Fiber Fragmentation Research Articles

The Ability of Gastropods of Lake Baikal to the Feeding and Excretion of Microplastic Particles with Different Morphological Structures

Studies of the pollution of Lake Baikal with microplastic particles have been started quite recently. Almost all research is focused on the assessment of surface water pollution, while the impact of microplastics on Baikal organisms remains unexplored. We conducted a laboratory experiment involving three species of gastropod mollusks, the Palearctic Lymnaea stagnalis (L., 1758) and Radix auricularia (L., 1758), as well as the Baikal endemic Benedictia baicalensis (Gerstfeldt, 1859). Two types of microplastics were used in the experiment: fragments of polystyrene and polyester fibers, prepared independently in the laboratory. These plastic particles, along with the food mixture, were placed in aquariums with mollusks. In total, as a result of the experiment, 386 preparations with mollusk excrement were obtained, of which 144 preparations were for the Radix auricularia species, 176 for the Lymnaea stagnalis species, and 67 for the Benedictia baicalensis species, the experiment with the latter species was carried out only with microplastic fragments. All preparations were analyzed according to the degree of fluorescence. The data were statistically processed using Spearman’s rank correlation coefficient. The data obtained allowed us to conclude that gastropods of these species are able to absorb microplastic particles and remove them from the body. However, the rate of removal of microplastic particles from the body of a mollusk is species-specific, and also directly depends on the morphological structure of microplastic particles.

Sustainable Composites from Waste Polypropylene Added with Thermoset Composite Waste or Recovered Carbon Fibres

In order to limit the ever-increasing consumption of new resources for material formulations, regulations and legislation require us to move from a linear to a circular economy and to find efficient ways to recycle, reuse and recover materials. Taking into account the principles of material circularity and waste reuse, this research study aims to produce thermoplastic composites using two types of industrial waste from neighbouring companies, namely waste polypropylene (wPP) from household production and carbon-fibre-reinforced epoxy composite scrap from a pultrusion company. The industrial scrap of the carbon-fibre-reinforced epoxy composites was either machined/ground to powder (pCFRC) and used directly as a reinforcement agent or subjected to a chemical digestion process to recover the carbon fibres (rCFs). Both pCFRC and rCF, at different weight ratios, were melt-blended with wPP. Prior to melt blending, both pCFRC and rCF were analysed for morphology by scanning electron microscopy (SEM). The pCFRC powder contains epoxy resin fragments with spherical to ellipsoidal shape and carbon fibre fragments. The rCFs are clean from the matrix, but they are slightly thicker and corrugated after the matrix digestion. Further, the morphologies of wPP/pCFRC and wPP/rCF were also investigated by SEM, while the thermal behaviour, i.e., transitions and changes in crystallinity, and thermal resistance were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The strength of the interaction between the filler (i.e., pCFRC or rCF) and the wPP matrix and the processability of these composites were assessed by rheological studies. Finally, the mechanical properties of the systems were characterised by tensile tests, and as found, both pCFRC and rCF exert reinforcement effects, although better results were obtained using rCF. The wPP/pCFRC results are more heterogeneous than those of the wPP/rCF due to the presence of epoxy and carbon fibre fragments, and this heterogeneity could be considered responsible for the mechanical behaviour. Further, the presence of both pCFRC and rCF leads to a restriction of polymer chain mobility, which leads to an overall reduction in ductility. All the results obtained suggest that both pCFRC and rCF are good candidates as reinforcing fillers for wPP and that these complex systems could potentially be processed by injection or compression moulding.

Diseased Tendon Models Demonstrate Influence of Extracellular Matrix Alterations on Extracellular Vesicle Profile.

