Changes In Tissue Composition Research Articles

Biomolecular modifications in the sacfry of Mogurnda adspersa in response to copper stress

Copper (Cu) is one of the most harmful contaminants in fresh-water systems. Fish larvae such as sacfry are particularly vulnerable to metals such as copper (Cu) due to a less-developed excretory organ system and permeable skin that can absorb metals directly from the water. However, the sublethal effects of metals on this life stage are not well understood. This study assessed the sublethal toxicity of Cu on purple-spotted gudgeon sacfry (PSG, Mogurnda adspersa). For this purpose, 96h Cu toxicity bioassays were performed and toxic effects of Cu on PSG were measured at different levels of biological organization, from the individual (loss of equilibrium, wet weight), to tissue (chemical changes in retinal tissue composition) and molecular responses (whole body amino acid (AA) profiles). The EC10 and EC50 (ECx: effect concentration that affected X% of test organisms) were found to be 12 (9 - 15) µg Cu L-1 and 22 (19 - 24) µg Cu L-1, respectively. Copper stress caused a decrease in total amino acid content and changed the AA profile of PSG compared to the controls. Proton-induced X-ray emission (PIXE) mapping techniques showed accumulation of Cu in the retinal tissues disturbing the distribution of other elements such as zinc, sulfur, phosphorus and potassium. Fourier-transform infrared (FTIR) microspectroscopy of control and Cu treated eye tissues revealed a change in protein secondary structure in retinal tissues in response to Cu accumulation, as well as decreased levels of the molecular retinal, consistent with the degradation of rhodopsin, a key protein in the visual sensory system. This is the first study to demonstrate the multi-level responses of PSG arising from exposure to environmentally realistic Cu concentrations and suggests that AA profiling can serve as a useful tool to assess the impacts of metals on fresh-water organisms.

RNA-Seq Analysis of the Growth Hormone Transgenic Female Triploid Atlantic Salmon (Salmo salar) Hepatic Transcriptome Reveals Broad Temperature-Mediated Effects on Metabolism and Other Biological Processes.

This study examined the impact of rearing temperature (10.5, 13.5 or 16.5°C) on the hepatic transcriptome of AquAdvantage Salmon (growth hormone transgenic female triploid Atlantic salmon) at an average weight of 800 g. Six stranded PE libraries were Illumina-sequenced from each temperature group, resulting in an average of over 100 M raw reads per individual fish. RNA-sequencing (RNA-seq) results showed the greatest difference in the number of differentially expressed transcripts (1750 DETs), as revealed by both DESeq2 and edgeR (q < 0.05; fold-change > |1.5|), was between the 10.5 and 16.5°C temperature groups. In contrast, 172 and 52 DETs were found in the 10.5 vs. 13.5°C and the 13.5 vs. 16.5°C comparisons, respectively. Considering the DETs between the 10.5 and 16.5°C groups, 282 enriched gene ontology (GO) terms were identified (q < 0.05), including “response to stress”, “immune system process”, “lipid metabolic process”, “oxidation-reduction process”, and “cholesterol metabolic process”, suggesting elevated temperature elicited broad effects on multiple biological systems. Pathway analysis using ClueGO showed additional impacts on amino acid and lipid metabolism. There was a significant positive correlation between RNA-seq and real-time quantitative polymerase chain reaction (RT-qPCR) results for 8 of 9 metabolic-related transcripts tested. RT-qPCR results also correlated to changes in fillet tissue composition previously reported in these salmon (e.g., methionine and lysine concentrations positively correlated with hsp90ab1 transcript expression), suggesting that rearing temperature played a significant role in mediating metabolic/biosynthetic pathways of AquAdvantage Salmon. Many transcripts related to lipid/fatty acid metabolism (e.g., elovl2, fabpi, hacd2, mgll, s27a2, thrsp) were downregulated at 16.5°C compared to both other temperature groups. Additionally, enrichment of stress-, apoptosis- and catabolism-relevant GO terms at 16.5°C suggests that this temperature may not be ideal for commercial production when using freshwater recirculating aquaculture systems (RAS). This study relates phenotypic responses to transcript-specific findings and therefore aids in the determination of an optimal rearing temperature for AquAdvantage Salmon. With approval to grow and sell AquAdvantage Salmon in the United States and Canada, the novel insights provided by this research can help industry expansion by promoting optimal physiological performance and health.

Cardiac Magnetic Resonance Features of Fabry Disease: From Early Diagnosis to Prognostic Stratification.

