. Despite their significance, the biotribological properties of implant-tissue and implant-extracellular matrix (ECM) interfaces remain poorly understood. Here, we developed an in vitro model of soft tissue damage using a custom-built in situ biotribometer mounted onto a confocal microscope. Sections of commercially-available silicone breast implants with distinct and clinically relevant surface roughness ([Formula: see text]m, [Formula: see text]m, and [Formula: see text]m) were mounted to spherically-capped hydrogel probes and slid against collagen-coated hydrogel surfaces as well as healthy breast epithelial (MCF10A) cell monolayers to model implant-ECM and implant-tissue interfaces. In contrast to the “smooth” silicone implants ([Formula: see text]m), we demonstrate that the “microtextured” silicone implant ([Formula: see text]m) induced higher frictional shear stress ([Formula: see text]  Pa), which led to greater collagen removal and cell rupture/delamination. Our studies may provide insights into post-implantation tribological interactions between silicone breast implants and soft tissues. 

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5. Effect of Prolonged Pressure on Hemodynamics of Sacral Tissues Assessed by Diffuse Optical Imaging: A Pilot Study

   https://doi.org/10.1007/978-3-030-48238-1_53  

   Day, B Pollonini (May 2021, Advances in experimental medicine and biology)

   null (Ed.)

   Pressure injuries (PIs) are wounds resulting from prolonged pressure exerting on the skin and underlying tissues over bony prominences (e.g., lower back, heels, shoulders) in bed-bound patients and wheelchair users. Minimizing pressure has long been considered the most effective preventative method, and current guidelines require visual skin inspection and repositioning every two hours. However, these strategies are often applied deficiently and do not adequately prevent PIs from becoming penetrating wounds. Recent studies attribute the development of PIs to cell deformation, inflammatory, and ischemic damages that cumulatively propagate from the microscale (death of few cells) to the macroscale (tissue necrosis) within one to several hours. Although the nature of the PI pathogenesis is complex and multifactorial, measuring tissue alterations in real-time may elucidate the origination mechanism and ultimately allow detecting PIs at the earliest stage. In this pilot study, we evaluated the ability of diffuse optical imaging (DOI) to assess hemodynamic changes resulting from prolonged pressure on the sacral tissues in five healthy volunteers laying immobile in a supine position for 2 hours. A thin, body-conforming optical imaging probe encompassing 256 optodes arranged in a regularly spaced grid over a 160 × 160 mm area was used to construct DOI volumetric images representing changes of oxyhemoglobin (HbO2) and deoxyhemoglobin (HHb) concentration from a zeroed baseline. After 2 hours of continuous body weight pressure, hemodynamic images in all subjects were substantially dissimilar from their individual baseline. We also found that hemodynamic similarity computed pairwise across subjects exhibited a high value and limited variability around the mean, thus denoting a consistent level of image similarity across subjects. These preliminary results indicate that prolonged pressure causes distinctive hemodynamic patterns that can be effectively investigated with DOI and that monitoring functional changes over time holds potential for clarifying the development mechanisms of PIs. 

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