Tendons enable movement through their highly aligned extracellular matrix (ECM), predominantly composed of collagen I. Tendinopathies disrupt the structural integrity of tendons by causing fragmentation of collagen fibers, disorganization of fiber bundles, and an increase in glycosaminoglycans and microvasculature, thereby driving the apparent biomechanical and regenerative capacity in patients. Moreover, the complex cellular communication within the tendon microenvironment ultimately dictates the fate between healthy and diseased tendon, wherein extracellular vesicles (EVs) may facilitate the tendon's fate by transporting biomolecules within the tissue. In this study, we aimed to elucidate how the EV functionality is altered in the context of tendon microenvironments by using polycaprolactone (PCL) electrospun scaffolds mimicking healthy and pathological tendon matrices. Scaffolds were characterized for fiber alignment, mechanical properties, and cellular activity. EVs were isolated and analyzed for concentration, heterogeneity, and protein content. Our results show that our mimicked healthy tendon led to an increase in EV secretion and baseline metabolic activity over the mimicked diseased tendon, where reduced EV secretion and a significant increase in metabolic activity over 5 days were observed. These findings suggest that scaffold mechanics may influence EV functionality, offering insights into tendon homeostasis. Future research should further investigate how EV cargo affects the tendon's microenvironment.

From Fabric to Fallout: A Systematic Review of the Impact of Textile Parameters on Fibre Fragment Release

From Fabric to Fallout: A Systematic Review of the Impact of Textile Parameters on Fibre Fragment Release

Microplastics characterization, abundance and distribution on the coast of Ordu province (Türkiye)

Plastics, one of the most common materials polluting our seas, are now a serious global problem. These plastics persist in our environment for a long time and gradually turn into much smaller particles that we call microplastics (MPs). In this study, the MPs profile of sand and seawater samples taken from 6 different stations from the coasts of Ordu Province was analysed in detail. As a result of MPs and μ FTIR spectroscopic analyses, the presence of MPs in sand and seawater samples was determined and their characterisation, abundance and distribution characteristics were revealed. In this study, 291.11 items kg-1 MPs was found in sediment samples and 0.263 items L-1 MPs in water samples. A total of 420 MP fragments were detected from seawater and sand samples on the coasts of Ordu Province and analysed for colour, shape, size and species. Fibre and film type MPs fragments were found the most and it was determined that these fragments were generally blue and transparent in colour. It was observed that MPs were commonly in the size range of 0-50µm (50.71%) and the detected MPs were not larger than 800 µm. Most of the MPs observed were polyethylene (56%), followed by polypropylene (19%), polystyrene (15%), polyvinyl acetate (7%) and polytylene tereftelate (3%). In conclusion, MPs pose serious threats to human health and the environment, and it is recommended that waste generation should be reduced, necessary precautions should be taken, monitoring studies should be carried out and necessary removal methods should be applied in order to reduce the risk caused by wastes released into the seas.

Exploring anisotropic mechanical properties of lobster claw exoskeleton through fractal models

The outstanding mechanical properties of lobster claw exoskeletons are intricately tied to their internal microstructure. Investigating this relationship can offer vital insights for designing high-performance additive manufacturing structures. Fractal theory, with its fractional dimensional perspective, suits the complexity of real-world phenomena. Our study examines fully hydrated lobster claw exoskeletons using a multifaceted approach: four-point bending tests, scanning electron microscopy observations, and fractal models. Test results reveal superior mechanical properties in longitudinal specimens. Scanning electron microscopy shows non-uniform fiber helical structures and porous elements in the exoskeleton. Fracture mechanisms involve both breaking fiber fragments perpendicular to the cross-section and tearing between these fragments. The observed crack propagation paths exhibit statistical self-similarity. Consequently, we develop fractal models for the crack propagation paths in longitudinal and transverse specimens, calculating crack extension forces. Using the box-counting method and its improved variant, we determine the fractal dimensions of specimen sections. The fractal dimension of longitudinal models exceeds that of transverse models, and calculated crack extension forces are higher in longitudinal models. These findings align well with experimental data, demonstrating fractal theory's efficacy in analyzing the lobster claw exoskeleton's anisotropic mechanical properties.

Characterization and Techno-Functional Properties of High Protein Walnut Flour from an Oil by-Product.

