Design Optimization of Perfluorinated Liquid-Infused Surfaces for Blood-Contacting Applications

Tethered-liquid perfluorocarbon (TLP) coatings show promise for bloodcontacting medical device applications to reduce blood adhesion and delay thrombosis. However, their fabrication and longevity under external fluid flow is not well characterized. A vapor phase silanization reaction leading to the formation of tethered-perfluorocarbon (TP) layers containing large bumpy aggregates, 300 ± 200 nm thick, on top of an underlying 35 ± 15 nm thick uniform coating is reported. The vapor phase method compares favorably to the well-established liquid phase deposition to reproducibly create slippery coatings on silicon and polystyrene with very low water sliding angles (2° ± 1°), without the need to control humidity conditions. The TP layer retains perfluorinated lubricants up to 20 000 s–1, using a cone-and-plate rheometer, with the higher viscosity lubricant perfluoroperhydrophenanthrene being more resistant to depletion than perfluorodecalin. TLP infused with either of the lubricants effectively reduces adhesion of fibrin from human whole blood relative to TP and control hydrophilic and hydrophobic surfaces. The combination of highly fluorinated TP coatings grafted from the vapor phase to create nanoscale structured surfaces infused with higher viscosity lubricant may be the most suitable combination for clinical applications of liquid-infused surfaces to reduce thrombosis in blood-contacting medical devices under flow

Toxicology of chemically modified graphene-based materials for medical application.

This review article aims to provide an overview of chemically modified graphene, and graphene oxide (GO), and their impact on toxicology when present in biological systems. Graphene is one of the most promising nanomaterials due to unique physicochemical properties including enhanced optical, thermal, and electrically conductive behavior in addition to mechanical strength and high surface-to-volume ratio. Graphene-based nanomaterials have received much attention over the last 5 years in the biomedical field ranging from their use as polymeric conduits for nerve regeneration, carriers for targeted drug delivery and in the treatment of cancer via photo-thermal therapy. Both in vitro and in vivo biological studies of graphene-based nanomaterials help understand their relative toxicity and biocompatibility when used for biomedical applications. Several studies investigating important material properties such as surface charge, concentration, shape, size, structural defects, and chemical functional groups relate to their safety profile and influence cyto- and geno-toxicology. In this review, we highlight the most recent studies of graphene-based nanomaterials and outline their unique properties, which determine their interactions under a range of environmental conditions. The advent of graphene technology has led to many promising new opportunities for future applications in the field of electronics, biotechnology, and nanomedicine to aid in the diagnosis and treatment of a variety of debilitating diseases

Chemotaxis of Drosophila Border Cells is Modulated by Tissue Geometry Through Dispersion of Chemoattractants

Migratory cells respond to graded concentrations of diffusible chemoattractants in vitro, but how complex tissue geometries in vivo impact chemotaxis is poorly understood. To address this, we studied the Drosophila border cells. Live-imaged border cells varied in their chemotactic migration speeds, which correlated positionally with distinct architectures. We then developed a reduced mathematical model to determine how chemoattractant distribution is affected by tissue architecture. Larger extracellular volumes locally dampened the chemoattractant gradient and, when coupled with an agent-based motion of the cluster, reduced cell speeds. This suggests that chemoattractant levels vary by tissue architectures, informing cell migration behaviors locally, which we tested in vivo. Genetically elevating chemoattractant levels slowed migration in specific architectural regions, while mutants with spacious tissue structure rescued defects from high chemoattractant levels, promoting punctual migration. Our results highlight the interplay between tissue geometry and the local distribution of signaling molecules to orchestrate cell migration.We acknowledge funding from NSF DMS #1953423 to B.E.P. and M.S.-G., NSF IOS #2303587 to M.S.-G. and MERCK SHARP and DOHM LLC funding for N.A. For providing commercial fly stocks, we thank the Bloomington Drosophila Stock Center (NIH P40OD018537) and we thank Dr. Trudi Dr. Schupbach for gifting us critical mutant fly lines. We thank FlyBase (release € FB2024_05)56 for all their resourceshttps://www.sciencedirect.com/science/article/pii/S258900422500219

Chemotaxis of Drosophila border cells is modulated by tissue geometry through dispersion of chemoattractants

