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1.
Proc Natl Acad Sci U S A ; 121(29): e2320769121, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38990949

RESUMO

Cytokinesis is the process where the mother cell's cytoplasm separates into daughter cells. This is driven by an actomyosin contractile ring that produces cortical contractility and drives cleavage furrow ingression, resulting in the formation of a thin intercellular bridge. While cytoskeletal reorganization during cytokinesis has been extensively studied, less is known about the spatiotemporal dynamics of the plasma membrane. Here, we image and model plasma membrane lipid and protein dynamics on the cell surface during leukemia cell cytokinesis. We reveal an extensive accumulation and folding of the plasma membrane at the cleavage furrow and the intercellular bridge, accompanied by a depletion and unfolding of the plasma membrane at the cell poles. These membrane dynamics are caused by two actomyosin-driven biophysical mechanisms: the radial constriction of the cleavage furrow causes local compression of the apparent cell surface area and accumulation of the plasma membrane at the furrow, while actomyosin cortical flows drag the plasma membrane toward the cell division plane as the furrow ingresses. The magnitude of these effects depends on the plasma membrane fluidity, cortex adhesion, and cortical contractility. Overall, our work reveals cell-intrinsic mechanical regulation of plasma membrane accumulation at the cleavage furrow that is likely to generate localized differences in membrane tension across the cytokinetic cell. This may locally alter endocytosis, exocytosis, and mechanotransduction, while also serving as a self-protecting mechanism against cytokinesis failures that arise from high membrane tension at the intercellular bridge.


Assuntos
Actomiosina , Membrana Celular , Citocinese , Citocinese/fisiologia , Membrana Celular/metabolismo , Humanos , Actomiosina/metabolismo
2.
Cureus ; 16(5): e61315, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38947730

RESUMO

In this study, we propose a method for navigating the choice of treatment for stress urinary incontinence (SUI) and urgency urinary incontinence (UUI) using graph theory in discrete mathematics. Our previous study accumulated data from 150 patients who underwent tension-free vaginal tape (TVT), transobturator tape (TOT), and vaginal non-ablation Erbium YAG laser (VEL) surgeries between 2014 and 2016. Network diagrams were created using this data. The treatments TVT, TOT, and VEL, along with patient characteristics (1-hour pad test: 1-hrPadTest, Overactive Bladder Symptom Score: OABSS), were represented as nodes and edges in the network diagram. We then employed a heuristic function to select the optimal treatment method for the patients with SUI and UUI. This process enables medical professionals to easily navigate the data for patients with both SUI and UUI concerns by calculating the shortest path connecting the 1-hrPadTest and OABSS. These results, which are consistent with those of previous studies, suggest that VEL is the optimal treatment. Unlike previous studies that employed statistical knowledge that is challenging for patients to understand, our study aids patients in visually comprehending and developing a customized treatment plan. This approach introduces a novel perspective for clinical decision-making in the treatment of urinary incontinence. To the best of our knowledge, this is the first study to apply discrete mathematics to patient decision-making for urinary incontinence treatment.

3.
ACS Sens ; 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38968930

RESUMO

DNA-based tension sensors have innovated the imaging and calibration of mechanosensitive receptor-transmitted molecular forces, such as integrin tensions. However, these sensors mainly serve as binary reporters, only indicating if molecular forces exceed one predefined threshold. Here, we have developed tandem tension sensor (TTS), which comprises two consecutive force-sensing units, each with unique force detection thresholds and distinct fluorescence spectra, thereby enabling the quantification of molecular forces with dual reference levels. With TTS, we revealed that vinculin is not required for transmitting integrin tensions at approximately 10 pN (piconewtons) but is essential for elevating integrin tensions beyond 20 pN in focal adhesions (FAs). Such high tensions have emerged during the early stage of FA formation. TTS also successfully detected changes in integrin tensions in response to disrupted actin formation, inhibited myosin activity, and tuned substrate elasticity. We also applied TTS to examine integrin tensions in platelets and revealed two force regimes, with integrin tensions surpassing 20 pN at cell central regions and 13-20 pN integrin tensions at the cell edge. Overall, TTS, especially the construct consisting of a hairpin DNA (13 pN opening force) and a shearing DNA (20 pN opening force), stands as a valuable tool for the quantification of receptor-transmitted molecular forces within living cells.