A high protein walnut flour (HPWF) was obtained by defatting walnut flour (WF), which is a by-product of the oil industry. The objective of this study was the chemical and techno-functional characterization of HPWF. Composition, amino acid content, protein secondary structure, protein solubility and thermal transitions were measured. Besides, the techno-functional properties, emulsion activity and stability, and water holding and oil absorption capacities, of HPWF were evaluated. Also, the molecular mass of proteins under denaturing conditions and the microstructure of HPWF were evaluated by electrophoresis and confocal scanning laser microscopy, respectively. HPWF had 55.4% protein content and 21.5% total dietary fibre. In terms of HPWF amino acid composition, the limiting amino acids were the sulphurated cysteine and methionine. By FTIR analysis, the main secondary structures were β-sheet (49%) followed by α-helix (24%); both structures are considered to be ordered. Likewise, HPWF soluble proteins increased at basic pH and HPWF proteins were separated in 11 bands with molecular masses ranging from 97 kDa to 18kDa by electrophoresis. With respect to techno-functional properties, HPWF presented good emulsion activity (51%) and high thermal emulsion stability (46%). In addition, HPWF retained 571% and 242% of water and oil by weight, respectively. Finally, the micrograph showed the predominance of protein structures and fibre fragments, and the presence of few lipids mostly trapped. These results showed that HPWF is an interesting source of plant-based proteins and walnut flour can be used to obtain high protein ingredients from non-traditional sources.

Comprehensive analysis of pseudoxanthoma elasticum: epidemiological, genetic, and clinical findings from the leading Italian center.

Pseudoxanthoma elasticum (PXE) is a rare genetic autosomal recessive metabolic disease characterized by progressive mineralization and fragmentation of elastic fibers from soft connective tissues. The objective of our study was to analyze the epidemiological, genetic, cutaneous, and extracutaneous clinical data from the largest Italian monocentric cohort of PXE patients. We included all patients diagnosed with PXE and referred to Neurocutaneous Rare Diseases at Umberto I Polyclinic Hospital (Rome, Italy) between January 1983 and February 2024. A retrospective analysis of their data was performed. We enrolled 86 patients (77.9% women), revealing compound heterozygosity in 19.8% of cases and homozygosity in 5.8%. Missense (34.9%), non-sense (5.8%), splice-site (5.8%), deletion (4.7%), and frameshift (2.3%) mutations were disclosed. Cutaneous alterations were noted in the neck (69.7%), axilla (33.7%), inguinal (17.5%), and cubital folds (11.7%). The most common ocular findings were angioid streaks (64.0%) and choroidal neovascularization (18.6%), with blindness reported in 5.8% of cases. Thicker intima-media was observed around the mid-fifties in the supra-aortic trunks (40.7%), lower limb arteries (32.6%), and renal arteries (4.7%). Regurgitation was more common in atrioventricular valves (48.8%) than in semilunar ones (10.5% and 9.3%). Dyslipidemia (19.8%), hypertension (18.8%), and fatty liver disease (12.8%) were prevalent, with calcifications found in the kidneys (25.6%), liver (15.1%), spleen (11.6%), and testicles (8.1% of males). Autoimmune diseases and depression were observed in 11.6% and 4.7% of cases, respectively. Enhanced understanding of PXE can improve patients' quality of life and facilitate the development of more effective therapeutic strategies.

Confocal Microscopy of the Cornea in Aqueous-Deficient Dry Eye Disease-A Literature Review.

In vivo confocal microscopy (IVCM) is a vital tool in studying dry eye disease (DED), providing insights into morphological changes at ocular surface unit levels. This review presents the main differences in corneal structure between aqueous-deficient dry eye disease (AD-DED) and normal eyes. A comprehensive search of PubMed, Web of Science, Embase, and MEDLINE databases from January 2000 to December 2023 was conducted. The study selection process, as well as data selection and examination, were independently performed by two members of the review team. The review reveals a consistent decrease in corneal surface epithelial cell density in AD-DED cases compared to a control group, but conflicting data on basal epithelial cell density. Notably, the abnormal hyperreflectivity of keratocytes in patients with Sjogren's syndrome was recorded, and there was a significant keratocyte density in AD-DED subjects compared to evaporative DED and control groups. Studies also found a decrease in sub-basal nerve density, increased tortuosity, and the fragmentation of nerve fibers. Dendritic cell density and dendritic cell dendrites increase in AD-DED patients compared to healthy subjects. IVCM is a powerful tool for enhancing our understanding of the pathophysiological mechanisms underlying DED. However, the review underscores the urgent need to standardize the terminology, analysis, and units used for accurate interpretation, a crucial step in advancing our knowledge of DED.

