Automatic segmentation of the female pelvic floor muscles on MRI for pelvic floor function assessment.

Background: Pelvic organ prolapse (POP) is a pelvic floor dysfunction disease which affects females. The volume of pelvic floor muscle, especially the levator ani muscle (LAM), is an important indicator of pelvic floor function. However, muscle volume measurements depend on manual segmentation, which is clinically time-consuming. In this work, we present an efficient automatic segmentation model of pelvic floor muscles with magnetic resonance imaging (MRI) based on DenseUnet, to achieve muscle volume calculation and provide a reference for the assessment of pelvic floor function. Methods: A total of 49 female pelvic floor magnetic resonance (MR) series were retrospectively enrolled from the First Affiliated Hospital of Army Military Medical University between 2013 and 2021, including 21 normal participants and 28 patients with stage 1-4 POP. The LAM, internal obturator muscle (IOM), and external anal sphincter (EAS) were manually segmented. An improved DenseUnet was proposed for automatic segmentation of these 3 muscles. The Dice similarity coefficient (DSC), Hausdorff distance (HD), and average symmetrical surface distance (ASSD) were used to evaluate segmentation results. The segmentation performance of the improved DenseUnet was compared with those of standard DenseUnet, ResUnet, Unet++, and Unet. Results: The improved DenseUnet showed a good performance. The average DSC and standard deviation of the LAM, IOM, and EAS was 0.758±0.151, 0.716±0.173, and 0.810±0.147, respectively. The average HD was 22.41, 19.00, and 36.01 mm, respectively; and the average ASSD was 3.66, 3.80, and 5.23 mm, respectively. The average DSC and standard deviation of the normal group and POP group was 0.779±0.166 and 0.757±0.154, respectively. There was no significant difference between the muscle volume of the improved DenseUnet and manual segmentation (all P values >0.05). The average total segmentation time for 1 case was 10.18 s on our setup, which is much lower than the manual segmentation time of 45 minutes. Conclusions: The improved DenseUnet segments the pelvic floor muscles in MRI quickly and efficiently, with good precision and faster speed than those of manual segmentation. This can assist doctors in quickly segmenting pelvic floor muscles, calculating muscle volume, and further evaluating pelvic floor function.

Glutathione peroxidase 4 maintains a stemness phenotype, oxidative homeostasis and regulates biological processes in Panc­1 cancer stem­like cells.

Reactive oxygen species (ROS) have been widely accepted as critical molecules playing regulatory roles in various biological processes, including proliferation, differentiation and apoptotic/ferroptotic/necrotic cell death. Emerging evidence suggests that ROS may be involved in the induction of epithelial­to­mesenchymal transition (EMT), which has been reported to promote cancer stem­like cell (CSC) generation. Recent data indicate that altered accumulation of ROS is associated with CSC generation, EMT and hypoxia exposure, but the underlying mechanisms are poorly understood. In the present study, we derived CSCs from Panc­1 human pancreatic cancer cells and characterized them using serial replating assays and western blot analysis. Functional identification of viable cells was performed using the CCK­8 assay and colony formation assays. The expression of various antioxidant enzymes, including superoxide dismutase (SOD) and glutathione peroxidase (GPX), was measured by western blot analysis in Panc­1 CSCs. The role of GPX4 in regulating biological processes of Panc­1 CSCs was assessed by proliferation, sphere formation and invasion assays with or without oxidative stress. Manipulation of GPX4 expression by siRNA knockdown or an overexpression vector was performed to assess functions including proliferation, colony formation and invasion. EMT hallmark genes were detected after GPX4 alteration by RT­qPCR and western blot analysis. Panc­1 CSCs displayed more resistance to hypoxia exposure. Compared with the parental Panc­1 cells, Panc­1 CSCs expressed an obviously higher endogenous GPX4 level, indicating their role in maintaining homeostasis. During GPX4 knockdown, ROS accumulation was promoted following oxidative stress exposure to either H2O2 or erastin. Additionally, overexpression of GPX4 eliminated ROS induction by oxidative stress exposure and thus, exerted protective effects on physiological processes in the Panc­1 CSCs. Knockdown of GPX4 arrested cell cycle progression at the G1/G0 phase; inhibited cell proliferation, colony formation, invasion and the stemness phenotype in the Panc­1 CSCs; and decreased the EMT phenotype. Collectively, GPX4 plays a critical role in maintaining oxidative homeostasis and regulates several biological processes, including stemness and EMT, in Panc­1 CSCs.

Design of micromachined self-focusing piezoelectric composite ultrasound transducer.

Based on the Fresnel half-wave band interference, a micromachined self-focusing piezoelectric composite ultrasound transducer was proposed in this paper. The theoretical analysis was deduced based on the concept of constructive interference of acoustic waves and electromechanical response of piezoelectric composites. The calculated and simulation results showed that it combined the advantages of composite transducer and plate self-focusing transducer, and can achieve high electromechanical coupling coefficient, low acoustic impedance, high intensity, short focal length and micro size. Because it was based on the micro-electromechanical systems, the fabrication process was accurate and controllable, which made it have good potential for interventional ultrasound imaging, cellular microstructure imaging, skin cancer detection and industrial nondestructive testing applications.