4.
Cell Mol Life Sci ; 81(1): 291, 2024 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-38970683

RESUMO

Plakophilin 4 (PKP4) is a component of cell-cell junctions that regulates intercellular adhesion and Rho-signaling during cytokinesis with an unknown function during epidermal differentiation. Here we show that keratinocytes lacking PKP4 fail to develop a cortical actin ring, preventing adherens junction maturation and generation of tissue tension. Instead, PKP4-depleted cells display increased stress fibers. PKP4-dependent RhoA localization at AJs was required to activate a RhoA-ROCK2-MLCK-MLC2 axis and organize actin into a cortical ring. AJ-associated PKP4 provided a scaffold for the Rho activator ARHGEF2 and the RhoA effectors MLCK and MLC2, facilitating the spatio-temporal activation of RhoA signaling at cell junctions to allow cortical ring formation and actomyosin contraction. In contrast, association of PKP4 with the Rho suppressor ARHGAP23 reduced ARHGAP23 binding to RhoA which prevented RhoA activation in the cytoplasm and stress fiber formation. These data identify PKP4 as an AJ component that transduces mechanical signals into cytoskeletal organization.


Assuntos
Actinas , Junções Aderentes , Placofilinas , Proteína rhoA de Ligação ao GTP , Placofilinas/metabolismo , Placofilinas/genética , Proteína rhoA de Ligação ao GTP/metabolismo , Junções Aderentes/metabolismo , Humanos , Actinas/metabolismo , Queratinócitos/metabolismo , Queratinócitos/citologia , Proteínas Ativadoras de GTPase/metabolismo , Proteínas Ativadoras de GTPase/genética , Quinases Associadas a rho/metabolismo , Quinases Associadas a rho/genética , Transdução de Sinais , Fibras de Estresse/metabolismo , Células Cultivadas , Animais
5.
J Exp Orthop ; 11(3): e12088, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38974053

RESUMO

Purpose: This paper investigates the biomechanical benefits of using hybrid constructs that combine cannulated screws with tension band wiring (TBW) cerclage compared to cannulated screws with anterior Variable Angle locking neutralisation plates (VA LNP). These enhancements can bear heavier loads and maintain the repaired patella's integrity, in contrast to traditional methods. Method: Eighteen fresh-frozen human cadaver patellae were carefully fractured transversely at their midpoints using a saw. They were then divided into two groups of nine for subsequent utilisation. Fixation methods included Cannulated Screw Fixation added with either TBW or VA LNP Fixation Technique. Cyclic loading simulations (500 cycles) were conducted to mimic knee motion, tracking fracture displacement with Optotrak. After that, the constructs were secured over a servo-hydraulic testing machine to determine the load-to-failure on axial mode. Results: The average fracture displacement for the anterior neutralisation plate group was 0.09 ± 0.12 mm, compared to 0.77 ± 0.54 mm for the tension band wiring with cannulated screw group after 500 cyclic loading. This result is statistically significant (p = 0.004). The anterior neutralisation plate group exhibited a mean load-to-failure of 1359 ± 21.53 N, whereas the tension band wiring group showed 780.1 ± 22.62 N, resulting in a significant difference between the groups (p = 0.007). Conclusion: This research highlights the superior biomechanical advantage of VA LNP over TBW for treating simple transverse patella fractures with two cannulated screws. It also highlights how the TBW is still a valuable option considering the load-to-failure limit. Level of Evidence: Not Applicable.

6.
Macromol Rapid Commun ; : e2400438, 2024 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-38980977

RESUMO

Liquid marbles (LMs) with a cubic shape are created by using various vinyl monomers as an inner liquid and polymer plates with mm size as a stabilizer. The relationship between the surface tension of the vinyl monomers and formability of the LMs is investigated. LMs can be fabricated using vinyl monomers with surface tensions of 42.7-40.3 mN m-1. The cubic polymer particles are successively synthesized via free-radical polymerizations by irradiation of the cubic LMs with UV light in a solvent-free manner. In addition, controlling the number of polymer plates per one LM, the shape of the plate or the coalescence of the LMs can lead to production of polymer particles with desired forms (e.g., Platonic and rectangular solids) that correspond to the shapes of the original LMs.