From Biomechanical Properties to Morphological Variations: Exploring the Interplay between Aortic Valve Cuspidity and Ascending Aortic Aneurysm.

Background: This research explores the biomechanical and structural characteristics of ascending thoracic aortic aneurysms (ATAAs), focusing on the differences between bicuspid aortic valve aneurysms (BAV-As) and tricuspid aortic valve aneurysms (TAV-As) with non-dilated aortas to identify specific traits of ATAAs. Methods: Clinical characteristics, laboratory indices, and imaging data from 26 adult patients operated on for aneurysms (BAV-A: n = 12; TAV-A: n = 14) and 13 controls were analyzed. Biomechanical parameters (maximal aortic diameter, strain, and stress) and structural analyses (collagen fiber organization, density, fragmentation, adipocyte deposits, and immune cell infiltration) were assessed. Results: Significant differences in biomechanical parameters were observed. Median maximal strain was 40.0% (control), 63.4% (BAV-A), and 45.3% (TAV-A); median maximal stress was 0.59 MPa (control), 0.78 MPa (BAV-A), and 0.48 MPa (TAV-A). BAV-A showed higher tangential modulus and smaller diameter, with substantial collagen fragmentation (p < 0.001 vs. TAV and controls). TAV-A exhibited increased collagen density (p = 0.025), thickening between media and adventitia layers, and disorganized fibers (p = 0.036). BAV-A patients had elevated adipocyte deposits and immune cell infiltration. Conclusions: This study highlights distinct pathological profiles associated with different valve anatomies. BAV-A is characterized by smaller diameters, higher biomechanical stress, and significant collagen deterioration, underscoring the necessity for tailored clinical strategies for effective management of thoracic aortic aneurysm.

Fibre fragment pollution: source directed intervention through design

This study analyses the difference in fibre fragment pollution generated during the laundering of woven and knit fabrics for clothing and the influence of fabric parameters on the amount of pollution released. 100% polyester single jersey knit and 2/2 twill woven fabrics were created and washed according to AATCC TM212-2021. Results indicated more tightly woven structures released over three times less pollution than looser knit structures, releasing 6.41 mg of fibre fragments per kg of woven fabric (mean ± 1.50 SD, n = 8) compared to 21.21 mg of fibre fragments per kg of knit fabric (mean ± 1.80 SD, n = 8). The first wash for both knit and woven fabrics shed significantly more fibre fragments than subsequent washes. By the fifth wash both fabrics released under a tenth of the amount of pollution released in the first wash. To mitigate fibre fragment pollution that is released by fabrics designed for clothing this work recommends designing out pollution using more tightly constructed fabrics. Furthermore, the implementation of technology in fabric and garment manufacturing processes (e.g. fibre catching devices) should be utilised specifically during first washes allowing pollution to be filtered from the wastewater to stem the flow of contaminants into the environment.

Enhanced ballistic resistance of SiC ceramic-fiber composite armor: an investigation of fiber laminate backing effects and fragmentation dynamics

Enhanced ballistic resistance of SiC ceramic-fiber composite armor: an investigation of fiber laminate backing effects and fragmentation dynamics

Raman spectroscopic stress mapping of single high modulus carbon fibre composite fragmentation in compression

Fragmentation of high modulus carbon fibres is relevant to the failure mechanisms of advanced polymer matrix composites in compression. In situ spatially-resolved Raman spectroscopy during the fragmentation of model single fibre composites is used to map local stress distributions during failure events. The characteristic graphitic band (the G band) located around 1580 cm−1 is associated with the in-plane carbon-carbon bonds; this band shifts its position, and can be calibrated, with the local axial stress in the fibre. The analysis maps the evolution of local stresses with increasing overall composite compression strain, identifying a series of critical events, including fibre fracture, interfacial debonding, and the formation of inter-fragment ‘wedges’. Fitting shear lag models provides interfacial shear strength values. Multiple failure maps of two examples of high modulus PAN carbon fibres (M46J and M55J) demonstrate the possibility of local fragment bending due to fragment end contact. A timeline of potential fragmentation events is proposed for carbon fibres undergoing compression.

