Intensely contracting fast skeletal muscle rapidly loses the ability to generate force, due in part to the accumulation of phosphate (P) inhibiting myosin's force-generating capacity, in a process that is strain dependent. Crucial aspects of the mechanism underlying this inhibition remain unclear. Therefore, we directly determined the effects of increasing [P] on rabbit psoas muscle myosin's ability to generate force against progressively higher resistive loads in a laser trap assay, with the requisite spatial and temporal resolution to discern the mechanism of inhibition. Myosin's force-generating capacity decreased with increasing [P], an effect that became more pronounced at higher resistive loads. The decrease in force resulted from myosin's accelerated detachment from actin, which also increased at higher resistive forces. These data are well fit by a cross-bridge model in which P rebinds to actomyosin in a postpowerstroke, ADP-bound state before accelerating myosin's detachment from actin. Thus, these findings provide important molecular insight into the mechanism underlying the P-induced loss of force during muscle fatigue from intense contractile activity.

Attempting to combine the mechanical and optical properties of ceramics and composite resins to mimic natural teeth has led to the emergence of resin nanoceramics and polymer interpenetrating ceramic network materials. Systematic reviews on the survival of these materials in endodontically treated teeth are lacking.

stingless bee propolis extract is known for its diverse bioactive compounds, making it a potential natural shield against UV radiation. This research assesses the photoprotective potential of crude ethanol extract from propolis collected from four structures (involucrum, pillar, pot, and entrance) of five bee hives (H1-H5), totalling 20 samples. Initially, the samples underwent testing for SPF value and UV absorption spectra. The crude ethanol extract (E) from the involucrum (H4) with the highest SPF value and broadest spectrum was selected for fractionation using hexane and water. Subsequently, the extract (E) and its hexane (H) and water (W) fractions were subjected to SPF analysis, UVA/UVB absorption assessment, determination of total phenolic and flavonoid content, free radical scavenging capacity, anti-collagenase effects, and cytotoxicity assessment. Additionally, LC-MS/MS analysis was performed to identify chemical constituents in the active fraction (W). The extract E demonstrated an SPF of 8.23 ± 0.09 and UV absorption. Notably, its fraction W exhibited the highest SPF (16.55 ± 0.24) at 100 μg/mL, surpassing the H fraction (SPF 5.7 ± 0.45). Phenolic content was highest in the H fraction (388.95 ± 4.54 mg/g GAE DW), followed by the W fraction (286.76 ± 6.48 mg/g GAE DW) and crude E (91.83 ± 4.12 mg/g GAE DW) from the involucrum. Regarding flavonoids, the fraction W led with 79.82 ± 6.21 mg/g QE DW, followed by the H fraction (45.56 ± 0.05 mg/g QE DW) and E (34.57 ± 1.11 mg/g QE DW). The extract E also exhibited modest DPPH scavenging (EC = 120 μg/mL), while the H fraction demonstrated stronger activity (EC = 4.37 μg/mL), and the W fraction displayed moderate effects (EC = 17.55 μg/mL). Notably, the W fraction showed remarkable anti-collagenase activity, outperforming the positive control, EG. HaCaT cell cytotoxicity revealed that the extract E was cytotoxic, whereas the H and W fractions showed no toxicity. LC-MS/MS analysis identified bioactive flavonoids (e.g., pratensein, quercetin) in the W fraction. These findings highlight the superior photoprotective properties of the water fraction from the involucrum of stingless bee propolis extract, suggesting its potential as a natural and effective ingredient for sunscreen and skincare formulations.

An artificial reef (AR) programme is being undertaken by the local fisheries authority in Terengganu, Malaysia, in an effort to mitigate the depletion of fish stocks in the coastal zone. This program is intended to protect inshore fishery habitats from trawls to increase fishery resources and improve the economic conditions of artisanal fishing communities. This article aims to present data on fishers' demographic characteristics and artificial reef fishing activity on Terengganu coastal water. Primary data were collected using stratified sampling that involved 430 respondents from four fishing communities in Terengganu, namely Setiu, Marang, Dungun and Kemaman. The dataset was obtained through a self-structured questionnaire. Data analysis and summary are presented using tables and figures. The findings provide valuable feedback on the socio-economic impact and economic value of artificial reefs to the fishermen and can be useful for policymakers to prevent the over-exploitation of fishery resources in Malaysian marine territories.

