Three-dimensional reconstruction of rat sperm using volume electron microscopy.

Three-dimensional (3D) reconstruction serves as a crucial instrument for the analysis of biological structures. In particular, a comprehensive and accurate 3D ultrastructural examination of rat sperm is vital for understanding and diagnosing male fertility issues and the underlying causes of infertility. In this study, we utilize the automated tape-collecting ultramicrotome scanning electron microscopy (ATUM-SEM) imaging technique, which is a highly effective method for 3D cellular ultrastructural analysis. Our findings reveal that during spermiogenesis, the volume of the nucleus significantly decreases, shrinking to just 10% of its original size. The acrosomal vesicles derived from the Golgi apparatus converge and elongate along the spermatid nucleus. These vesicles then attach to the nucleus via a cap-like structure, thereby defining the head side of the spermatozoa. In the initial stages of spermiogenesis, the mitochondria in spermatids are distributed beneath the cell membrane. As the process progresses, these mitochondria gradually migrate to the sperm tail, where they form the mitochondrial sheath. This sheath plays a crucial role in providing the energy required for the movement of the sperm. In addition, we reconstruct the mRNA-stroring structure-chromatoid body in sperm cells, which are cloud-like or net-like structures in the cytoplasm. The precise and comprehensive nature of 3D ultrastructural examination allows for a deeper understanding of the morphological process of spermiogenesis, thereby contributing to our knowledge of male fertility and the causes of infertility. Our research has significantly advanced the understanding of the 3D ultrastructure of sperm more comprehensively than ever before.

[Pathogens and risk factors for ventilator-associated pneumonia in children with congenial heart disease after surgery].

OBJECTIVE: To investigate the distribution and drug sensitivity of pathogens and risk factors for ventilator-associated pneumonia (VAP) in children with congenial heart disease (CAD) after surgery. METHODS: According to the occurrence of VAP, 312 children with CAD who received mechanical ventilation after surgery for 48 hours or longer between January 2012 and December 2014 were classified into VAP (n=53) and non-VAP groups (n=259). Sputum samples were collected and cultured for pathogens in children with VAP. The drug sensitivity of pathogens was analyzed. The risk factors for postoperative VAP were identified by multiple logistic regression analysis. RESULTS: The sputum cultures were positive in 51 out of 53 children with VAP, and a total of 63 positive strains were cultured, including 49 strains of Gram-negative bacteria (78%), 9 strains of Gram-positive bacteria (14%) and 5 strains of funqi (8%). The drug sensitivity test showed that Gram-negative bacteria were resistant to amoxicillin, piperacillin, cefotaxime and ceftazidime, with a resistance rate of above 74%, and demonstrated a sensitivity to amikacin, polymyxin and meropenem (resistance rate of 19%-32%). Single factor analysis showed albumin levels, preoperative use of antibiotics, duration of mechanical ventilation, times of tracheal intubation, duration of anesthesia agent use, duration of acrdiopulmonary bypass, duration of aortic occlusion and use of histamin2-receptor blockade were significantly different between the VAP and non-VAP groups (P<0.05). The multiple logistic regression showed albumin levels (<35 g/L), duration of mechanical ventilation (≥ 7 d), times of tracheal intubation (≥ 3), duration of acrdiopulmonary bypass (≥ 100 minutes) and duation of aortic occlusion (≥ 60 minutes) were independent risk factors for VAP in children with CAD after surgery. CONCLUSIONS: Gram-nagative bacteria are main pathogens for VAP in children with CAD after surgery. The antibiotics should be used based on the distribution of pathogens and drug sensitivity test results of pathogens. The effective measures for prevention of VAP should be taken according to the related risk factors for VAP to reduce the morbidity of VAP in children with CAD after surgery.

Powerful-IoU: More straightforward and faster bounding box regression loss with a nonmonotonic focusing mechanism.

Bounding box regression (BBR) is one of the core tasks in object detection, and the BBR loss function significantly impacts its performance. However, we have observed that existing IoU-based loss functions suffer from unreasonable penalty factors, leading to anchor boxes expanding during regression and significantly slowing down convergence. To address this issue, we intensively analyzed the reasons for anchor box enlargement. In response, we propose a Powerful-IoU (PIoU) loss function, which combines a target size-adaptive penalty factor and a gradient-adjusting function based on anchor box quality. The PIoU loss guides anchor boxes to regress along efficient paths, resulting in faster convergence than existing IoU-based losses. Additionally, we investigate the focusing mechanism and introduce a non-monotonic attention layer that was combined with PIoU to obtain a new loss function PIoU v2. PIoU v2 loss enhances the capability to focus on anchor boxes of medium quality. By incorporating PIoU v2 into popular object detectors such as YOLOv8 and DINO, we achieved an increase in average precision (AP) and improved performance compared to their original loss functions on the MS COCO and PASCAL VOC datasets, thus validating the effectiveness of our proposed improvement strategies.

