Mechanical Function Research Articles

Complications following total knee arthroplasty in patients with prior extensor mechanism dysfunction: A retrospective review

BackgroundExtensor mechanism disruption following total knee arthroplasty (TKA) is a rare, yet serious complication. While previous patellar abnormalities are a theoretical risk factor for this complication, there is a scarcity of literature describing the impact of prior extensor mechanism dysfunction (EMD) on this and other complications following TKA. In this study, we describe our institutional experience with complications following TKA after EMD. MethodsSixty-one knees that underwent total knee arthroplasty between April 2007 and April 2023 in patients with previous EMD were identified. Extensor mechanism dysfunction types included patellar fracture, patellar tendon rupture, patellar realignment surgery, previous patellar dislocation, and a chronic laterally tracking patella impacting extensor mechanism function. Primary outcomes included extensor mechanism failure, infection, dislocation, aseptic loosening, revision surgery, and stiffness requiring manipulation under anesthesia (MUA). ResultsA total of 61 knees, comprised of 53-patients, were included. There were complications witnessed in fifteen patients, leading to a 24.6 % overall complication rate. There was one extensor mechanism disruption in the form of a partial quadriceps tendon tear requiring repair. There was one patellar dislocation requiring reoperation. There were five superficial infections successfully treated non-operatively and four deep infections requiring reoperation. A total of nine reoperations were performed, four of which were revisions. Four patients underwent MUA due to severe post-operative stiffness. ConclusionIn this study, we found a high complication rate following TKA in patients with previous extensor mechanism dysfunction. There was one case of partial quadriceps tendon rupture requiring repair.

Alterations in Endogenous Stem Cell Populations in the Acute Phase of Blast-Induced Spinal Cord Injury.

Blast-induced spinal cord injury (bSCI) is prevalent among military populations and frequently leads to irreversible spinal cord tissue damage that manifests as sensorimotor and autonomic nervous system dysfunction. Clinical recovery from bSCI has been proven to be multifactorial, as it is heavily dependent on the function of numerous cell populations in the tissue environment, as well as extensive ongoing inflammatory processes. This varied recovery process is thought to be due to irreversible spinal cord damage after 72 hours post-injury. Stem cell therapy for spinal cord injuries has long been investigated due to these cells' proliferative nature, ability to enhance neuro-regeneration, neuroprotection, remyelination of axons, and modulation of the immune and inflammatory responses. Therefore, this study hypothesizes that the impaired function after injury is due to a lack of specific ectoderm and neural stem cell population activity at the injury site. This study aimed to elucidate changes in endogenous stem cell patterns by evaluating immunohistochemical staining densities of various stem cell markers using a preclinical thoracolumbar bSCI model. Analysis was performed 24-, 48-, and 72 hours following blast exposure. Behavior tests to assess sensory and mechanical functions were also performed. The following Cluster of differentiation (CD) markers CD105, CD45, CD133, and Vimentin, Nanog homebox (NANOG), and sex determining region Y HMG-box 2 (SOX2) positive cell populations were significantly elevated with trending increases in Octamer-binding transcription factor 4 (OCT4) in the thoracolumbar region of spinal cord tissue at 72 hours following bSCI (p < 0.05). Behavior analyses showed significant decreases in paw withdrawal thresholds in the hind limbs and changes in locomotion at 48- and 72 hours post-injury (p < 0.05). The significant increase in mesenchymal, pluripotent, and neural stem cell populations within the thoracolumbar region post-injury suggests that migratory patterns of stem cell populations are likely altered in response to bSCI. Behavioral deficits were consistent with those experienced by military personnel, such as increased pain-like behavior, reduced proprioception and coordination, and increased anxiety-like behavior post-bSCI, which underlines the translational capabilities of this model. While further research is vital to understand better the intrinsic and synergistic chemical and mechanical factors driving the migration of stem cells after traumatic injury, increased endogenous stem cell populations at the injury site indicate that stem cell-based treatments in patients suffering from bSCI could prove beneficial.