Summary: Migratory cells respond to graded concentrations of diffusible chemoattractants in vitro, but how complex tissue geometries in vivo impact chemotaxis is poorly understood. To address this, we studied the Drosophila border cells. Live-imaged border cells varied in their chemotactic migration speeds, which correlated positionally with distinct architectures. We then developed a reduced mathematical model to determine how chemoattractant distribution is affected by tissue architecture. Larger extracellular volumes locally dampened the chemoattractant gradient and, when coupled with an agent-based motion of the cluster, reduced cell speeds. This suggests that chemoattractant levels vary by tissue architectures, informing cell migration behaviors locally, which we tested in vivo. Genetically elevating chemoattractant levels slowed migration in specific architectural regions, while mutants with spacious tissue structure rescued defects from high chemoattractant levels, promoting punctual migration. Our results highlight the interplay between tissue geometry and the local distribution of signaling molecules to orchestrate cell migration

A Flexible Joint Longitudinal-Survival Modeling Framework for Incorporating Multiple Longitudinal Biomarkers

We are interested in survival analysis of hemodialysis patients for whom several biomarkers are recorded over time. Motivated by this challenging problem, we propose a general framework for multivariate joint longitudinal-survival modeling that can be used to examine the association between several longitudinally recorded covariates and a time-to-event endpoint. Our method allows for simultaneous modeling of longitudinal covariates by taking their correlation into account. This leads to a more efficient method for modeling their trajectories over time, and hence, it can better capture their relationship to the survival outcomes

Quantification of Long Head of the Biceps Tendon Motion After Loop ‘N’ Tack Suprapectoral Biceps Tenodesis

Objectives: Lesions of the long head of the biceps are one of the most frequent causes of shoulder pain, and they can be successfully treated with biceps tenotomy or tenodesis. The advantage of a biceps tenodesis is avoiding the potential development of a cosmetic deformity (“Popeye sign”) or cramping muscle pain that can remain after tenotomy. Proponents of a subpectoral tenodesis believe that “groove pain” may remain a problem after suprapectoral tenodesis due to persistent motion of the biceps tendon within the bicipital groove. The objective of this study was to evaluate the motion of the biceps tendon within the bicipital groove before and after a suprapectoral tenodesis performed using the Loop ‘N’ Tack technique. Our hypothesis was that there would be minimal to no motion of the biceps tendon within the bicipital groove after the tenodesis. Methods: Six fresh-frozen cadaveric arms were obtained and dissected to expose the long head of biceps tendon and the bicipital groove from the transverse humeral ligament to the pectoralis major insertion. The scapula and ulna were affixed with inclinometers to measure motion in multiple planes. The biceps tendon and bicipital groove were marked with fiducials, which were tracked by two cameras focused on this region. The shoulder and elbow were taken through a full range of motion including scapular abduction, forward flexion, extension, internal rotation, and external rotation and elbow flexion and extension with a supinated, neutral, or pronated forearm. The translation of the biceps tendon was quantified as a function of scapular or forearm motion in each plane. A suprapectoral biceps tenodesis was then performed using the Loop ‘N’ Tack technique. The scapula and forearm were taken through the same motions, and the translation of the biceps tendon was quantified. A paired t-test was performed for each motion to determine if maximum biceps tendon translation in the bicipital groove was a function of tendon condition (native vs post-tenodesis). Results: There was minimal translation of the biceps tendon during elbow flexion and extension, both before and after tenodesis. There was significant translation of the biceps tendon in all planes of scapular motion in the native state, and the largest amount of translation was 20.73mm +/- 8.21mm during shoulder flexion and extension (Table 1). The translation of the biceps tendon after tenodesis was significantly reduced in every plane of scapular motion compared to the native state (p = 0.01 or p &lt; 0.01 in all planes of motion). The largest amount of translation in any plane after tenodesis was 1.57mm +/- 0.98mm, which occured during shoulder flexion and extension (Table 1). Conclusion: In the native state, the translation of the biceps tendon within the bicipital groove ranges from 5.14mm - 20.73mm with scapular motion. There is statistically significant reduction in translation of the biceps tendon in all planes of scapular motion after the Loop ‘N’ Tack tenodesis (Figure 1), with a maximum translation of only 1.57mm. These data suggest that motion of the biceps tendon within the bicipital groove is essentially eliminated and should not be a cause of persistent pain. The Loop ‘N’ Tack biceps tenodesis is a simple, all-arthroscopic technique for patients with proximal biceps pathology. It is a viable alternative to subpectoral tenodesis, essentially eliminating all motion of the biceps tendon within the bicipital groove, and it should not lead to persistent “groove pain”. [Table: see text] </jats:sec