Quantification of meropenem in serum and cerebrospinal fluid in children with bacterial meningitis with augmented renal clearance by UPLC-MS/MS.

Meropenem is an ultrabroad-spectrum antimicrobial agent that is often recommended for the treatment of bacterial meningitis (BM) in children. However, a subtherapeutic phenomenon occurred in BM children complicated with augmented renal clearance (ARC) at the recommended dose of meropenem. To support its pharmacokinetics, a sensitive, fast and robust ultra-liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to measure meropenem concentrations in serum and cerebrospinal fluid (CSF). The method involved protein precipitation, and samples were diluted with a large proportion of water to eliminate solvent effects. The separation of samples was performed on a Waters Acquity™ BEH C18 column (2.1 × 50 mm i.d., 1.7 µm) with a gradient profile. The mobile phases were formic acid-water (1:1000, v/v) and acetonitrile. The linear range was good, with a concentration range of 0.100-100 µg/mL for serum and 0.0400-20.0 µg/mL for CSF. The intra-day and inter-day precisions were less than 8.0%, and the intra-day and inter-day accuracies varied -6.6% from 6.5% for the both serum and CSF. The selectivity, carry-over, dilution integrity, matrix effect, recovery and stability were validated according to international guidelines. The developed UPLC-MS/MS method successfully determined the meropenem concentrations in the serum and CSF of children with BM complicated with ARC. The results indicated that under the recommended dosing regimen (40 mg/kg every 8 h), the time to reach the effective treatment target of 50%T > MIC was only approximately 3 h and lower CSF concentrations of meropenem were observed in children with BM with ARC.

Fear memory-associated synaptic and mitochondrial changes revealed by deep learning-based processing of electron microscopy data.

Serial section electron microscopy (ssEM) can provide comprehensive 3D ultrastructural information of the brain with exceptional computational cost. Targeted reconstruction of subcellular structures from ssEM datasets is less computationally demanding but still highly informative. We thus developed a region-CNN-based deep learning method to identify, segment, and reconstruct synapses and mitochondria to explore the structural plasticity of synapses and mitochondria in the auditory cortex of mice subjected to fear conditioning. Upon reconstructing over 135,000 mitochondria and 160,000 synapses, we find that fear conditioning significantly increases the number of mitochondria but decreases their size and promotes formation of multi-contact synapses, comprising a single axonal bouton and multiple postsynaptic sites from different dendrites. Modeling indicates that such multi-contact configuration increases the information storage capacity of new synapses by over 50%. With high accuracy and speed in reconstruction, our method yields structural and functional insight into cellular plasticity associated with fear learning.

[Study on the effects of cool and hot ethanol extracts from qinglongyi on the biochemical function of tumor membrane in H22 mice].

OBJECTIVE: To study the effects of cool and hot ethanol extracts from Qinglongyi on tumor membrane protein content, lipid fluidity, and membrane close capability in H22 mice. METHOD: The membrane protein content, by, lipid fluidity and membrane close capability were measured by means of SDS-PAGE, skinitzky assay and Zamudio method respectively. RESULT: The cool and hot ethanol extracts from Qinglongyi decreased the content of tumor membrane protein, the lipid fluidity and membrane close capability. CONCLUSION: The cool and hot ethanol extracts from Qinglongyi can change the biochemical substance and biochemical function to cause disaggregation and death of the tumor cell, which may be one of the mechanisms underlying the anti-tumor of Qinglongyi.

An efficient approach for production of polystyrene/poly(4-vinylpridine) particles with various morphologies based on dynamic control.

Polystyrene/poly(4-vinylpyridine) (PS/P4VP) particles with various morphologies such as popcorn-like (A), colloidal molecule NH(3) (B), colloidal molecule H(2)O (C) and mushroom-like (D) were generated by dynamically controlling and stabilizing the phase separation during the seeded swelling polymerization.