Unraveling Pre-filled Syringe Needle Clogging: Exploring a Fresh Outlook Through Innovative Techniques

OBJECTIVE

This study aimed to investigate the movement of liquid in the needle region of staked-in-needle pre-filled syringes using neutron imaging and synchrotron X-ray tomography. The objective was to gain insights into the dynamics of liquid presence and understand the factors contributing to needle clogging.

METHODS

Staked-in-needle pre-filled syringes were examined using neutron radiography and synchrotron X-ray phase-contrast computed tomography. Neutron radiography provided a 2D visualization of liquid presence in the needle, while synchrotron X-ray tomography offered high-resolution 3D imaging to study detailed morphological features of the liquid.

RESULTS

Neutron radiography revealed liquid presence in the needle region for as-received samples and after temperature and pressure cycling. Pressure cycling had a more pronounced effect on liquid formation. Synchrotron X-ray tomography confirmed the presence of liquid and revealed various morphologies, including droplets of different sizes, liquid segments blocking sections of the needle, and a thin layer covering the needle wall. Liquid presence was also observed between the steel needle and the glass barrel.

CONCLUSIONS

The combination of neutron imaging and synchrotron X-ray tomography provided valuable insights into the dynamics of liquid movement in staked-in-needle pre-filled syringes. Temperature and pressure cycling were found to contribute to additional liquid formation, with pressure changes playing a significant role. The detailed morphological analysis enhanced the understanding of microstructural arrangements within the needle. This research contributes to addressing the issue of needle clogging and can guide the development of strategies to improve pre-filled syringe performance.

Multi-resolution X-ray phase-contrast and dark-field tomography of human cerebellum with near-field speckles

In this study, we use synchrotron-based multi-modal X-ray tomography to examine human cerebellar tissue in three dimensions at two levels of spatial resolution (2.3 µm and 11.9 µm). We show that speckle-based imaging (SBI) produces results that are comparable to propagation-based imaging (PBI), a well-established phase-sensitive imaging method. The different SBI signals provide complementary information, which improves tissue differentiation. In particular, the dark-field signal aids in distinguishing tissues with similar average electron density but different microstructural variations. The setup's high resolution and the imaging technique's excellent phase sensitivity enabled the identification of different cellular layers and additionally, different cell types within these layers. We also correlated this high-resolution phase-contrast information with measured dark-field signal levels. These findings demonstrate the viability of SBI and the potential benefit of the dark-field modality for virtual histology of brain tissue.

Unraveling the role of TGFβ signaling in thoracic aortic aneurysm and dissection using Fbn1 mutant mouse models

Although abnormal TGFβ signaling is observed in several heritable forms of thoracic aortic aneurysms and dissections including Marfan syndrome, its precise role in aortic disease progression is still disputed. Using a mouse genetic approach and quantitative isobaric labeling proteomics, we sought to elucidate the role of TGFβ signaling in three Fbn1 mutant mouse models representing a range of aortic disease from microdissection (without aneurysm) to aneurysm (without rupture) to aneurysm and rupture. Results indicated that reduced TGFβ signaling and increased mast cell proteases were associated with microdissection. In contrast, increased abundance of extracellular matrix proteins, which could be reporters for positive TGFβ signaling, were associated with aneurysm. Marked reductions in collagens and fibrillins, and increased TGFβ signaling, were associated with aortic rupture. Our data indicate that TGFβ signaling performs context-dependent roles in the pathogenesis of thoracic aortic disease.

Fluid-Structure Interaction Modeling of the Aortic Hemodynamics in Adult Zebrafish: a Pilot Study based on Synchrotron X-Ray Tomography

OBJECTIVE

The zebrafish is increasingly used as a small animal model for cardiovascular disease, including vascular disorders. Nevertheless, a comprehensive biomechanical understanding of the zebrafish cardiovascular circulation is still lacking and possibilities for phenotyping the zebrafish heart and vasculature at adult - no longer optically transparent - stages are limited. To improve these aspects, we developed imaging-based 3D models of the cardiovascular system of wild-type adult zebrafish.