7.
Artigo em Inglês | MEDLINE | ID: mdl-38984538

RESUMO

Tissue tension encompasses the mechanical forces exerted on solid tissues within animal bodies, originating from various sources such as cellular contractility, interactions with neighboring cells and the extracellular matrix. Emerging evidence indicates that an imbalance in such forces can influence structural organization, homeostasis, and potentially contribute to disease. For instance, heightened tissue tension can impede apical cell extrusion, leading to the retention of apoptotic or transformed cells. In this study, we investigate the potential role of adenomatous polyposis coli (APC) in modulating tissue tension. Our findings reveal that expression of an APC truncation mutant elevates epithelial tension via the RhoA/ROCK pathway. This elevation induces morphological alterations and hampers apoptotic cell extrusion in cultured epithelial cells and organoids, both of which could be mitigated by pharmacologically restoring the tissue tension. This raises the possibility that APC mutations may exert pathogenetic effects by altering tissue mechanics.

8.
Heliyon ; 10(12): e32491, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38952357

RESUMO

Purpose: To investigate the physical properties of commercially available multipurpose soft contact lens solutions in Ghana. Methods: pH (Kelilong ICL-099 pH meter, China), osmolality (OSMOMAT 3000, GONOTEC, Germany), surface tension (Sigma 700 Tensiometer, Sweden), and viscosity (CFOC-200 Viscometer, Cannon Company, USA) of various soft contact lens multipurpose solutions (MPS) were measured in triplicates at room temperature. Viscosity measurements were also taken at 34 °C ocular surface temperature. The solutions examined were Opti-Free Replenish (OFR), Trufresh (TF), Avizor (AV), Freshlook (FL), and Refresh (RF). Results: Several solutions were largely hypo-osmotic in the range of 108-231 mOsm/kg, the exception being Avizor, which had osmolality values that were closer to human tears (301 ± 0.58 mOsm/kg). The range of pH values of the solutions (6.33-8.24, mean (SD) = 7.53 ± 0.18) fell within the reported tolerable range for the ocular surface (6.20-9.00). Surface tension values ranged from 35.86 to 42.27 mNm with a mean of 38.49 ± 2.32 mNm. The average viscosity of most solutions at room temperature (25 °C) was 1.44 ± 0.49 cP with a range of 1.04-2.15 cP. Significantly lower values ranging from 0.79 to 1.58 cP were obtained at ocular surface temperature (34 °C), p = 0.0001). Conclusions: The physical properties of many of the solutions used as MPS in Ghana are markedly variable. Nevertheless, pH, surface tension, and viscosity fall within the acceptable limits of ocular physiological tolerance; except for osmolality, which majority were outside the reported tolerable range for the ocular surface. This information may partly explain the reason some patients exhibit strong preferences for certain care systems and should aid clinical decision-making when prescribing eye care systems to patients.

9.
Am J Ophthalmol ; 2024 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-38977152

RESUMO

PURPOSE: To identify the role of systemic arterial stiffness and choroidal microvascular insufficiency on structural progression of normal-tension glaucoma (NTG). DESIGN: Retrospective cohort study. METHODS: A total of 107 early NTG eyes of 88 patients, who underwent pulse wave velocity (PWV) measurements and optical coherence tomography (OCT) angiography (OCT-A) at baseline, were categorized depending on the presence of peripapillary choroidal microvasculature dropout (MvD) and PWV. Differences in glaucomatous progression were analyzed. Structural progression rates were determined using the trend-based analysis of cirrus OCT. RESULTS: Thirty-two eyes displayed choroidal MvD (62.7 (95% CI 58.4-67.0) years old, 53.6% males), and 70 eyes did not show any MvD (59.9 (95% CI 57.1-62.6) years old, 53.3% males) at baseline. Patients were followed for 48.4 (95% CI 40.0-56.8) months. When they were further divided based on PWV (high PWV≥1400cm/sec), those with choroidal MvD and high PWV showed significantly faster thinning in macular ganglion cell-inner plexiform layer (GCIPL; P=0.023). In comparison to those with low PWV and no MvD, eyes with high PWV and MvD in the peripapillary area were likely to show fast structural progression (≤-1.2 µm/year) in the macular GCIPL by odds of 6.019 (95% CI 1.619-38.531, P=0.025). CONCLUSIONS: In NTG eyes, GCIPL thinning was faster when choroidal MvD and high systemic arterial stiffness were present. The simultaneous presence of regional and systemic vascular insufficiency may be associated with rapid glaucoma structural progression in eyes with low baseline intraocular pressure.

