The central hypothesis for the development of glioblastoma multiforme (GBM) postulates that the tumor begins its development by transforming neural stem cells into cancer stem cells (CSC). Recently, it has become clear that another kind of stem cell, the mesenchymal stem cell (MSC), plays a role in the tumor stroma. Mesenchymal stem cells, along with their typical markers, can express neural markers and are capable of neural transdifferentiation. From this perspective, it is hypothesized that MSCs can give rise to CSC. In addition, MSCs suppress the immune cells through direct contact and secretory factors. Photodynamic therapy aims to selectively accumulate a photosensitizer in neoplastic cells, forming reactive oxygen species (ROS) upon irradiation, initiating death pathways. In our experiments, MSCs from 15 glioblastomas (GB-MSC) were isolated and cultured. The cells were treated with 5-ALA and irradiated. Flow cytometry and ELISA were used to detect the marker expression and soluble-factor secretion. The MSCs’ neural markers, Nestin, Sox2, and glial fibrillary acid protein (GFAP), were down-regulated, but the expression levels of the mesenchymal markers CD73, CD90, and CD105 were retained. The GB-MSCs also reduced their expression of PD-L1 and increased their secretion of PGE2. Our results give us grounds to speculate that the photodynamic impact on GB-MSCs reduces their capacity for neural transdifferentiation.

Introduction: The aim of this study was to present a novel technique for subthalamic nucleus (STN) deep brain stimulation (DBS) implantation under general anesthesia by using intraoperative motor-evoked potentials (MEPs) through direct lead stimulation and determining their correlation to the thresholds of postoperative stimulation-induced side effects. Methods: This study included 22 consecutive patients with advanced Parkinson’s disease who underwent surgery in our institution between January 2021 and September 2023. All patients underwent bilateral implantation in the STN (44 leads) under general anesthesia without microelectrode recordings (MERs) by using MEPs with electrostimulation directly through the DBS lead. No cortical stimulation was performed during this process. Intraoperative fluoroscopic guidance and immediate postoperative computed tomography were used to verify the electrode’s position. The lowest MEP thresholds were recorded and were correlated to the postoperative stimulation-induced side-effect threshold. The predictive values of the MEPs were analyzed. Five DBS leads were repositioned intraoperatively due to the MEP results. Results: A moderately strong positive correlation was found between the MEP threshold and the capsular side-effect threshold (RS = 0.425, 95% CI, 0.17–0.67, p = 0.004). The highest sensitivity and specificity for predicting a side-effect threshold of 5 mA were found to be at 2.4 mA MEP threshold (sensitivity 97%, specificity 87.5%, positive predictive value 97%, and negative predictive value 87.5%). We also found high sensitivity and specificity (100%) at 1.15 mA MEP threshold and 3 mA side-effect threshold. Out of the total 44 leads, 5 (11.3%) leads were repositioned intraoperatively due to MEP thresholds lower than 1 mA (4 leads) or higher than 5 mA (1 lead). The mean accuracy on postoperative CT was 1.05 mm, and there were no postoperative side-effects under 2.8 mA. Conclusion: Intraoperative MEPs with electrostimulation directly through the contacts of the DBS lead correlate with the stimulation-induced capsular side effects. The lead reposition based on intraoperative MEP may enlarge the therapeutic window of DBS stimulation.

Parkinson's disease (PD) significantly impedes, especially at its advanced stages, the health-related quality of life (QoL) of patients. The Parkinson's disease questionnaire (PDQ-39) is a widely-used measure assessing the impact of the disease on the patients' QoL. To date, the reliability of PDQ-39 has not been selectively evaluated for patients at a particular delineated stage of the PD progression. Against this backdrop, the study aimed firstly to evaluate comprehensively the internal consistency reliability of PDQ-39 and the constituent scales specifically for patients at the advanced stages of PD who were candidates for Deep Brain Stimulation (DBS) surgery, and secondly, to compare the Cronbach's alpha coefficients with those reported in other studies conducted with patients across all stages of the PD progression. The sample included 36 Bulgarian patients (29 men and 7 women) at advanced stages of PD (Hoehn and Yahr stage 4), PD duration, M = 11.06, SD = 3.50). The internal consistency reliability of the questionnaire and the constituent scales was assessed using three criteria: Cronbach's alpha coefficients, inter-item and item-total correlations. The internal consistency reliability indicators were satisfactory for the entire instrument and for most of the scales and similar to those reported in previous studies. None of the scales had low internal consistency reliability results across the three criteria. Except for the Communication scale, seven of the eight scales had Cronbach's alpha values that were satisfactory or marginally below the cut off score. All scales had acceptable inter-item correlations. Three of the scales (Emotional Well-Being, Cognition and Communication) contained more than one item with non-satisfactory item-total correlations. With minor exceptions, the removal of the items with low item-total correlations either did not improve or improved marginally or even decreased the Cronbach's alpha coefficients of the respective scale. The Communication scale was the only scale with a Cronbach's alpha coefficient that was both low and comparatively different to other studies and had as well low item-total correlations for all constituent items, thus showing non-satisfactory results on two of the three internal consistency reliability estimates. In contrast, the Mobility scale met all three internal consistency reliability criteria. PDQ-39 is a reliable tool for assessing the QoL of patients at advanced stages of PD across multiple health-related domains. The questionnaire can be recommended for inclusion in the best practice guidelines for evaluating DBS candidacy and the efficacy of DBS treatment for patients’ QoL.

As the main treatment modality of central neural system germinomas is radiotherapy and/or chemotherapy, the exact initial diagnosis of the disease is crucial. Depending on the different national protocols, histologic verification can be obligatory in some instances. This is a serious challenge, taking into account the usual location and nonspecific macroscopic appearance of these lesions. Here, we propose a safe and effective method of intraoperative tumor enhancement that can increase the confidence of the surgeon during the intervention.