METHODS

In vivo high-frequency echocardiography and ex vivo synchrotron x-ray tomography were combined to build fluid-structure interaction finite element models of the fluid dynamics and biomechanics inside the ventral aorta.

RESULTS

We successfully generated a reference model of the circulation in adult zebrafish. The dorsal side of the most proximal branching region was found as the location of highest first principal wall stress and was also a location of low wall shear stress. Reynolds number and oscillatory shear were very low compared to mice and humans.

SIGNIFICANCE

The presented wild-type results provide a first extensive biomechanical reference for adult zebrafish. This framework can be used for advanced cardiovascular phenotyping of adult genetically engineered zebrafish models of cardiovascular disease, showing disruptions of the normal mechano-biology and homeostasis. By providing reference values for key biomechanical stimuli (including wall shear stress and first principal stress) in wild-type animals, and a pipeline for image-based animal-specific computational biomechanical models, this study contributes to a more comprehensive understanding of the role of altered biomechanics and hemodynamics in heritable cardiovascular pathologies.

Local TGF-beta sequestration by fibrillin-1 regulates vascular wall homeostasis in the thoracic aorta

Background

Aortic dissection and rupture is the main cause of early cardiovascular mortality in patients with Marfan syndrome (MFS). MFS is caused by a defect in fibrillin-1, a building block of microfibrils in the extracellular matrix which binds transforming growth factor beta (TGF-beta) via interaction with latent TGF-beta binding proteins (LTBPs). Multiple mouse models, both pharmaceutically induced and genetically manipulated, have been used to investigate the pathophysiology and biomechanical aspects of thoracic aortic aneurysms and dissections. However, the role of TGF-beta in MFS has been controversial, with earlier studies suggesting that excess release of TGF-beta due to decreased interaction with dysfunctional fibrillin-1 leads to aortic dilation and vascular damage, while other studies have shown an important protective effect of TGF-beta. Studying dedicated mouse models for MFS, with defects interfering with TGF-beta binding and -function may help resolve these discrepancies.

Purpose

This study aimed to reveal insights in the role of TGF-beta signaling in aneurysm formation and dissection in MFS.

Methods

Mice lacking the fibrillin-1 binding site for LTBPs (Fbn1H1Δ/+ and Fbn1H1Δ/H1Δ), mice with a truncated fibrillin-1 (Fbn1GT-8/+), and mice with a combination of both alleles (Fbn1GT-8/ H1Δ) were subjected to in vivo cardiac ultrasound analysis. Ex vivo phase-contrast synchrotron X-ray imaging was performed at the Paul Scherrer Institute to visualize the elastic lamellae architecture in the vascular wall of the entire excised thoracic aorta in a subset of mice from each group.

Results

Fbn1GT-8/+, Fbn1 H1Δ/+ and Fbn1H1Δ/H1Δ mice had a normal life span, but Fbn1GT-8/ H1Δ mice showed increased mortality due to aortic rupture starting at 4–5 months of age. The aortic root was dilated both in Fbn1GT-8/+ and Fbn1GT-8/ H1Δ mice at 6 months of age, but not in Fbn1H1D/+ or Fbn1H1Δ/H1Δ mice. Synchrotron images showed significant elastic lamellae fragmentation in the thoracic aortic wall of Fbn1GT-8/+ mice, and to a larger extent in Fbn1GT-8/ H1Δ mice. Surprisingly, localized elastin fragmentation was also found in the ascending thoracic aorta of Fbn1 H1Δ/+ and Fbn1H1Δ/H1Δ mice, despite a lack of aortic aneurysm formation. Moreover, Fbn1H1Δ/H1Δ mice displayed more severe aortic wall damage. The localized microdissections found in these mouse models were characterized by a severe alteration of the elastic fiber organization, cellular influx and increased collagen deposition, as confirmed by histological analysis.