Recent Research on the Optimization of Interfacial Structure and Interfacial Interaction Mechanisms of Metal Matrix Composites: A Review

Interfaces in metal matrix composites (MMCs) are crucial in determining the mechanical properties and functionality of MMCs. This article reviews recent scientific advances and issues related to MMC interfaces from four different perspectives: interfacial structural design, interfacial defect control, thermodynamics and kinetics of interfacial reactions, and interfacial microstructure properties‐based numerical simulation. The influence of interfacial microstructural features on interfacial strength–toughness trade‐offs and their functionality is given special attention. The interfacial problem is still one of the main challenges to be solved in the composite system, which is mainly reflected in the following aspects: interfacial microstructure–deformation mechanisms in complex systems, precise control of interfacial defects and interfacial reaction products, and the efficient and cost‐effective application of numerical simulation techniques. The integrated computation and intelligent design (artificial intelligence) of composites through multiscale computational simulation with the guidance of “interface design‐property prediction” will be the key area of MMC interface research in the future.

Cytotoxicity and Microbiological Properties of Ceramic CAD/CAM Materials Subjected to Surface Treatment with Nanometric Copper Layer

The aim of this study is to present the characteristics and a comparison of four different commercial materials dedicated to the CAD/CAM technique in dentistry, all of which can be classified as ceramic materials. Its purpose is also to evaluate the impact of surface treatment on the cytotoxicity and microbiological properties of the materials. The CAD/CAM technique has a perpetually growing role in modern reconstructive dentistry. It requires a material’s possession of peculiar characteristics, such as mechanical resistance, durability, functionality (similar to natural tissues), good aesthetics and biocompatibility. To critically evaluate a biomaterial, both manufacturer claims and in vitro tests should be considered. Further steps of evaluation may include animal tests and clinical trials. There are certain attributes of biomaterials that may be modified by surface treatment that can be crucial to the clinical success of the material. The evaluated materials were Vita Suprinity (VITA-Zahnfabrik, Germany), Vita Mark II (VITA-Zahnfabrik, Germany), Celtra Duo (Dentsply Sirona, USA) and Empress Cad (Ivoclar Vivadent, Liechtenstein). They are available in the form of prefabricated blocks of various diameters and are popular among operators performing clinical procedures using CAD/CAM. Standardized blocks of each material were prepared. Half of them had their surface polished. Further, half of all the samples were covered by a nano-copper layer. The samples were evaluated for cytotoxicity, presented on a 0–4 scale, adhesion susceptibility and potential of forming a biofilm on their surface. Physicochemical properties such as the water contact angle (WCA) were evaluated for the tested materials. The influence of copper coating on cytotoxicity cannot be unequivocally stated or denied. Surface polishing did not affect the materials’ cytotoxicity, but it increased the WCA of all materials and, therefore, their hydrophobicity. Different degrees of adhesion ability and biofilm formation were dependent on the species of microorganisms and properties of the dental materials.

Calcium signaling in mitochondrial intermembrane space.

The mitochondrial intermembrane space (IMS) is a highly protected compartment, second only to the matrix. It is a crucial bridge, coordinating mitochondrial activities with cellular processes such as metabolites, protein, lipid, and ion exchange. This regulation influences signaling pathways for metabolic activities and cellular homeostasis. The IMS harbors various proteins critical for initiating apoptotic cascades and regulating reactive oxygen species production by controlling the respiratory chain. Calcium (Ca2+), a key intracellular secondary messenger, enter the mitochondrial matrix via the IMS, regulating mitochondrial bioenergetics, ATP production, modulating cell death pathways. IMS acts as a regulatory site for Ca2+ entry due to the presence of different Ca2+ sensors such as MICUs, solute carriers (SLCs); ion exchangers (LETM1/SCaMCs); S100A1, mitochondrial glycerol-3-phosphate dehydrogenase, and EFHD1, each with unique Ca2+ binding motifs and spatial localizations. This review primarily emphasizes the role of these IMS-localized Ca2+ sensors concerning their spatial localization, mechanism, and molecular functions. Additionally, we discuss how these sensors contribute to the progression and pathogenesis of various human health conditions and diseases.

Подзаконное регулирование предпринимательской деятельности в механизме обеспечения текущего равновесия экономической системы

The state economic policy is built on the basis of the set goals determined in accordance with the constitutional principles of the economic system. Maintaining a course towards achieving an equilibrium of the economic system, the state uses various tools. The system of constitutional principles of the economic system is reflected in the mechanism for ensuring its strategic equilibrium. However, attention should be paid to the functioning of the current equilibrium mechanism, which is an operational control tool. The article analyzes the possibilities of ensuring the equilibrium of the economic system by by-law regulation. It was concluded that in the ordinary mode of management, and especially in the event of extraordinary situations, it is by-law regulation that becomes the basis for maneuvering by the state in maintaining the equilibrium of the economic system.