Biodegradation behavior of wool and other textile fibers in aerobic composting conditions

AbstractPollution of the environment by microscopic fragments of plastic is a growing environmental concern. A category of this pollution is fiber fragments from textiles, a source of which is believed to be fibers released by clothing made of synthetic fibers during laundering. These fragments could enter the environment at the end of the textile’s useful life if it is not re-used or recycled. Disposal of biodegradable fibers could be achieved by industrial composting, but natural fibers are sometimes modified during manufacturing in ways that might influence biodegradation. The composting behavior of fabrics made with unmodified and chemically modified wool fibers (chlorine-Hercosett treated), regenerated cellulose, and several synthetic fibers was compared in industrial composting conditions according to an established standard test method. The fabrics were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray and electron microscopy. The regenerated cellulose (viscose rayon) biodegraded to the greatest extent in the test, and both types of wool also biodegraded readily. All three synthetic fibers had no biodegradation. The machine-washable wool biodegraded more rapidly than unmodified wool and analysis of residues at the conclusion of the test indicated that it did not generate non-degradable fiber fragments. The epicuticle of unmodified wool is covered with a hydrophobic layer, which may resist microbial attack, but with time this slowly degraded. Conversely, the machine-washable wool is hydrophilic and therefore was easier for microbes to attack. If not re-used, commercial, machine-washable wool textiles can be readily disposed of in industrial composting conditions.

Association of artificial intelligence–derived collagen disorder architecture (CoDA) features with survival outcome and objective response to immune checkpoint inhibitors in patients with head and neck squamous cell carcinoma.

6061 Background: In several cancers, including head and neck squamous cell carcinoma (HNSCC), the immunosuppressive components of the tumor microenvironment (TME) can impact the effectiveness of immune checkpoint inhibitors (ICI). One significant component of the TME is the extracellular matrix, which is rich in collagen fibers. In this work we used machine learning and image analysis approaches on whole slide images (WSIs) to characterize collagen disorder architecture (CoDA) features and evaluated their association with outcomes in HNSCC patients receiving ICI. Methods: WSIs of HNSCC patients treated with ICI were obtained from University Hospitals (S1, n=43) and Emory University (S2, n=31). Tiles from the tumor annotated regions of the WSIs were extracted, and a derivative-of-Gaussian model was used to identify collagen fibers in the stroma of these tiles. Various CoDA features were then calculated as follows: (1) collagen fiber fragmentation measure, (2) collagen fiber bundling percentage, (3) collagen fiber rigidity measure, (4) collagen fiber anisotropy index and (5) collagen fiber density index. CoDA features of S1and S2 were combined and split into 50:50 for training and validation. For survival analysis using overall survival (OS) as endpoint, the median risk score in the training set was applied for risk stratification in the validation set by means of a Least Absolute Shrinkage and Selection Operator (LASSO) and Cox regression model. For predictive analysis, CoDA features from patients with objective response (OR) to ICI were identified (S1, non-responder=23, responder=20), (S2, non-responder=23, responder=8). The top features were then selected using the LASSO and combined with a Generalized Linear Model classifier. A 5-fold cross-validation assessed Area Under the Receiver Operating Characteristics Curve (AUC) for predicting OR, with average AUC as the final performance metric in the validation set. Results: For survival analysis, high risk patients in the validation set had worse survival than low risk patients (HR=2.7 (95% CI=1.1-6.6, p=0.02)). For predicting OR, the selected top CoDA features were collagen fiber fragmentation measure, collagen fiber bundling percentage, collagen fiber rigidity measure and collagen fiber density index and the average AUC was 0.64±0.16. More fragmentation of the collagen fibers along with dense thick bundles and straightened fibers were observed in the WSIs of non-responder patients to ICI. Conclusions: High risk CoDA features correlated with worse survival in patients with HNSCC receiving ICI. Also, we established a correlation of specific CoDA features with OR to ICI. The prognostic and predictive value of CoDA deserves additional exploration with confirmatory data from larger, independent multi-site validation.