In the past few years, the wide application of cardiac magnetic resonance (CMR) significantly changed the approach to the study of cardiac involvement in Fabry Disease (FD). The possibility to perform non-invasive tissue characterization, including new sequences such as T1/T2 mapping, offered a powerful tool for differential diagnosis with other forms of left ventricular hypertrophy. In patients with confirmed diagnosis of FD, CMR is the most sensitive non-invasive technique for early detection of cardiac involvement and it provides new insight into the evolution of cardiac damage, including gender-specific features. Finally, CMR multiparametric detection of subtle changes in cardiac morphology, function and tissue composition is potentially useful for monitoring the efficacy of specific treatment over time. This paper aims to provide a comprehensive review of current knowledge regarding the application of CMR in FD cardiac involvement and its clinical implication.

Left Ventricular Structure, Tissue Composition, and Aortic Distensibility in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Intervention and Complications

Alterations in myocardial structure, function, tissue composition (e.g., fibrosis) may be associated with metabolic syndrome (MetS). This study aimed to determine the relation of MetS and its individual components to markers of cardiovascular disease in patients with type 1 Diabetes Mellitus (T1DM). A total of 978 subjects of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications T1DM cohort (age: 49 ± 7 years, 47% female, DM duration 28 ± 5 years) underwent cardiovascular magnetic resonance. In a subset of 200 patients, myocardial tissue composition was measured with cardiovascular magnetic resonance T1 mapping after contrast administration. MetS was defined as T1DM plus 2 other abnormalities based on the American Heart Association/National Cholesterol Education Program criteria. MetS was present in 34.1% of subjects. After adjustment for age, height, scanner, study cohort, gender, smoking, mean glycated hemoglobin levels, history of macroalbuminuria and end-stage renal disease, left ventricle mass was greater by 12.3 g, end-diastolic volume was higher by 5.4 ml, and mass to end-diastolic volume ratio was higher by 5% in patients with MetS versus those without MetS (p <0.001 for all). Myocardial T1 times were lower by 29 ms in patients with MetS than those without (p <0.001). Elevated waist circumference showed the strongest associations with left ventricle mass (+10.1 g), end-diastolic volume (+6.7 ml), and lower myocardial T1 times (+31 ms) in patients with MetS compared with those without (p <0.01). In conclusion, in a large cohort of patients with T1DM, 34.1% of subjects met MetS criteria. MetS was associated with adverse myocardial structural remodeling and change in myocardial tissue composition.

Optical Scanning System for Imaging of Heterogeneity in Biological Tissues

A non-invasive hand-held optical probe for imaging of biological tissues consists of nine units. Each unit is equipped with one red LED and three photodetectors placed at distances 7, 12, and 17 mm from the source along the x-axis. For testing, three phantoms of paraffin wax are embedded with solid inhomogeneity placed at various depths. Human biological tissues consisting of right index finger, four fingers of the same hand, and a part of the forearm below elbow joint are used. The data on optical backscattering are collected by moving the probe on the surface of phantom/tissue and after processing the respective images are obtained. Three images of the index finger show the tissue structural variation in various layers, which are in agreement with anatomical details and radiograph of the finger. The tissue details of four fingers are in agreement with that of individual finger. Similarly, the three images of the forearm show the structural variation. These observations suggest that the present technique may be used to detect tissue compositional changes below the skin.

Bone strength and composition in spacefaring rodents: systematic review and meta-analysis

Studying the effects of space travel on bone of experimental animals provides unique advantages, including the ability to perform post-mortem analysis and mechanical testing. To synthesize the available data to assess how much and how consistently bone strength and composition parameters are affected by spaceflight, we systematically identified studies reporting bone health in spacefaring animals from Medline, Embase, Web of Science, BIOSIS, and NASA Technical reports. Previously, we reported the effect of spaceflight on bone architecture and turnover in rodents and primates. For this study, we selected 28 articles reporting bone strength and composition in 60 rats and 60 mice from 17 space missions ranging from 7 to 33 days in duration. Whole bone mechanical indices were significantly decreased in spaceflight rodents, with the percent difference between spaceflight and ground control animals for maximum load of −15.24% [Confidence interval: −22.32, −8.17]. Bone mineral density and calcium content were significantly decreased in spaceflight rodents by −3.13% [−4.96, −1.29] and −1.75% [−2.97, −0.52] respectively. Thus, large deficits in bone architecture (6% loss in cortical area identified in a previous study) as well as changes in bone mass and tissue composition likely lead to bone strength reduction in spaceflight animals.