Constrained Hamiltonian dynamics for electrons in magnetic field and additional forces besides the Lorentz force acting on electrons

Abstract We consider the forces acting on electrons in magnetic field including the constraints and a condition arising from quantum mechanics. The force is calculated as the electron mass, m e , multiplied by the total time-derivative of the velocity field evaluated using the quantum mechanical many-electron wave function. The velocity field includes a term of the Berry connection from the many-body wave function; thereby, quantum mechanical effects are included. It is shown that additional important forces besides the Lorentz force exist; they include the gradient of the electron velocity field kinetic energy, the gradient of the chemical potential, and the ‘force’ for producing topologically protected loop currents. These additional forces are shown to be important in superconductivity, electric current in metallic wires, and charging of capacitors.

Piezo1-driven mechanotransduction as a key regulator of cartilage degradation in early osteoarthritis.

Osteoarthritis (OA) is a prevalent degenerative disease characterized by pain and cartilage damage in its later stages, while early OA is marked by the loss of cartilage's mechanical function. Recent studies suggest that Piezo1, a mechanotransducer, may contribute to cartilage degradation under abnormal physical stress. This study investigates the mechanism by which Piezo1 mediates the loss of cartilage's mechanical properties. Using rat chondrocytes cultured in a 3D in vitro model, we found that fluid flow-induced physical stress activates constitutively expressed Piezo1, leading to increased catabolic activity and apoptosis, which, in turn, disrupts the matrix structure. Ex vivo cartilage experiments further demonstrated that the mechanical stress-induced loss of cartilage's physical properties (approximately 10% reduction in relaxation modulus) is mediated by Piezo1 and depends on cell viability. Notably, Piezo1 agonists alone did not alter the mechanical behavior of cartilage tissue. In vivo, using an OA rat model induced by anterior cruciate ligament transection, we observed cartilage integrity degradation and loss of mechanical properties, which were partially mitigated by Piezo1 inhibition. RNA sequencing revealed significant modulation of the PI3K signaling and matrix regulation pathways. Collectively, this study demonstrates that Piezo1-mediated catabolic activity in chondrocytes is a key driver of the loss of cartilage's mechanical function during the relaxation phase.

Comparative Study on Vascular Bundle Morphological Characteristics of Parts of Branches, Culms, and Rhizomes of Oligostachyum sulcatum

This study presents a comprehensive analysis of the vascular bundle morphology, tangential and radial diameters, and distribution frequency of different parts of Oligostachyum sulcatum, elucidating their structural and functional significance. Electron microscopy images revealed distinct vascular bundle characteristics in the different parts, including the vascular bundles in both parts of the rhizomes, the middle parts of the internodes, and the middle and inner parts of the branches, which were semi-open. The vascular bundles in the outer parts of both internodes and branches were semi-differentiated and undifferentiated. The vascular bundles in the inner parts of internodes were open. Statistical analysis showed significant variations in tangential and radial diameters among these parts, reflecting their diverse mechanical and physiological functions. The internodes exhibited the largest tangential and radial diameters, suggesting a critical role in mechanical support. In contrast, the branches had the smallest diameter, indicating that vascular bundle differentiation is influenced by growth conditions. The vascular bundle frequency was the highest in branches and the lowest in inside-sticks. This study provides theoretical references for the adaptive strategies and growth regulation mechanisms of O. sulcatum.

Confined Polyethylene Glycol Anchored in Kaolinite as High Ionic Conductivity Solid-State Electrolyte for Lithium Batteries.

Solid-state electrolytes (SSEs) have garnered significant attention as critical materials for enabling safer, energy-dense, and reversible electrochemical energy storage in batteries. Among the various types of solid electrolytes developed, composite polymer electrolytes (CPEs) have stood out as some of the most promising candidates due to their well-rounded performance. In this study, we choose polyethylene glycol (PEG) as the covalent grafting intercalant and lithium perchlorate as carrier source to prepare a fast lithium ion conductor, K-PEG-Li doped with clay-based active filler as a CPE. The CPE exhibits excellent lithium conduction (4.36 × 10-3 S cm-1 at 25 °C and 3.32 × 10-2 S cm-1 at 115 °C), great mechanical performance with good tensile strength (6.07 MPa) and toughness (strain 313%), and convincing flame-retardancy. These outstanding conducting and mechanical functionalities indicate that such a clay-based active filler doped composite polymer electrolyte will find promising application in solid-state lithium batteries.