10.
Surg Endosc ; 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38977498

RESUMO

BACKGROUND: Excessive tension at the anastomosis contributes to anastomotic leakage (AL) in low anterior resection (LAR). However, the specific tension has not been measured. We assessed whether "Bridging," characterized by the proximal colon resembling a suspension bridge above the pelvic floor, is a significant risk factor for AL following LAR for rectal cancer. METHODS: This retrospective study reviewed the medical records and laparoscopic videos of 102 patients who underwent laparoscopic LAR using the double stapling technique at Yachiyo Hospital between January 2014 and December 2023. Patients were classified based on whether they had Bridging (tight or sagging) or were in a Resting state of the proximal colon, and the association between Bridging and AL was examined. RESULTS: AL occurred in 31.3% of the Tight Bridging group, 20% of the Sagging Bridging group, and 2.2% of the Resting group (P = 0.002). The incidence of AL was significantly higher in patients with Bridging than in those without (23.2% vs. 2.2%, P = 0.003). Multivariate analysis revealed that Bridging is an independent risk factor for AL (odds ratio = 6.97; 95% confidence interval: 1.45-33.6; P = 0.016). CONCLUSIONS: The presence of Bridging is a significant risk factor for AL following LAR for rectal cancer, suggesting the need for implementing preventive measures in patients with this condition.

11.
J Orthop ; 57: 35-39, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38957798

RESUMO

Aims and objectives: Genu recurvatum deformity after treatment of leg-length discrepancy (LLD) with tension-band plating is a recognized, but poorly described phenomenon in medical literature. The aim of this study was to evaluate clinical and radiological features of patients treated with tension-band plating for LLD assessing the development of a recurvatum deformity and its relationship to plate and screw disposition in a transversal plane, thus attempting to establish optimal plate positioning. Materials and methods: Retrospective study of children with LLD treated with tension-band plating. Primary endpoints were clinical and radiological knee recurvatum and anterior and posterior physeal areas measured drawing a line spanning from the lateral to the medial tension-band plates in the transverse plane using volumetric magnetic resonance imaging (vMRI). These findings were compared between patients with and without knee recurvatum. Results: Twelve children (mean age 11.7 years) were included. Average follow-up was 2.6 years (1.5-5.0). Tension-band plating led to a significant reduction in LLD (mean, 15 mm). Six patients (50 %) developed clinical genu recurvatum (mean, 22°). According to vMRI, patients with genu recurvatum had a larger posterior to anterior physeal area ratio in both distal femur (1.6 versus 0.9, p < 0.05) and proximal tibial physes (2.2 versus 1.0, p < 0.05). Conclusion: The optimal position of the tension-band plates in distal femoral and proximal tibial physes should be in a point where a posterior to anterior physeal areas ratio is around 1.0, so as to achieve an even distribution of the physeal areas in the multidimensional physeal transverse plane. This point anatomically corresponds in the sagittal X-ray view to an imaginary line located just anterior to the posterior diaphyseal cortical bone on a true lateral radiograph for both femur and tibia.

12.
Cell Rep Methods ; : 100815, 2024 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-38986612

RESUMO

The ability of cells to sense and respond to mechanical forces is critical in many physiological and pathological processes. However, determining the mechanisms by which forces affect protein function inside cells remains challenging. Motivated by in vitro demonstrations of fluorescent proteins (FPs) undergoing reversible mechanical switching of fluorescence, we investigated whether force-sensitive changes in FP function could be visualized in cells. Guided by a computational model of FP mechanical switching, we develop a formalism for its detection in Förster resonance energy transfer (FRET)-based biosensors and demonstrate its occurrence in cellulo within a synthetic actin crosslinker and the mechanical linker protein vinculin. We find that in cellulo mechanical switching is reversible and altered by manipulation of cell force generation, external stiffness, and force-sensitive bond dynamics of the biosensor. This work describes a framework for assessing FP mechanical stability and provides a means of probing force-sensitive protein function inside cells.