Investigation of friction and vibration performance of lithium complex grease containing candle soot on aviation electrical machine

The prolonged operation of the motor in the all-electric aircraft can cause the fragmentation and shortening of grease thickener fibers, ultimately resulting in the lubricating grease becoming ineffective. In order to avoid grease failure causing motor winding burnout, this paper uses a four-ball friction testing machine to test the tribological properties of six composite greases containing candle soot with different concentrations, and analyzes the changes in friction coefficient and wear diameter. In addition, by building a test platform for motor vibration and noise, this paper studies the influence of lithium complex grease on vibration and noise characteristics of aviation electrical machine at different propeller speeds. The results show that the addition of 0.04 wt% candle soot lithium grease has the best tribological properties and vibration inhibition properties, because the candle soot in the oil film changes the sliding friction into rolling friction in the contact area of some friction pair. The temperature rise test of aviation electrical machine shows that the lithium complex grease plays an active role in the heat dissipation performance of the high-speed rotating motor.

Improved fiber orientation measurement in nonwovens with corner removal

The orientation of fibers or filaments in nonwovens is critical in determining their mechanical characteristics. Image processing techniques, prized for their minimal human intervention and rapid processing speed, are widely utilized in nonwoven fiber orientation measurement. However, these techniques often face substantial challenges, such as low accuracy in corner detection, errors in fiber segmentation, and inefficiencies in fiber orientation calculation. Addressing these concerns, this study introduces a novel, enhanced method accompanied by two innovative optimization algorithms to enhance accuracy. The first innovation involves the development of a newly developed fiber corner detection algorithm, dubbed the T-detector, specifically tailored for the unique characteristics of fiber images, enabling efficient corner point detection and removal. Subsequently, we introduce and employ a fiber length restriction algorithm to further segment the processed longer fibers into the remaining fiber fragments and utilize a skeleton projection algorithm to calculate the fiber orientation. These algorithms overcome the existing technology’s inherent shortcomings, thereby heightening measurement accuracy. The results illustrate an improvement in measurement precision over other orientation distribution measurement algorithms, with the fiber information retention (covering ratio) reaching an impressive 95%. Our proposed method not only calculates fiber orientation distribution in nonwovens with remarkable accuracy and efficiency, but its innovative approach also stands to provide a theoretical foundation for the design of three-dimensional filtering models with specific fiber orientation.

Baicalin attenuates acute skin damage induced by ultraviolet B via inhibiting pyroptosis

As the outermost layer of the human body, the skin suffers from various external factors especially light damage, among which ultraviolet B (UVB) irradiation is common and possesses a relatively high biological damage capacity. Pyroptosis is a newly discovered type of programmed cell death, which can induce cell rupture and induce local inflammatory response. However, the molecular mechanisms of pyroptosis in photodamaged skin is poorly understood. Baicalin, a flavonoid extracted from the desiccated root of Scutellaria baicalensis Georgi (Huang Qin). Despite its antioxidant abilities, whether baicalin protects skin by attenuating UVB-induced pyroptosis remains unclear, which was the aim of this study. The UVB-induced acute skin damage model was established by using human immortalized keratinocytes (HaCaT cells) and Kunming (KM) strain mice. The protective dose selection for baicalin is 50 μM in vitro and 100 mg/kg in vivo. In in vitro study, UVB irradiation significantly decreased cell viability, increased cell death and oxidative stress in HaCaT cells, while pretreatment with baicalin improved these phenomena. Furthermore, the baicalin pretreatment notably suppressed nuclear factor kappa B (NF-κB) translocation, the NLRP3 inflammasome activation and gasdermin D (GSDMD) maturation, thus effectively attenuating UVB-induced pyroptosis. In in vivo study, the baicalin pretreatment mitigated epidermal hyperplasia, collagen fiber fragmentation, oxidative stress and pyroptosis in UVB-irradiated mouse skin. In a nutshell, this study suggests that baicalin could be a potential protective agent to attenuate acute skin damage induced by UVB irradiation through decreasing oxidative stress and suppressing NF-κB/NLRP3/GSDMD-involved pyroptosis.