Structural determinants of tendon multiscale mechanics and their sensitivity to mechanical stimulation during development in an embryonic chick model

There is an abrupt increase in the multiscale mechanical properties and load-bearing capabilities of tendon during development. While prior work has identified numerous changes that occur within the collagenous structure during this developmental period, the primary structural elements that give rise to this abrupt increase in mechanical functionality, and their mechanobiological sensitivity, remain unclear. To address this knowledge gap, we used a shear lag model along with ultrastructural imaging, biochemical/thermodynamic assays, and multiscale mechanical testing to investigate the dynamic structure-function relationships during late-stage embryonic chick development and to establish their sensitivity to mechanical stimulation. Mechanical testing and modeling suggested that the rapid increase in multiscale mechanics can be explained by increases in fibril length, intrafibrillar crosslinking, and fibril area fraction. To partially test this, we inhibited collagen crosslinking during development and observed a drastic reduction in multiscale mechanical behavior that was explained by a reduction in both fibril modulus and length. Using muscle paralysis to investigate mechanosensitivity, we observed a significantly impaired multiscale mechanical response despite minimal changes in fibril diameter and fibril area fraction. Additionally, the shear lag model found a trend toward lower fibril lengths with paralysis and experimental data found decreased crosslinking and fibril modulus values following flaccid paralysis. Together, these data suggest that both intrafibrillar crosslink formation and fibril elongation are critical to the formation of load-bearing capabilities in tenogenesis and are sensitive to mechanical loading. These findings provide critical insights into the biological and structural mechanisms that give rise to tensile load-bearing soft tissue. Statement of SignificanceDespite prior work investigating the structural and mechanical changes that occur during tendon development, there has not been a comprehensive analysis of how these simultaneous changes in structure and function are connected. In this study, we performed a comprehensive battery of mechanical and structural assessments of embryonic chick tendons and input these data into a shear lag model to estimate the individual importance of each structural change to the tendon mechanical properties. Additionally, we inhibited muscle activity in the embryos to evaluate the impact of mechanical stimulation on these evolving structure-function relationships during tendon development. These data provide insight into the primary structural elements that produce the tensile load-bearing capabilities of tendon, which will inform efforts to produce tissue engineered tendon replacements.

Life History Strategies Drive Meso-Scale Distribution Patterns in Coastal Benthic Macroinvertebrates.

The environment shapes the spatial distribution of species, but species also comprise suites of traits which may indicate their adaptability to a specific environment. This forms the basis of trait biogeography studies. We thus examined how a species distribution is not only influenced by its environment and traits, but by interactions among its traits. Trait information was collected for 150 intertidal macroinvertebrates along a 3000 km environmental and biogeographic gradient on the South African coast. This information was analysed, as functional entities (FEs) were species performing similar functions that have the same trait values and were further condensed into two trait domains (Reproduction and Lifestyle). We then defined Life History Strategies (LHS) as specific combinations of Lifestyle and Reproduction FEs. Seven combinations of Lifestyle and Reproduction formed LHS that dominated total biomass. Some of these LHS were ubiquitous, while others showed geographic patterns across our west-east environmental gradient. For Lifestyle, filter-feeders exhibited high abundances on the East (subtropical, oligotrophic) and West (cool-temperate, eutrophic) extremes of the biogeographic gradient, but differed between the two in size at reproductive maturity and larval development type. This similarity in functionality of feeding mechanism and mobility with different reproductive strategies suggests a trait trade-off (investment in one trait reduces resources for others) between the Reproduction and Lifestyle domains. Within the Reproduction domain, gonochoristic, annual planktotrophic reproduction was common across bioregions, reflecting spin-offs (investment in one trait facilitates another trait) among these traits. Gonochoristic investment in less frequent episodic reproduction is another trade-off, with investment in large size and delayed maturation being a trade-off for many reproductive cycles. Overall, although our data supports the habitat templet model (i.e., the importance of environmental drivers), it further indicates that species distribution patterns observed along the South African coast reflect strong trait interactions and biomass patterns related to their LHS.