Decongestive progressive resistance exercise with an adjustable compression wrap for breast cancer-related lymphoedema (DREAM): protocol for a randomised controlled trial

IntroductionBreast cancer-related lymphoedema (BCRL) is a chronic swelling in the arm on the side of the breast cancer surgery, affecting one in five women. Recent studies in BCRL have demonstrated...

Implications of obesity for drug administration and absorption from subcutaneous and intramuscular injections: A primer.

To discuss the potential implications of obesity for drug administration and absorption from subcutaneous (SC) and intramuscular (IM) injection sites. The SC and IM routes are useful for the parenteral administration of medications to optimize pharmacokinetic properties such as time to onset and duration of effect, for cost considerations, or for ease of administration, such as when intravenous access is unavailable. The choice of SC or IM injection depends on the specific medication, with SC administration preferred for products such as insulin where a slower and more sustained response is desirable, while IM administration is usually preferred for products such as vaccines where more rapid absorption leads to a more rapid antibody response. Obesity has the potential to influence the rate and extent of absorption, as well as adverse effects, of medications administered by the SC or IM route through changes in SC tissue composition and depth or by inadvertent administration of IM medications into SC tissue because of improper needle length. Potential adverse effects associated with IM or SC injections in addition to pain, bruising, and hematoma formation include sciatic nerve injury, particularly with IM injection in the upper outer quadrant of the buttock; bone contusion or rarely osteonecrosis if the IM injection is excessively deep; and granulomas, fat necrosis, and calcification with SC injection. Issues related to medication absorption in obese patients are likely to become more prominent in the future with increasing approvals of a wide range of biotherapeutic agents administered by SC injection. Studies should be directed toward these and other agents to assist with dosing decisions in this challenging population.

Novel Magnetic Resonance Imaging Tools for the Diagnosis of Degenerative Disc Disease: A Narrative Review.

Low back pain (LBP) is one of the leading causes of disability worldwide, with a significant socioeconomic burden on healthcare systems. It is mainly caused by degenerative disc disease (DDD), a progressive, chronic, and age-related process. With its capacity to accurately characterize intervertebral disc (IVD) and spinal morphology, magnetic resonance imaging (MRI) has been established as one of the most valuable tools in diagnosing DDD. However, existing technology cannot detect subtle changes in IVD tissue composition and cell metabolism. In this review, we summarized the state of the art regarding innovative quantitative MRI modalities that have shown the capacity to discriminate and quantify changes in matrix composition and integrity, as well as biomechanical changes in the early stages of DDD. Validation and implementation of this new technology in the clinical setting will allow for an early diagnosis of DDD and ideally guide conservative and regenerative treatments that may prevent the progression of the degenerative process rather than intervene at the latest stages of the disease.

Changes in Visceral and Subcutaneous Adipose Tissue and Body Composition in Kidney Transplant Recipients at 1, 3, and 5 Years After Kidney Transplant

Body composition changes 1 year after kidney transplant (KT) have been studied extensively. However, the number of reports on midterm body composition changes has been limited. The medical records and computed tomography scans of 10 living kidney recipients (6 men, 4 women) before KT and at 1, 3, and 5 years post KT were analyzed. Each patient's body mass index was calculated, and the skeletal muscle mass was evaluated using the skeletal muscle mass index and psoas muscle mass index. Each patient's abdominal adipose tissue mass was also quantified by examining the visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and VAT/SAT ratios. These changes were assessed using repeated-measures analysis of variance. The body mass index, skeletal muscle mass index, and psoas muscle mass index values did not differ significantly between the pre-KT and 1-, 3-, and 5-year post KT measurements. Conversely, a significant difference was found in the average VAT, SAT, and VAT/SAT ratio values between the pre-KT and at 1, 3, and 5 years post KT (P < .05). The average VAT measurements before and at 1, 3, and 5 years post KT were 66, 94, 108, and 113 cm2, respectively, indicating an increasing trend over time. We observed an increase in the VAT, SAT, and VAT/SAT ratio in patients at 1, 3, and 5 years post KT.

