Annals of Biomedical Engineering最新文献

Purpose

In nasal reconstruction, cartilage struts are used to create the structural foundation of the nose. These struts, carved from autologous or allogeneic grafts of costal cartilage, are often limited by availability, warping, or resorption. This study aimed to investigate the mechanical and biochemical outcomes of applying dynamic bidirectional bending to tissue-engineered constructs, hypothesizing that such stimulation would improve matrix synthesis and mechanical properties.

Methods

Chondrocyte-seeded agarose struts were subjected to two weeks of dynamic bidirectional four-point bending at peak-to-peak strain amplitudes of 0, 2.5, 5, and 7.5%, for 1200 cycles at 1 Hz starting after a two-week pre-culture. Constructs were analyzed for DNA, proteoglycan, and collagen content, and evaluated via histology, polarized light microscopy, and four-point bending tests. Outcomes were compared to unstimulated controls, unidirectionally stimulated constructs, and native septal cartilage.

Results

Bidirectional bending at a 2.5% strain amplitude increased collagen content by 74% and bending modulus by 72% relative to controls. Under 5% strain amplitudes, proteoglycan accumulation peaked with a 51% increase. Constructs stimulated unidirectionally showed reduced matrix deposition. Histological analysis demonstrated enhanced ECM deposition with region-specific proteoglycan and collagen distribution, partially resembling zonal patterns in native cartilage, although engineered constructs remained mechanically inferior to native septal cartilage.

Conclusion

Dynamic bidirectional bending enhances the biochemical and mechanical properties of tissue-engineered constructs. Lower strain amplitudes were most effective, supporting its consideration in developing mechanically robust grafts for nasal reconstruction. Further optimization of loading protocols and culture duration is needed to bridge the gap with native tissue performance.

Purpose

Traumatic brain injury remains a major health concern among civilians and military personnel, with intracranial cavitation hypothesized as a damage mechanism during blunt impacts.

Methods

This study examines cavitation bubble activity in simplified polyacrylamide human head models, focusing on different anatomical regions and imaging modalities. A drop tower setup with high-speed acoustic and optical imaging was used to characterize the onset, expansion, and collapse of bubbles and assess the impact orientation’s effects.

Results

Acoustic plane wave imaging and passive cavitation detection captured emissions linked to bubble dynamics. Although plane wave imaging was affected by reflections, it detected bubble growth effectively. In contrast, passive cavitation detection showed greater sensitivity during collapse, with broadband spectral responses. Signal processing extracted relevant spectral features from both modalities, regardless of pre-existing bubble nuclei. Cavitation behavior varied across models, with impact angle influencing both timing and persistence, suggesting orientation affects injury mechanisms. When the head model was impacted at a 90° angle and observed along the central sulcus, cavitation onset occurred earliest with the strongest shockwave reflections, likely due to changes in wave travel distance between the coup and contrecoup sites. Head models with artificial dampeners showed that the scalp and dura mater layers reduced cavitation intensity, though cavitation remained detectable.

Conclusion

This work supports the feasibility of acoustically detecting impact-induced cavitation as a standalone tool, informing strategies for transcranial monitoring and protective gear design in blunt trauma scenarios.

Aortic dissection (AD) is a catastrophic vascular pathology caused by delamination of the vascular wall and the formation of a false lumen. False lumen haemodynamics is a key determinant of aneurysmal growth, rupture, and thrombosis. Quantifying the haemodynamics in the false lumen can provide markers to predict these events and stratify patient risk. While such metrics can be extracted from numerical simulations or imaging modalities such as 4D flow MR, high-resolution experimental data are needed to validate them. The present study provides an in vitro characterization of the flow inside the false lumen of a type B aortic dissection using a patient-specific flexible phantom and Particle Image Velocimetry. A mock circulatory loop imposing patient-specific flow waveforms at the inlet and outlets of the aortic phantom and a refractive index matching blood analog were employed. Time-resolved measurements of the velocity field in four selected planes of the false lumen were acquired. Compared against our previous work on the same dissection assuming rigid walls, the results demonstrate the impact of wall compliance on the flow in the false lumen. They revealed the generation of a jet during the systolic phase that enters the false lumen through the primary tear and impinging on the opposite wall with high velocity, generating a strong rotational flow therein. During the diastolic phase, a reversal of the flow was observed generating multiple vortical structures both inside the true and false lumen. Haemodynamic markers such as false lumen ejection fraction were calculated and compared with clinical measurements. The results provide an insight on AD haemodynamics and highlight the potential of this in vitro method as a validation tool for simulations, as well as to physically test interventions in vitro.