Neuroendocrine transdifferentiation in human cancer: molecular mechanisms and therapeutic targets.

Neuroendocrine transdifferentiation (NEtD), also commonly referred to as lineage plasticity, emerges as an acquired resistance mechanism to molecular targeted therapies in multiple cancer types, predominately occurs in metastatic epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer treated with EGFR tyrosine kinase inhibitors and metastatic castration-resistant prostate cancer treated with androgen receptor targeting therapies. NEtD tumors are the lethal cancer histologic subtype with unfavorable prognosis and limited treatment. A comprehensive understanding of molecular mechanism underlying targeted-induced plasticity could greatly facilitate the development of novel therapies. In the past few years, increasingly elegant studies indicated that NEtD tumors share key the convergent genomic and phenotypic characteristics irrespective of their site of origin, but also embrace distinct change and function of molecular mechanisms. In this review, we provide a comprehensive overview of the current understanding of molecular mechanism in regulating the NEtD, including genetic alterations, DNA methylation, histone modifications, dysregulated noncoding RNA, lineage-specific transcription factors regulation, and other proteomic alterations. We also provide the current management of targeted therapies in clinical and preclinical practice.

Regulatory effects of the p38 mitogen-activated protein kinase-myosin light chain kinase pathway on the intestinal epithelial mechanical barrier and the mechanism of modified Pulsatilla decoction in the treatment of ulcerative colitis.

To investigate the mechanism of the protective effect of modified Pulsatilla decoction (, MPD) on the mechanical barrier of the ulcerative colitis (UC) intestinal epithelium in vitro and in vivo. We established an intestinal epithelial crypt cell line-6 cell barrier injury model by using lipopolysaccharide (LPS). The model was then treated with p38 mitogen-activated protein kinase-myosin light chain kinase (p38MAPK-MLCK) pathway inhibitors, p38MAPK-MLCK pathway silencing genes (si-p38MAPK, si-NF-κB, and si-MLCK), and MPD respectively. Transepithelial electronic resistance (TEER) measurements and permeability assays were performed to assess barrier function. Immunofluorescence staining of tight junctions (TJ) was performed. In in vivo experiment, dextran sodium sulfate-induced colitis rat model was conducted to evaluate the effect of MPD and mesalazine on UC. The rats were scored using the disease activity index based on their clinical symptoms. Transmission electron microscopy and hematoxylin-eosin staining were used to examine morphological changes in UC rats. Western blotting and real-time quantitative polymerase chain reaction were performed to examine the gene and protein expression of significant differential molecules. In in vitro study, LPS-induced intestinal barrier dysfunction was inhibited by p38MAPK-MLCK pathway inhibitors and p38MAPK-MLCK pathway gene silencing. Silencing of p38MAPK-MLCK pathway genes decreased TJ expression. MPD treatment partly restored the LPS-induced decreased in TEER and increase in permeability. MPD increased the gene and protein expression of TJ, while down-regulated the LPS-induced high expression of p-p38MAPK and p-MLC. In UC model rats, MPD could ameliorate body weight loss and disease activity index, relieve colonic pathology, up-regulate TJ expression as well as decrease the expression of p-p38MAPK and p-MLC in UC rat colonic mucosal tissue. The p38MAPK-MLCK signaling pathway can affect mechanical barrier function and TJ expression in the intestinal epithelium. MPD restores TJ expression and attenuates intestinal epithelial barrier damage by suppressing the p38MAPK-MLCK pathway.

Water-soluble polysaccharides extracted from Enteromorpha prolifera/PVA composite film functionalized as ε-polylysine with improved mechanical and antibacterial properties

The issue of environmental protection has received sustained and widespread attention. In order to reduce environmental pollution related to traditional plastics, it is an incessant demand to design novel environment-friendly food packaging materials with excellent performance. Sulfated polysaccharide extracted from the “green tide” marine pollution Enteromorpha prolifera (SPE) has been innovatively transformed into a film-forming material for better utilization. The insufficient mechanical properties and limited functionalities, however, hinder its wide application. In this study, polyvinyl alcohol (PVA) was blended to enhance its mechanical properties and ε-polylysine (ε-PL) was incorporated to endow it with antimicrobial performance. A novel and biodegradable film composed of SPE, PVA, and ε-PL was fabricated by casting method. We further determined the physicochemical properties of composited films. Mechanical performance test revealed the tensile strength of SPE-PVA-PL films increased from 5.56 MPa to 6.65 MPa and the E% increased from 128.8 % to 246.9 % compared with that of SPE-PVA films. Antimicrobial tests showed the excellent antibacterial activity of SPE-PVA-PL films against representative microbial species, Staphylococcus aureus and Escherichia coli. The results of this study suggested that the SPE-based composite film has the potential to be used as a potential food packaging and wound dressing materials.