Independent changes in bone mineralized and marrow soft tissues following acute knee injury require dual-energy or high-resolution computed tomography for accurate assessment of bone mineral density and stiffness

Musculoskeletal injuries often induce local accumulation of blood and/or fluid within the bone marrow, which is detected on medical imaging as edema-like marrow signal intensities (EMSI). In addition to its biological effects on post-injury recovery, the displacement of low-attenuating, largely adipocytic marrow by EMSI may introduce errors into quantitative computed tomography (QCT) measurements of bone mineral density (vBMD) and resulting bone stiffness estimates from image-based finite element (FE) analysis. We aimed to investigate the impact of post-injury changes in marrow soft tissue composition on CT-based bone measurements by applying CT imaging at multiple spatial resolutions. To do so, dual energy QCT (DECT) material decomposition was used to detect EMSI in the tibiae of nineteen participants with a recent anterior cruciate ligament tear. We then measured bone density and FE-based apparent modulus within the EMSI region and in a matched volume in the uninjured contralateral knee. Three measurement methods were applied: 1.) standard, QCT density calibration and density-based FEM; 2.) a DECT density calibration that provides density measurements adjusted for marrow soft tissues; and 3.) high-resolution peripheral QCT (HR-pQCT) density and microFE analyses. When measured using standard, single-energy QCT, vBMD and apparent modulus were elevated in the EMSI compared to the contralateral. After adjusting for marrow soft tissue composition using DECT, these measurements were no longer different between the two regions. By allowing for high-resolution, localized density analysis, HR-pQCT indicated that trabecular tissue mineral density was 9 mgHA/cm3 lower, while density of marrow soft tissues was 18 mgHA/cm3 higher, in the EMSI than the contralateral region, suggesting that EMSI have opposite effects on the measured density of trabecular bone and the underlying soft marrow. Thus, after an acute injury, altered composition of marrow soft tissues may artificially inflate overall measurements of bone density and apparent modulus obtained using standard QCT. This can be corrected by accounting for marrow soft tissue attenuation, either by using DECT-based density calibration or HR-pQCT microFE and measurements of local density of trabeculae.

Changes in macroelemental composition of red clover under influence of phytopathogenic fungi

The article discusses the issue of metabolic changes in the leaf tissues of red clover under the influence of the spectrum of phytopathogens, determined by means of X-ray microanalysis. In the course of the research, qualitative characteristics of metabolic changes under the influence of various phytopathogens were obtained, and quantitative parameters were determined for changes in the macroelement composition of clover plant tissues. All this makes it possible to obtain data on changes in plant metabolism, as well as changes in transport processes under the influence of phytopathogens.

Changes in the biochemical composition of broiler body tissues when feeding with Bacillus cereus probiotic and coumarin

The article presents the study results on the effect of probiotic (Bacillus cereus IP 5832) and coumarin on the chemical and amino acid composition of body tissues when fed to broiler chickens together with the main diet. According to the experimental results, an increase in the concentration of dry matter by 0.27% and crude fat by 0.75% was found in the liver of young animals from the I experimental group compared to the control. At the end of the experiment, the broilers from the control group were inferior in the protein amount in the liver of the experimental poultry by 0.46%, 2.69 (P ≤0.05) and 1.16%. A similar pattern was observed when studying pectoral muscles' chemical composition on the 16 and 29 day study period; the accumulation of dry matter and protein in the poultry's pectoral muscles from the III experimental group by 0.7 and 0.71%; 0.89 and 1.21% relative to the control was revealed. Feeding broilers with a basic diet plus coumarin contributed to the accumulation of essential amino acids in their liver: lysine – by 1.05%, phenylalanine – by 0.41% and leucine-isoleucine by 0.63% relative to the control.

Osteocytes and Estrogen Deficiency.

Postmenopausal osteoporosis reduces circulating estrogen levels, which leads to osteoclast resorption, bone loss, and fracture. This review addresses emerging evidence that osteoporosis is not simply a disease of bone loss but that mechanosensitive osteocytes that regulate both osteoclasts and osteoblasts are also impacted by estrogen deficiency. At the onset of estrogen deficiency, the osteocyte mechanical environment is altered, which coincides with temporal changes in bone tissue composition. The osteocyte microenvironment is also altered, apoptosis is more prevalent, and hypermineralization occurs. The mechanobiological responses of osteocytes are impaired under estrogen deficiency, which exacerbates osteocyte paracrine regulation of osteoclasts. Recent research reveals changes in osteocytes during estrogen deficiency that may play a critical role in the etiology of the disease. A paradigm change for osteoporosis therapy requires an advanced understanding of such changes to establish the efficacy of osteocyte-targeted therapies to inhibit resorption and secondary mineralization.

Recent Advances in Studying Age-Associated Lipids Alterations and Dietary Interventions in Mammals.