Multiscale models aiming to connect muscle's molecular and cellular function have been difficult to develop, in part due to a lack of self-consistent multiscale data. To address this gap, we measured the force response from single, skinned rabbit psoas muscle fibers to ramp shortenings and step stretches performed on the plateau region of the force-length relationship. We isolated myosin from the same muscles and, under similar conditions, performed single-molecule and ensemble measurements of myosin's ATP-dependent interaction with actin using laser trapping and in vitro motility assays. We fit the fiber data by developing a partial differential equation model that includes thick filament activation, whereby an increase in force on the thick filament pulls myosin out of an inhibited state. The model also includes a series elastic element and a parallel elastic element. This parallel elastic element models a titin-actin interaction proposed to account for the increase in isometric force after stretch (residual force enhancement). By optimizing the model fit to a subset of our fiber measurements, we specified seven unknown parameters. The model then successfully predicted the remainder of our fiber measurements and also our molecular measurements from the laser trap and in vitro motility. The success of the model suggests that our multiscale data are self-consistent and can serve as a testbed for other multiscale models. Moreover, the model captures the decrease in isometric force observed in our muscle fibers after active shortening (force depression), suggesting a molecular mechanism for force depression, whereby a parallel elastic element combines with thick filament activation to decrease the number of cycling cross-bridges.

Multiscale models aiming to connect muscle's molecular and cellular function have been difficult to develop, in part, due to a lack of self-consistent multiscale data. To address this gap, we measured the force response from single skinned rabbit psoas muscle fibers to ramp shortenings and step stretches performed on the plateau region of the force-length relationship. We isolated myosin from the same muscles and, under similar conditions, performed single molecule and ensemble measurements of myosin's ATP-dependent interaction with actin using laser trapping and in vitro motility assays. We fit the fiber data by developing a partial differential equation model that includes thick filament activation, whereby an increase in force on the thick filament pulls myosin out of an inhibited state. The model also includes a series elastic element and a parallel elastic element. This parallel elastic element models a titin-actin interaction proposed to account for the increase in isometric force following stretch (residual force enhancement). By optimizing the model fit to a subset of our fiber measurements, we specified seven unknown parameters. The model then successfully predicted the remainder of our fiber measurements and also our molecular measurements from the laser trap and in vitro motility. The success of the model suggests that our multiscale data are self-consistent and can serve as a testbed for other multiscale models. Moreover, the model captures the decrease in isometric force observed in our muscle fibers after active shortening (force depression), suggesting a molecular mechanism for force depression, whereby a parallel elastic element combines with thick filament activation to decrease the number of cycling cross-bridges.

To assess across seven hospitals from six different countries the extent to which the COVID-19 pandemic affected the volumes of orthopaedic hospital admissions and patient outcomes for non-COVID-19 patients admitted for orthopaedic care.

Myosin Va is the molecular motor that drives intracellular vesicular transport, powered by the transduction of chemical energy from ATP into mechanical work. The coupling of the powerstroke and phosphate (P) release is key to understanding the transduction process, and crucial details of this process remain unclear. Therefore, we determined the effect of elevated P on the force-generating capacity of a mini-ensemble of myosin Va S1 (WT) in a laser trap assay. By increasing the stiffness of the laser trap we determined the effect of increasing resistive loads on the rate of P-induced detachment from actin, and quantified this effect using the Bell approximation. We observed that WT myosin generated higher forces and larger displacements at the higher laser trap stiffnesses in the presence of 30 mM P, but binding event lifetimes decreased dramatically, which is most consistent with the powerstroke preceding the release of P from the active site. Repeating these experiments using a construct with a mutation in switch I of the active site (S217A) caused a seven-fold increase in the load-dependence of the P-induced detachment rate, suggesting that the S217A region of switch I may help mediate the load-dependence of P-rebinding.