Purpose

This study aims to evaluate an adapted needs‐finding process, termed “Caredesign,” which focuses on identifying service delivery and administrative inefficiencies in low‐ and middle‐income countries (LMICs). The research question is whether modifying the traditional Biodesign needs‐finding phase can yield actionable insights for healthcare service innovation in resource‐constrained settings.

Methods

At a public university teaching hospital in Iran, we conducted semi‐structured interviews with 47 healthcare professionals (doctors, nurses, and administrators) to gather perceptions on operational challenges. A total of 354 problem statements were collected and then manually analyzed and categorized into six thematic groups. The process incorporated financial (money cycle) and temporal (time cycle) analyses to assess cost and time inefficiencies. Additionally, a bibliometric analysis using VOSviewer was performed to contextualize our findings within the broader field of healthcare innovation.

Results

Our analysis revealed that 23% of the problem statements pertained to executive management processes, 22% each to healthcare facility workspace management and medical technology, 17% to medical device management, 10% to human resource management, and 6% to data management. These results indicate that, contrary to the traditional focus on device innovation, systemic inefficiencies in service delivery dominate in LMIC healthcare settings.

Conclusion

The Caredesign approach demonstrates potential as a scalable, service-oriented framework that complements the traditional Biodesign process. By addressing operational challenges, it offers a promising pathway for enhancing healthcare innovation in resource-limited environments.

Introduction

Personalized in silico models offer great potential for improving our understanding of atrial arrhythmia mechanisms and for testing therapeutic strategies. However, the level of complexity that can be achieved in these models is often limited by the availability of clinical data. Therefore, evaluating how variations in model detail affect electrophysiological simulation outcomes is essential for evaluating how accurate these models need to be.

Purpose

To evaluate how substrate conditions (electrical remodeling and diffusion) and the inclusion of fiber orientation and ionic heterogeneities provide significant differences in simulation outcomes.

Methods

N = 320 simulations were performed in a realistic 3D model of the human atria considering different conditions: the presence and absence of fiber orientation, regional ionic heterogeneities and different levels of electrical remodeling and electrical diffusion, simulating disease progression. Their arrhythmic behavior was evaluated as the percentage of cases that sustained atrial arrhythmias and the classification of these according to their type as either functional or anatomical.

Results

Fiber orientation and electrical diffusion were the parameters that most strongly influenced the simulation outcomes. Including fiber orientation significantly altered both the incidence (44% vs. 67%, p = 0.02) and type of reentries (31% vs. 57% functional reentries, p = 0.055). In terms of electrical diffusion, reduced conduction velocity led to a significantly higher arrhythmogenicity (83% vs. 33%, p = 0.008) and an increased proportion of functional reentries (59% vs. 29%, p = 0.08). Electrical remodeling and ionic heterogeneities did not provide statistically significant differences. However, ionic heterogeneities proved to play an important role in generating different proarrhythmic patterns.

Conclusion

Fiber orientation and electrical diffusion play a relevant role in personalized simulations, since these parameters produced significant effects in simulation behavior. Therefore, they should be considered for personalized simulations. Electrical remodeling and tissue heterogeneity have a minor impact in terms of arrhythmia inducibility, but they should be considered to evaluate specific mechanisms and/or target regions in personalized simulations.

Purpose

Neonatal jaundice is a common condition that can lead to serious complications if left untreated. Although phototherapy is the standard treatment, existing devices are often costly, energy-intensive and fail to deliver the required intensity or provide uniform irradiance, particularly in low-resource settings. This study aims to design and optimize a low-cost, energy-efficient phototherapy bed that meets clinical requirements for irradiance intensity and spatial uniformity.

Methods

A multi-objective photometric optimization approach was applied to design the phototherapy bed, focusing on balancing irradiance intensity, glare control, and dark spot avoidance. Simulations were performed using a Lambertian emission model to determine the ideal LED configuration. Different LED grid layouts with varying LED spacing were simulated. The optical properties of all materials, including the LEDs, diffuser, bed flat, and mattress, were tested. The device design and assembly are described.

Results

The optimal LED configuration, a hexagonal grid with approximately 9 cm spacing, yielded the best performance. The measurement verification for the Lambertian emission model showed strong agreement with the simulation results. Prototype testing achieved a mean irradiance of 44.78 μW/cm²/nm with a relative standard deviation of 0.36. The diffuser and mattress positively influenced irradiance by improving uniformity, avoiding dark spots, and reducing glare.

Conclusions

This system, with a material cost of approximately $80, offers an affordable and clinically effective solution for neonatal jaundice therapy in low-resource settings. It supports home treatment and promotes mother-infant bonding. The proposed optimization methodology can serve as a design reference for future light-based therapeutic systems.

Graphical Abstract