Lipids are involved in a broad spectrum of canonical biological functions, from energy supply and storage by triacylglycerols to membrane formation by sphingolipids, phospholipids and glycolipids. Because of this wide range of functions, there is an overlap between age-associated processes and lipid pathways. Lipidome analysis revealed age-related changes in the lipid composition of various tissues in mice and humans, which were also influenced by diet and gender. Some changes in the lipid profile can be linked to the onset of age-related neurodegenerative diseases like Alzheimer’s disease. Furthermore, the excessive accumulation of lipid storage organelles, lipid droplets, has significant implications for the development of inflammaging and non-communicable age-related diseases. Dietary interventions such as caloric restriction, time-restrictive eating, and lipid supplementation have been shown to improve pertinent health metrics or even extend life span and thus modulate aging processes.

Abstract 13602: Detection of Thermal Myocardial Injury Using the Microwave Return Loss Spectrum

Introduction: Thermocouples located inside conventional ablation catheters do not measure tissue temperature nor determine thermal lesion size during cardiac catheter ablation. Hypothesis: Progressive, thermally mediated changes in tissue composition can be detected by the return loss spectrum of a microwave antenna coupling to tissue in the microwave band. Results: Return loss (RL) exhibited characteristic changes in the 1.6 to 1.7 GHz band during heating (Panel A). Heating to a temperature lethal to the myocardium (50°C) reduced the RL amplitude of the sample from baseline by 346.7% (-10.80 ± 4.430 dB, p = 0.0055). Further temperature rise restituted RL amplitude back to approximately baseline values at 64°C to 70°C (Panel B). Conclusion: The pattern of RL amplitude change in the 1.6 - 1.7 GHz microwave band may be useful for detecting lethal thermal myocardial injury and prevent overheating. This observation may have applications for monitoring cardiac catheter ablation.

Quantitative analysis of the ACL and PCL using T1rho and T2 relaxation time mapping: an exploratory, cross-sectional comparison between OA and healthy control knees

BackgroundQuantitative magnetic resonance imaging (MRI) methods such as T1rho and T2 mapping are sensitive to changes in tissue composition, however their use in cruciate ligament assessment has been limited to studies of asymptomatic populations or patients with posterior cruciate ligament tears only. The aim of this preliminary study was to compare T1rho and T2 relaxation times of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) between subjects with mild-to-moderate knee osteoarthritis (OA) and healthy controls.MethodsA single knee of 15 patients with mild-to-moderate knee OA (Kellgren-Lawrence grades 2–3) and of 6 age-matched controls was imaged using a 3.0 T MRI. Three-dimensional (3D) fat-saturated spoiled gradient recalled-echo images were acquired for morphological assessment and T1ρ- and T2-prepared pseudo-steady-state 3D fast spin echo images for compositional assessment of the cruciate ligaments. Manual segmentation of whole ACL and PCL, as well as proximal / middle / distal thirds of both ligaments was carried out by two readers using ITK-SNAP and mean relaxation times were recorded. Variation between thirds of the ligament were assessed using repeated measures ANOVAs and differences in these variations between groups using a Kruskal-Wallis test. Inter- and intra-rater reliability were assessed using intraclass correlation coefficients (ICCs).ResultsIn OA knees, both T1rho and T2 values were significantly higher in the distal ACL when compared to the rest of the ligament with the greatest differences in T1rho (e.g. distal mean = 54.5 ms, proximal = 47.0 ms, p < 0.001). The variation of T2 values within the PCL was lower in OA knees (OA: distal vs middle vs proximal mean = 28.5 ms vs 29.1 ms vs 28.7 ms, p = 0.748; Control: distal vs middle vs proximal mean = 26.4 ms vs 32.7 ms vs 33.3 ms, p = 0.009). ICCs were excellent for the majority of variables.ConclusionT1rho and T2 mapping of the cruciate ligaments is feasible and reliable. Changes within ligaments associated with OA may not be homogeneous. This study is an important step forward in developing a non-invasive, radiological biomarker to assess the ligaments in diseased human populations in-vivo.

Compositional evaluation of lesion and parent bone in patients with juvenile osteochondritis dissecans of the knee using T2 * mapping.