Conclusions

Our data suggest that loss of LTBP binding to fibrillin-1 leads to the development of localized microdissections in the aorta in the absence of aortic aneurysm, and exacerbates the aortic wall morphology abnormalities in mice with truncated fibrillin-1. We therefore hypothesize that local TGF-beta sequestration is required to maintain aortic homeostasis.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Foundation for Cardiac Surgery (“VZW Fonds voor Hartchirurgie”), grant No. 489644Baillet-Latour Grant for Medical Research

Ultra-high speed X-ray imaging of dynamic fracturing in cementitious materials under impact

In this work the dynamic fracturing of an ultra-high strength cementitious material is probed with in-situ ultra-high speed X-ray phase-contrast diagnostics to investigate the phenomenology of dynamic fracture. Gas gun experiments were conducted on two characteristic samples with two different impact speeds, namely 80 and 190 m/s using the edge-on impact test configuration. The samples were placed within the intense X-ray beam providing an observation field of 12.8 mm in width and 8 mm in height. Thanks to equispaced 16 bunches of short X-ray pulses, the samples were imaged through an indirect detector arrangement using the Shimadzu HPV-X2 camera lens-coupled to a fast scintillator capturing through-thickness measurements with an interframe time of 1.06 µs. The comparison of fragmentation patterns between two samples revealed an important insight into velocity dependant spall formation as well as the effects of crack closure and bridging.

In-situ visualization of sound-induced otolith motion using hard X-ray phase contrast imaging

Regarding the basics of ear structure-function relationships in fish, the actual motion of the solid otolith relative to the underlying sensory epithelium has rarely been investigated. Otolith motion has been characterized based on a few experimental studies and on approaches using mathematical modeling, which have yielded partially conflicting results. Those studies either predicted a simple back-and-forth motion of the otolith or a shape-dependent, more complex motion. Our study was designed to develop and test a new set-up to generate experimental data on fish otolith motion in-situ. Investigating the basic parameters of otolith motion requires an approach with high spatial and temporal resolution. We therefore used hard X-ray phase contrast imaging (XPCI). We compared two anatomically well-studied cichlid species, Steatocranus tinanti and Etroplus maculatus, which, among other features, differ in the 3D shape of their otoliths. In a water-filled tank, we presented a pure tone of 200 Hz to 1) isolated otoliths embedded in agarose serving as a simple model or 2) to a fish (otoliths in-situ). Our new set-up successfully visualized the motion of otoliths in-situ and therefore paves the way for future studies evaluating the principles of otolith motion.

Hard X-ray phase-contrast tomography of non-homogeneous specimens: grating interferometry versus propagation-based imaging

X-ray phase-contrast imaging is an effective approach to drastically increase the contrast and sensitivity of microtomographic techniques. Numerous approaches to depict the real part of the complex-valued refractive index of a specimen are nowadays available. A comparative study using experimental data from grating-based interferometry and propagation-based phase contrast combined with single-distance phase retrieval applied to a non-homogeneous sample is presented (acquired at beamline ID19-ESRF). It is shown that grating-based interferometry can handle density gradients in a superior manner. The study underlines the complementarity of the two techniques for practical applications.

X-ray Bragg magnifier microscope as a linear shift invariant imaging system: image formation and phase retrieval

We present the theoretical description of the image formation with the in-line germanium Bragg Magnifier Microscope (BMM) and the first successful phase retrieval of X-ray holograms recorded with this imaging system. The conditions under which the BMM acts as a linear shift invariant system are theoretically explained and supported by the experiment. Such an approach simplifies the mathematical treatment of the image formation and reconstruction as complicated propagation of the wavefront onto inclined planes can be avoided. Quantitative phase retrieval is demonstrated using a test sample and a proof of concept phase imaging of a spider leg is also presented.