13.
J Headache Pain ; 25(1): 111, 2024 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-38982389

RESUMO

BACKGROUND: Pediatric headache is an increasing medical problem that has adverse effects on children's quality of life, academic performance, and social functioning. Children with primary headaches exhibit enhanced sensory sensitivity compared to their healthy peers. However, comprehensive investigations including multimodal sensory sensitivity assessment are lacking. This study aimed to compare sensory sensitivity of children with primary headaches with their healthy peers across multiple sensory domains. METHODS: The study included 172 participants aged 6 to 17 years (M = 13.09, SD = 3.02 years; 120 girls). Of these 80 participants were patients with migraine, 23 were patients with tension-type headache, and 69 were healthy controls. The following sensory measures were obtained: Mechanical Detection Threshold (MDT), Mechanical Pain Threshold (MPT), Mechanical Pain Sensitivity (MPS), detection and pain threshold for Transcutaneous Electrical Nerve Stimulation (TENS), olfactory and intranasal trigeminal detection threshold, and odor identification ability. Sensory sensitivity was compared between groups with a series of Kruskal-Wallis tests. Binomial regression models were used to compare the relative utility of sensory sensitivity measures in classifying participants into patients and healthy controls, as well as into patients with migraine and tension-type headache. RESULTS: Patients with migraine had lower MPT measured at the forearm than patients with tension-type headaches and healthy controls. MPS was higher in patients with migraine than in healthy controls. All patients with headaches had lower detection threshold of TENS and higher olfactory sensitivity. Healthy controls showed increased intranasal trigeminal sensitivity. Scores in MPS, TENS, and olfactory and trigeminal thresholds were significantly predicting presence of primary headaches. Additionally, scores in MPT, olfactory and trigeminal threshold were positive predictors of type of headache. CONCLUSIONS: Children with primary headaches exhibit different sensory profiles than healthy controls. The obtained results suggest presence of increased overall, multimodal sensitivity in children with primary headaches, what may negatively impact daily functioning and contribute to further pain chronification. TRIAL REGISTRATION: The study was registered in the German Registry of Clinical Trials (DRKS) DRKS00021062.


Assuntos
Transtornos de Enxaqueca , Limiar da Dor , Cefaleia do Tipo Tensional , Humanos , Adolescente , Feminino , Masculino , Criança , Cefaleia do Tipo Tensional/fisiopatologia , Cefaleia do Tipo Tensional/diagnóstico , Transtornos de Enxaqueca/fisiopatologia , Transtornos de Enxaqueca/diagnóstico , Limiar da Dor/fisiologia , Limiar Sensorial/fisiologia , Transtornos da Cefaleia Primários/fisiopatologia , Transtornos da Cefaleia Primários/diagnóstico
14.
Intensive Care Med Exp ; 12(1): 61, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38976096

RESUMO

PURPOSE: Currently, there is no marker of efficacy of red blood cell (RBC) transfusion. This study describes the impact of RBC transfusion on mitochondrial oxygen tension (mitoPO2) and mitochondrial oxygen consumption (mitoVO2) in critically ill patients with anemia. METHODS: Critically ill patients with a hemoglobin concentration < 10 g/dL, for whom a single RBC unit had been ordered, were included. MitoPO2 was measured with the COMET device immediately before RBC transfusion, 0.5 h, 1 h, 3 h, and 24 h after RBC transfusion. MitoVO2 was calculated from dynamic mitoPO2 measurements during cessation of local oxygen supply. RESULTS: Sixty-three patients participated, median age 64.0 (interquartile range (IQR) 52.3-72.8) years, median hemoglobin concentration before transfusion 7.4 (IQR 7.1-7.7) g/dL. Median mitoPO2 values were 55.0 (IQR 49.6-63.0) mmHg before RBC transfusion, 51.0 (IQR 41.5-61.2) directly after and 67.3 (IQR 41.6-83.7) at 24 h after RBC transfusion. Median mitoVO2 values were 3.3 (IQR 2.1-5.9) mmHg/s before RBC transfusion, 3.7 (IQR 2.0-5.1) mmHg/s directly after, and 3.1 (IQR 2.5-4.8) mmHg/s 24 h after RBC transfusion. In the higher Hb concentration group (> 7 g/dL), we saw a dissociation of the effect of RBC transfusion on mitoPO2 versus on mitoVO2 values. MitoPO2 and mitoVO2 values were not associated with commonly used parameters of tissue perfusion and oxygenation. CONCLUSION: RBC transfusion did not alter mitoPO2 and mitoVO2 in critically ill patients with anemia. MitoPO2 and mitoVO2 values were not notably associated with Hb concentrations, parameters of severity of illness and markers of tissue perfusion or oxygenation. Given the high baseline value, it cannot be excluded nor confirmed whether RBC can improve low mitoPO2. Trial registration number NCT03092297 (registered 27 March 2017).