Microstructural Regulation of Co TCPP by Acetylene Black: Enhanced Electrochemical Performance for Wearable Supercapacitors

Abstract With the rapid development of wearable devices, flexible supercapacitors have become an important energy storage prototype due to their inherent flexibility and high power density. Two-dimensional metal-organic framework (2D MOF) nanosheets are widely used in energy storage systems due to their structural tunability and anisotropy. However, their high surface energy tends to lead to aggregation, which results in poor dispersion and rheology of formulated inks and inhomogeneity of printed electrodes. Existing methods involve surface modulation by capped organic ligands, yet ignore the inherent conductivity and stability of MOFs. To overcome the low conductivity and aggregation problems of 2D MOFs, we adopted a novel approach combining mechanical intercalation and surface functionalization of cobalt-based porphyrin frameworks (Co TCPP) with acetylene black (AB). The unique microstructure of the composite material leads to favorable changes in the electronic properties of AB, which reduces the overall internal resistance and promotes rapid charge transfer. For this purpose, we have prepared micro-supercapacitors (MSCs) using dispensing printing technology. This integrated material has excellent mechanical flexibility and maintains 92% specific capacitance even under extreme bending and torsion. This study highlights the potential of integrating 2D MOFs with carbon-based materials (e.g., acetylene black) for a variety of applications in wearable electronics, and provides a guiding scheme for future micro-modulation of 2D MOFs using conductive materials.

Enhancement and mechanism of mechanical properties and functionalities of polyacrylamide/polyacrylic acid hydrogels by 1D and 2D nanocarbon

Highly flexible hydrogels are widely used in fields such as agriculture, drug delivery, and tissue engineering. However, the simultaneous integration of excellent mechanical properties, swelling properties, and high electrical conductivity into a hydrogel is still a great challenge. This work introduces 1D tubular multi-walled carbon nanotubes (MWCNTs) and 2D layered graphene oxide (GO) into polyacrylamide/poly-acrylic acid (PAM/PAA) hydrogels. The high specific surface area and oxygen-containing groups of GO contribute to excellent mechanical properties and water absorption of the PAM/PAA hydrogels, but the conductivity is poorly affected due to the presence of defects on GO surface. However, MWCNTs with large aspect ratios benefit to form continuous conductive paths in PAM/PAA hydrogels which further improves conductivity of the hydrogels. MWCNTs are entangled with PAM/PAA molecular chains to form a dense three-dimensional (3D) network structure, and this special structure improves the water absorption of PAM/PAA hydrogels by 3.7 g g−1. What’s more, the MWCNTs/PAM/PAA hydrogel not only provides excellent mechanical properties (compressive strength up to 2.7 MPa), but also has high conductivity (2.3 S m−1). In particular, a strain sensor based on MWCNTs/PAM/PAA hydrogel exhibits exceptional sensitivity (gauge factor = 3.9 at 230–300 % strain) with a rapid response (200 ms) over a wide strain range (50 ∼ 200 %) which enables the ability to precisely and reliably monitor human motion. Therefore, the work provides a new insight into the design of multifunctional hydrogels with application on anatomical water plugging, electronic skin, and biosensors.