Juvenile osteochondritis dissecans (JOCD) lesions contain cartilaginous, fibrous and osseous tissues which are difficult to distinguish with clinical, morphological magnetic resonance imaging (MRI). Quantitative T2 * mapping has earlier been used to evaluate microstructure and composition of all aforementioned tissues as well as bone mineral density. However, the ability of T2 * mapping to detect changes in tissue composition between different JOCD lesion regions, different disease stages, and between stable and unstable lesions has not been demonstrated. This study analyzed morphological and T2 * MRI data from 25 patients (median age, 12.1 years) with 34 JOCD-affected and 13 healthy knees. Each lesion was assigned a stage reflecting the natural history of JOCD, with stages I and IV representing early and healed lesion, respectively. T2 * values were evaluated within the progeny lesion, interface and parent bone of each lesion and in the control bone region. T2 * was negatively correlated with JOCD stage in progeny lesion (ρ = -0.871; p < 0.001) and interface regions (ρ = -0.649; p < 0.001). Stage IV progeny showed significantly lower T2 * than control bone (p = 0.028). T2 * was significantly lower in parent bone than in control bone of patients with stable lesions (p = 0.009), but not in patients with unstable lesions (p = 0.14). Clinical significance: T2 * mapping enables differentiation between different stages of JOCD and quantitative measurement of the ossification degree in progeny lesion and interface. The observed T2 * decrease in healed and stable lesions may indicate increased bone density as a result of the active repair process. T2 * mapping provides quantitative information about JOCD lesion composition.

Responsiveness of Subcutaneous Fat, Intermuscular Fat, and Muscle Anatomical Cross-Sectional Area of the Thigh to Longitudinal Body Weight Loss and Gain: Data from the Osteoarthritis Initiative (OAI)

Thigh subcutaneous (SCF) and intermuscular (IMF) fat have been associated with joint health and function. Here, we explore the (sex-specific) responsiveness of SCF, IMF, and muscle during longitudinal weight loss and gain, as well as the change in questionnaire-based and physical performance-based knee function measures. This exploratory study included 103 Osteoarthritis Initiative (OAI) participants, who displayed a ≥10% weight loss or gain between baseline (BL) and 2-year (Y2) follow-up (and maintained half of that weight loss until year 4) and had axial 3T magnetic resonance images (MRI) for measuring SCF, IMF, and muscle cross sectional areas (CSAs). The standardized response mean (SRM = mean divided by the standard deviation of the change) was used as a measure of responsiveness. A total of 52 OAI participants (73% women) displayed ≥10% weight loss, and 51 (67% women) ≥10% weight gain. Both SCF and IMF CSAs showed a significant decrease (mean change) with weight loss (SCF: −22%, SRM = −1.2; IMF: −15%, SRM = −0.7) and a significant increase with weight gain (SCF: +27%, SRM = 1.1; IMF: +21%, SRM = 0.6). Muscle CSAs showed significant changes during weight loss (extensor: −8.3%, SRM = −1.1; flexor: −7.2%, SRM = −1.0), but not during weight gain. Knee function measures were not relevantly associated with bidirectional changes in body weight. SCF and IMF CSAs are highly responsive to bidirectional weight change, whereas muscle CSAs were only responsive to weight loss. These findings highlight that MRI represents a sensitive tool for monitoring changes in thigh adipose tissue composition that may be applied during specific diet and/or exercise interventions.

Changes in Tissue Composition and Load Response After Transtibial Amputation Indicate Biomechanical Adaptation

Despite the potential for biomechanical conditioning with prosthetic use, the soft tissues of residual limbs following lower-limb amputation are vulnerable to damage. Imaging studies revealing morphological changes in these soft tissues have not distinguished between superficial and intramuscular adipose distribution, despite the recognition that intramuscular fat levels indicate reduced tolerance to mechanical loading. Furthermore, it is unclear how these changes may alter tissue tone and stiffness, which are key features in prosthetic socket design. This study was designed to compare the morphology and biomechanical response of limb tissues to mechanical loading in individuals with and without transtibial amputation, using magnetic resonance imaging in combination with tissue structural stiffness. The results revealed higher adipose infiltrating muscle in residual limbs than in intact limbs (residual: median 2.5% (range 0.2–8.9%); contralateral: 1.7% (0.1–5.1%); control: 0.9% (0.4–1.3%)), indicating muscle atrophy and adaptation post-amputation. The intramuscular adipose content correlated negatively with daily socket use, although there was no association with time post-amputation. Residual limbs were significantly stiffer than intact limbs at the patellar tendon site, which plays a key role in load transfer across the limb-prosthesis interface. The tissue changes following amputation have relevance in the clinical understanding of prosthetic socket design variables and soft tissue damage risk in this vulnerable group.