15.
Ann Med Surg (Lond) ; 86(7): 3827-3832, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38989235

RESUMO

Introduction: Hyaluronic acid (HA) fillers, popular for facial cosmetic enhancements, pose risks of vascular complications like skin necrosis due to arterial blockage, necessitating effective treatments such as hyperbaric oxygen therapy (HBOT). Methodology: This study presents a series of cases where measurements of transcutaneous oxygen pressure (TcPO2) informed the application of HBOT for skin necrosis induced by HA. Clinical presentation and outcomes: In cases 1 and 3, following the injection of HA, potential skin necrosis was observed. In addition to standard treatment, TcPO2 revealed values below 40 mmHg, indicating tissue hypoxia. Treatment with HBOT increased TcPO2 levels to above 200 mmHg, suggesting that HBOT could correct the hypoxia. Monitoring TcPO2 levels also aided in determining the optimal time to discontinue HBOT. In cases 2 and 4, patients received standard treatment, resulting in TcPO2 levels above 40 mmHg, indicating adequate tissue oxygenation, and no additional HBOT was administered. All four patients mentioned above showed good clinical recovery. Conclusion: This study investigates the application of TcPO2 measurement technology in aiding decisions on whether to utilize HBOT in the treatment of complications arising from HA fillers, as well as in optimizing HBOT protocols.

16.
J Colloid Interface Sci ; 674: 951-958, 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38959740

RESUMO

HYPOTHESIS: Our hypothesis is that dynamic interfacial tension values as measured by the partitioned-Edge-based Droplet GEneration (EDGE) tensiometry can be connected to those obtained with classical techniques, such as the automated drop tensiometer (ADT), expanding the range of timescales towards very short ones. EXPERIMENTS: Oil-water and air-water interfaces are studied, with whey protein isolate solutions (WPI, 2.5 - 10 wt%) as the continuous phase. The dispersed phase consists of pure hexadecane or air. The EDGE tensiometer and ADT are used to measure the interfacial (surface) tension at various timescales. A comparative assessment is carried out to identify differences between protein concentrations as well as between oil-water and air-water interfaces. FINDINGS: The EDGE tensiometer can measure at timescales down to a few milliseconds and up to around 10 s, while the ADT provides dynamic interfacial tension values after at least one second from droplet injection and typically is used to also cover hours. The interfacial tension values measured with both techniques exhibit overlap, implying that the techniques provide consistent and complementary information. Unlike the ADT, the EDGE tensiometer distinguishes differences in protein adsorption dynamics at protein concentrations as high as 10 wt% (which is the highest concentration tested) at both oil-water and air-water interfaces.

17.
Sci Rep ; 14(1): 13283, 2024 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-38858566

RESUMO

The tensile properties of coal under dynamic loading are important mechanical characteristics of coal and are highly important for controlling coal rock stability under impact loading conditions, selecting blasting engineering parameters, and studying the mechanism of rockburst disasters. To investigate the dynamic tensile failure process of coal subjected to impact loading, this study used high-speed photography and digital image correlation technology to capture the dynamic tensile failure of coal under impact loading. The dynamic tensile evolution was quantitatively analyzed from the beginning of coal sample being loaded to failure. The captured images of the coal were processed, and the fractal dimension was used to quantitatively describe the evolution of the coal surface cracks under impact loading. The following conclusions were drawn from the experimental results: (1) An empirical formula was established to describe the dynamic tensile strength characteristics of coal under different loading rates. (2) Under impact loading, the maximum strain of a Brazilian disc coal sample first appeared at the contact end between the sample and the incident rod. (3) Under impact loading, a Brazilian disc coal sample cracked from the center of the sample outward, and the crack subsequently extended toward both ends. The fractal dimension of the crack exhibited a power function relationship with time, and the variation range of the fractal dimension of the crack was 1.05-1.39.