Myocardial mechanical function measured by cardiac magnetic resonance in patients with heart failure

AimStrain analysis offers a valuable tool to assess myocardial mechanics, allowing for the detection of impairments in heart function. This study aims to evaluate the pattern of myocardial strain in patients with heart failure (HF). MethodsIn the present study, myocardial strain was measured by cardiac magnetic resonance imaging feature tracking in 35 control subjects without HF and 195 HF patients. The HF patients were further categorized as HF with preserved ejection fraction (HFpEF, n=80), with mid-range ejection fraction (HFmrEF, n=34), and with reduced ejection fraction (HFrEF, n=81). Additionally, quantitative tissue evaluation parameters, including native T1 relaxation time and extracellular volume (ECV), were examined. ResultsCompared to controls, patients in all HF groups (HFpEF, HFmrEF, and HFrEF) demonstrated impaired left ventricular (LV) strains and systolic and diastolic strain rates in all three directions (radial, circumferential, and longitudinal) (p < 0.05 for all). LV strains also showed significant correlations with left ventricular ejection fraction and brain natriuretic peptide levels (p < 0.001 for all). Notably, septal contraction was significantly affected in HFpEF compared to controls. While LV torsion was slightly increased in HFpEF, it was decreased in HFrEF. Native T1 relaxation times and ECV fractions were significantly higher in HFrEF compared to HFpEF (p < 0.05). Overall, myocardial strain parameters demonstrated good performance in differentiating HF categories. ConclusionsThe myocardial strain impairments exhibit a spectrum of severity in patients with HFpEF, HFmrEF, and HFrEF compared to controls. Assessment of myocardial mechanics using strain analysis may offer a clinically useful tool for monitoring the progression of systolic and diastolic dysfunction in HF patients.

Submaximal eccentric resistance training increases serial sarcomere number and improves dynamic muscle performance in old rats.

The age-related loss of muscle mass is partly accounted for by the loss of sarcomeres in series, contributing to declines in muscle mechanical performance. Resistance training biased to eccentric contractions increases serial sarcomere number (SSN) in young muscle, however, maximal eccentric training in old rats previously did not alter SSN and worsened performance. A submaximal eccentric training stimulus may be more conducive to adaptation for aged muscle. The purpose of this study was to assess whether submaximal eccentric training can increase SSN and improve mechanical function in old rats. Twelve 32-month-old male F344/BN rats completed 4 weeks of submaximal (60% maximum) eccentric plantar-flexion training 3 days/week. Pre- and post-training, we assessed in-vivo maximum isometric torque at a stretched and neutral ankle angle, the passive torque-angle relationship, and the isotonic torque-velocity-power relationship. The soleus and medial gastrocnemius (MG) were harvested for SSN measurements via laser diffraction, with the untrained leg as a control. SSN increased 11% and 8% in the soleus and MG, respectively. Training also shifted optimal torque production towards longer muscle lengths, reduced passive torque 42%, and increased peak isotonic power 23%. Submaximal eccentric training was beneficial for aged muscle adaptations, increasing SSN, reducing muscle passive tension, and improving dynamic contractile performance.

Multifunctional characterization of cement-Sargassum composites for application as bioconstruction materials

Utilizing solid waste biomass developing of construction materials presents an environmental mitigation opportunity by gradually replacing conventional materials that generate diverse ecological impacts. This approach aligns with circular economy and green chemistry principles, promoting the creation of sustainable materials. This research analyzes the use of brown algae from the Sargassum genus for bioconstruction applications through its mix with Portland cement. The mass influx of pelagic Sargassum species onto Caribbean beaches since 2011 has significantly impacted the environment, economy, and human health. The valorization of Sargassum is crucial for effective management and impact reduction. The study encompasses four key stages: (a) collection and processing of the algae, (b) development of a construction material composed of Portland cement and Sargassum at concentrations of 5 wt.% and 7.5 wt.%, (c) multifunctional characterization of the composite material, encompassing physical chemistry and thermal, optical and mechanical properties, and (d) an economic-environmental evaluation of using the construction material for housing in the Mexican Caribbean to enhance thermal insulation and reduce electric energy consumption associated with air conditioning. Test specimens of the composite material reveal compressive strength ranging between 78 and 347 kg/cm2, solar spectrum absorbance between 54% and 70%, and thermal conductivity between 0.65 and 1 W/mK. The economic-environmental analysis indicates that employing the construction material in 5% of households in the state of Quintana Roo, Mexico, could lead to annual reductions in energy consumption of approximately 67 GWh, with savings exceeding US$33,000, and environmental yearly mitigation equivalent to 4.1 TnNOx, 5.2 TnCH4, and 33,262 TnCO2. These results suggest promising prospects for incorporating Sargassum into construction materials, offering potential environmental and economic benefits. The composite material demonstrates optical, thermal, and mechanical functionality.