Fibulin-5 Is Required for Small Artery Development and Function

Introduction: Fibulins are a family of eight extracellular matrix proteins with diverse functions. Fibulin-4 and -5 (FBLN-4 and -5), in particular, have been shown to be important for elastic fiber assembly. Mutations in each of the genes lead to cutis laxa, a syndrome characterized by loose skin with variable organ involvement, particularly in the vasculature, lungs and skeleton. We recently characterized a mouse model carrying a disease-causing mutation in Fbln4 (E57K) and, contrary to conduit arteries that had elastic fiber fragmentation and stiffness, Fbln4E57K resistance arteries were structurally intact. Functionally however, Fbln4E57K mesenteric arteries exhibited endothelial dysfunction secondary to increased shear stress from large artery stiffness. Loss of FBLN5 has been shown to lead to elastic fiber fragmentation in conduit arteries, but the consequences of its loss on resistance arteries are unknown. Therefore, the objectives of this study were to determine the structural and functional consequences of FBLN5 loss on resistance arteries. Methods: We utilized adult Fbln5 knock-out (KO) mice and examined the ultrastructure of renal and mesenteric arteries via transmission electron microscopy. Functionally, using pressure myography, we characterized the myogenic tone and reactivity of Fbln5 KO and littermate control third-order mesenteric arteries to various vasoactive substances including acetylcholine, papaverine, angiotensin II, phenylephrine and potassium chloride. Results: While the internal elastic lamina (IEL) of Fbln5KO mice resistance arteries was largely intact, the external elastic lamina (EEL) was nearly absent. Similar to Fbln4E57K mice, Fbln5KO mesenteric arteries exhibited impaired endothelial-dependent vasorelaxation, likely secondary to proximal large artery stiffness. Unlike Fbln4E57K mesenteric arteries however, Fbln5 KO mesenteric arteries exhibited increased myogenic tone as well as a hypercontractile response to angiotensin II and potassium chloride, but not to phenylephrine. Conclusions: In addition to highlighting differences in the requirements for elastic fiber assembly along the arterial tree, these data emphasize the differential contribution of FBLN4 and FBLN5 to IEL vs. EEL in resistance arteries and suggest pathway-specific changes in smooth muscle cell contractility secondary to FBLN5 deficiency. This work was supported by the Washington University Pediatric Nephrology Research Core Pilot Grant Program to CMH. Funds were also provided by The Department of Pediatrics at Washington University in St. Louis School of Medicine to CMH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 2021: 18 F-Sodium Fluoride Positron Emission Tomography To Assess Thoracic Aortopathy In Bicuspid Aortic Valve Disease

Background: Bicuspid aortic valve is associated with thoracic aortopathy with many patients suffering aortic dissection below the aortic diameter threshold for prophylactic aortic replacement surgery. In aortopathy, the aortic wall media initially undergoes increasing microcalcification due to elastin fibre fragmentation but with disease progression, elastin fibre degradation leads to loss of aortic microcalcification. 18 F-Sodium fluoride positron emission tomography (PET) is a non-invasive method of detecting arterial microcalcification that has been successfully used in cardiovascular disease risk stratification. Aims: To determine if aortic 18 F-sodium fluoride imaging can identify aortopathy and predict subsequent disease progression in patients with bicuspid aortic valve disease. Methods: In this prospective cohort study, 77 patients with bicuspid aortic valve from clinical sites across Scotland and 18 healthy volunteers, underwent 18 F-sodium fluoride PET-computed tomography (PET-CT) followed immediately by PET-magnetic resonance imaging (PET-MRI). Maximum standardised uptake values (SUVmax) were determined in the ascending aorta. Aortic diameters were measured in aortic axial CINE MRI sequences. Patients were followed-up at 24 months with a further PET-MRI. Annualised change in aortic size index (mm/m 2 /year) and annualised change in SUVmax stratified in tertiles were calculated. Results: Patients with bicuspid aortic valve disease had higher SUVmax than control subjects, especially in those with aortic dilatation. Baseline SUVmax was associated with annualised aortic expansion rate independent of baseline aortic size (β=0.45, p=0.001). Patients in tertile 1 (loss of SUVmax over time) exhibited greater aortic growth (0.60±0.50 mm/m 2 /year) than those with stable SUVmax (tertile 2, 0.26±0.36 mm/m 2 /year) or increasing SUVmax (tertile 3, 0.24±0.36 mm/m 2 /year; p=0.01). Conclusion: Aortic microcalcification activity is increased in aortopathy of patients with bicuspid aortic valve. Loss of aortic microcalcification is associated with more rapid disease progression and represents a promising new approach to the identification of patients at higher risk of aortic complications.