18.
Knee ; 49: 108-115, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38880041

RESUMO

BACKGROUND: This study aimed to evaluate the effects of the differences in initial graft tension (IGT) on patellofemoral alignment in the axial plane after anatomical anterior cruciate ligament reconstruction (ACLR). METHODS: A total of 102 patients who underwent primary anatomical ACLR using a bone-patellar-tendon-bone autograft were enrolled. The grafts were fixed with maximum manual force at full knee extension (higher graft tension; H group) and with 5-20 N at 20° knee flexion which corresponded to 80 N at full knee extension (lower graft tension; L group) pulls in 39 and 63 patients, respectively. All patients underwent computed tomography of the bilateral knee joints with knee extension 1 week postoperatively. The patellofemoral alignment (sulcus angle, lateral trochlear inclination angle, lateral patellofemoral angle (LPFA), condylar-patellar angle (CPA) (lateral facet, patellar tilt), congruence angle, and bisect offset index) on the axial computed tomography images were evaluated, and the side-to-side differences (SSDs) between the injured knee and the contralateral knee were calculated. RESULTS: Congruence angle SSD was remarkably higher in the H group than in the L group (3.8 ± 4.7 vs. 0.4 ± 5.7, P < 0.01). Furthermore, the LPFA SSD and CPA (patellar tilt) SSD were significantly higher in the H group (-1.8 ± 3.1 vs. -0.4 ± 2.7, P = 0.04 and -1.6 ± 2.8 vs. -0.3 ± 2.7, P = 0.04, respectively). CONCLUSIONS: A higher IGT during anatomical ACLR induces a lateral shift and tilt of the patella against the femur immediately after surgery compared with the lower IGT.

19.
J Environ Manage ; 363: 121245, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38843729

RESUMO

This study investigates the impact of geopolitical risk on firm-level environmental, social, and governance (ESG) performance. Using a news-based indicator of geopolitical risk across 41 countries and a comprehensive dataset spanning from 2002 to 2021 with 65,354 firm-year observations, we uncover that geopolitical risk is negatively associated with ESG performance. Our findings remain robust even when considering alternative measures of geopolitical risk, ESG components, and sub-samples. Moreover, we address potential endogeneity concerns through two-stage least squares, propensity score matching and entropy balancing approaches. Interestingly, we find that the effect of geopolitical risk is positive for countries with lower geopolitical risk and high peace, indicating that relatively stable environments can incentivize firms to enhance their sustainability practices. We also examine the potential channel effects of cash holding, corporate investment, and cost of capital, and found significant effects. Overall, this paper underscores the significance of geopolitical risk as a macro-level shock that significantly influences ESG performance.


Assuntos
Política , Humanos , Conservação dos Recursos Naturais
20.
Heliyon ; 10(11): e32174, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38933960

RESUMO

Background: Acupuncture may be effective in treating tension-type headache (TTH). The durability of its effects after treatment completion remains inconclusive. Methods: We searched multiple databases and references from previous reviews for randomized controlled trials (RCTs) which investigated the effectiveness of acupuncture for TTH. We assessed the methodological quality of RCTs using the Cochrane Risk of Bias 2.0 (RoB 2) tool. Primary outcome was response rate, defined as the proportion of participants who reported at least a 50% reduction in monthly headache days from baseline after completion of treatment. Secondary outcomes included headache days, headache intensity, and analgesic use. Safety outcomes were also evaluated. Results: A total of seven RCTs involving 3,221 participants with frequent episodic and chronic TTH were included. Individuals receiving acupuncture reported a significantly higher response rate versus sham acupuncture (SA) immediately and at 1-6 months after completion of treatment (P<0.05). Compared with SA, post-treatment results of headache days and headache intensity appeared consistent on the whole, showing associations favoring acupuncture. However, no significant reduction in analgesic use was found post-treatment. Acupuncture showed no superiority over physical training or relaxation training in headache days and headache intensity. Moreover, no serious adverse events associated with acupuncture were reported. Conclusion: Limited evidence suggested that acupuncture might provide durable post-treatment effects in the management of frequent episodic and chronic TTH for up to 6 months compared with SA,with no severe treatment-related adverse events reported.

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