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Background This matters arising article addresses the recently published article in BMC Medicine by Cui et al., titled “Prophylactic effect of intraoperative sodium oxybate on postoperative delirium in older patients undergoing major orthopedic surgery: a randomized clinical trial.” Main body The work by Cui et al. demonstrated that intraoperative administration of sodium oxybate only significantly reduced postoperative delirium (POD) incidence in the participants undergoing morning surgery but not in those with afternoon surgery. Although this trial provided evidence that sodium oxybate may reduce POD, we raise several concerns regarding methodology and generalizability, such as incomplete control of perioperative risk factors, underestimated incidence of POD, subgroup analysis without multiple adjustments of confounding factors, and inadequate postoperative pain strategy. To verify the findings of this trial in further researches, we advocate the implementation of multi-center randomized clinical trials with large sample sizes, strict control of perioperative confounding factors, precise assessment of POD episodes, and the inclusion of subgroup analysis with multiple adjustments. Conclusion This matters arising does not seek to deny the results of Cui et al.’s trial. The main purpose of the authors is to emphasize that above methodological refinements are crucial for translating this valuable evidence into generally clinical practice and improving final outcomes of patients.

The letter to the editor was written in response to the recent article by Wang et al. “The influence of low-dose s-ketamine on postoperative delirium and cognitive function in older adults undergoing thoracic surgery”, which is published in Journal of Cardiothoracic Surgery. 2024; 19(1):324. This article concludes that intravenous low-dose S-ketamine during thoracic surgery in older patients significantly reduces the incidences of postoperative delirium and cognitive dysfunction, indicating a potential neuroprotective effect of intraoperative low-dose S-ketamine. In view to the retrospective nature of this study and their inconsistent findings with the results of a recent randomized controlled trial performed in patients undergoing non-cardiac thoracic surgery, we believe that several methodological issues and potential confounders in this study deserve further clarification and discussion before accepting their conclusions. Our main concerns include lacking the times and number of delirium monitoring per postoperative day, alone use of the Confusion Assessment Method form for delirium screening, not providing the factors related to the occurrence of postoperative delirium in the ICU stay, and application of a non-standard definition for postoperative cognitive impairment. We believe that clarification of these issues is useful for improving the transparency of their methodology and facilitating the interpretation of their results.

Recurrence-plot (RP) analysis is a graphical tool to visualize and analyze the recurrence of nonlinear dynamic systems. By combining the advantages of the RP and a convolutional neural network (CNN), a fault-classification scheme for planetary gear sets is proposed in this paper. In the proposed approach, a vibration is first picked up from the planetary-gear test rig and converted into an angular-domain quasistationary signal through computed order tracking to eliminate the frequency blur caused by speed fluctuations. Then, the signal in the angular domain is divided into several segments, and each segment is processed by the RP to constitute the training sample. Moreover, a two-dimensional CNN model was developed to adaptively extract faulty features. Experiments on a planetary-gear test rig with four conditions under three operating speeds were carried out. The results of measured vibration demonstrated the validity of CNN and recurrence plot analysis for the fault classification of planetary-gear sets.

Background Aptamer-based tumor targeted drug delivery system is a promising approach that may increase the efficacy of chemotherapy and reduce the related toxicity. HER2 protein is an attractive target for tumor-specific drug delivery because of its overexpression in multiple malignancies, including breast, gastric, ovarian, and lung cancers. Methods In this paper, we developed a new HER2 aptamer (HB5) by using systematic evolution of ligands by exponential enrichment technology (SELEX) and exploited its role as a targeting ligand for delivering doxorubicin (Dox) to breast cancer cells in vitro . Results The selected aptamer was an 86-nucleotide DNA molecule that bound to an epitope peptide of HER2 with a K d of 18.9 nM. The aptamer also bound to the extracellular domain (ECD) of HER2 protein with a K d of 316 nM , and had minimal cross reactivity to albumin or trypsin. In addition, the aptamer was found to preferentially bind to HER2-positive but not HER2-negative breast cancer cells. An aptamer-doxorubicin complex (Apt-Dox) was formulated by intercalating Dox into the DNA structure of HB5. The Apt-Dox complex could selectively deliver Dox to HER2-positive breast cancer cells while reducing the drug intake by HER2-negative cells in vitro . Moreover, Apt-Dox retained the cytotoxicity of Dox against HER2-positive breast cancer cells, but reduced the cytotoxicity to HER2-negative cells. Conclusions The results suggest that the selected HER2 aptamer may have application potentials in targeted therapy against HER2-positive breast cancer cells .

Keywords: Total hip arthroplasty, Postoperative analgesia, Regional blocks, Acute pain

We propose an efficient semi-analytical method capable of modeling the propagation of flexural waves on cracked plate structures with any forms of excitations, based on the same group of vibration characteristics and validated by a non-contact scanning Laser Doppler Vibrometer (LDV) system. The proposed modeling method is based on the superposition of the vibrational normal modes of the detected structure, which can be applied to analyze long-time and full-field transient wave propagations. By connecting the vibration-based transient model to a power flow analysis technique, we further analyze the transient waves on a cracked plate subjected to different excitation sources and show the influence of the damage event on the path of the propagating waves. The experimental results indicate that the proposed semi-analytical method can model the flexural waves, and through that, the crack information can be revealed.