Impact of brain segmentation methods on regional metabolism quantification in 18F-FDG PET/MR analysis.

BACKGROUND: Accurate analysis of quantitative PET data plays a crucial role in studying small, specific brain structures. The integration of PET and MRI through an integrated PET/MR system presents an opportunity to leverage the benefits of precisely aligned structural MRI and molecular PET images in both spatial and temporal dimensions. However, in many clinical workflows, PET studies are often performed without the aid of individually matched structural MRI scans, primarily for the sake of convenience in the data collection and brain segmentation possesses. Currently, two commonly employed segmentation strategies for brain PET analysis are distinguished: methods with or without MRI registration and methods employing either atlas-based or individual-based algorithms. Moreover, the development of artificial intelligence (AI)-assisted methods for predicting brain segmentation holds promise but requires further validation of their efficiency and accuracy for clinical applications. This study aims to compare and evaluate the correlations, consistencies, and differences among the above-mentioned brain segmentation strategies in quantification of brain metabolism in 18F-FDG PET/MR analysis. RESULTS: Strong correlations were observed among all methods (r = 0.932 to 0.999, P < 0.001). The variances attributable to subject and brain region were higher than those caused by segmentation methods (P < 0.001). However, intraclass correlation coefficient (ICC)s between methods with or without MRI registration ranged from 0.924 to 0.975, while ICCs between methods with atlas- or individual-based algorithms ranged from 0.741 to 0.879. Brain regions exhibiting significant standardized uptake values (SUV) differences due to segmentation methods were the basal ganglia nuclei (maximum to 11.50 ± 4.67%), and various cerebral cortexes in temporal and occipital regions (maximum to 18.03 ± 5.52%). The AI-based method demonstrated high correlation (r = 0.998 and 0.999, P < 0.001) and ICC (0.998 and 0.997) with FreeSurfer, substantially reducing the time from 8.13 h to 57 s on per subject. CONCLUSIONS: Different segmentation methods may have impact on the calculation of brain metabolism in basal ganglia nuclei and specific cerebral cortexes. The AI-based approach offers improved efficiency and is recommended for its enhanced performance.

[Effects of umbilical cord blood mononuclear cells transplantation via lateral ventricle on the neural apoptosis and the expression of Bax and Bcl-2 proteins in neonatal rats with hypoxic-ischemic brain damage].

OBJECTIVE: To explore the effects of umbilical cord blood mononuclear cells (UCBMC) transplantation on the neuronal apoptosis and the expression of Bcl-2 and Bax proteins in neonatal rats with hypoxic-ischemic brain damage (HIBD). METHODS: Seven-day-old Sprague-Dawley neonatal rats were randomly divided into normal control (N)+normal saline (NS), HIBD+NS, N+UCBMC, and HIBD+UCBMC groups. HIBD model was prepared using the classical Rice-Vannucci method. Twenty-four hours after HIBD, UCBMC were transplanted in the N+UCBMC and HIBD+UCBMC groups. Seven days after transplantation, NeuN/Cleaved-Caspase-3 double immunofluorescence staining and TUNEL methods were used to observe neural apoptosis in the cortex. The expression levels of Bax and Bcl-2 proteins were examined by Western blot analysis. RESULTS: There were more NeuN+ cleaved Caspase-3+DAPI+ and TUNEL+DAPI+ cells in the HIBD+NS group compared with the N+NS and N+UCBMC groups (P<0.01). There were less NeuN+ cleaved Caspase-3+DAPI+ and TUNEL+DAPI+ cells in the HIBD+UCBMC group compared with the HIBD+NS group (P<0.01). The concentration of Bax protein was higher and that of Bcl-2 proteins was lower in the HIBD+NS group compared with the N+NS and N+UCBMC groups (P<0.01). The concentration of Bax protein in HIBD+UCBMC group was lower than that in the HIBD+NS group (P<0.01). The concentration of Bcl-2 protein was higher compared with the HIBD+NS, N+NS and N+UCBMC groups (P<0.05). CONCLUSIONS: UCBMC transplantation via lateral ventricle can upregulate the expression of Bcl-2 protein and down-regulate the expression of Bax protein, thus alleviating brain neural apoptosis in neonatal rats with HIBD.

[Effects of umbilical cord mononuclear cells transplantation combined with hyperbaric oxygen therapy on hypoxic-ischemic brain damage in neonatal rats].

OBJECTIVE: To study the effects of umbilical cord monoculcear cells (UCBMC) transplantation combined with hyperbaric oxygen (HBO) therapy on the long-term behaviors and histology in neonatal rats after hypoxic-ischemic brain damage (HIBD). METHODS: Seven-day-old Sprague-Dawley rats were randomly assigned to four groups: normal control (CON), HIBD, UCBMC and UCBMC+HBO. HIBD was induced according to the Rice-Vannucci method. The rats in the UCBMC+HBO group were treated with HBO 3 hours after HIBD, followed by UCBMC transplantation 24 hours after HIBD. IL-1ß and TNF-α protein levels were examined by Western blot analysis in the 4 groups. T-maze test and radial arm maze test were used to detect the long-term learning memory capability. Nissl staining was used to examine the histological changes of the hippocampal CA1 region. RESULTS: Twenty-four hours after transplantation, IL-1ß and TNF-α protein levels in the UCBMC+HBO group were significantly reduced compared with the HIBD (P<0.01) and UCBMC groups (P<0.05). The study and memory capabilities were impaired, and the number of the pyramidal cells in the hippocampal CA1 region was reduced in the HIBD group. The study and memory capabilities were greatly improved and the number of pyramidal cells increased significantly in the UCBMC+HBO group compared with the UCBMC and HIBD groups (P<0.05). CONCLUSIONS: UCBMC transplantation combined with HBO therapy could reduce the expression of IL-1ß and TNF-α protein, improve long-term behaviors and alleviate brain damages in the hypoxic ischemic neonatal rats.

The impact of mgrA on progression of Staphylococcus aureus sepsis.

Sepsis induced by Staphylococcus aureus has worse outcome with the appearance of methicillin-resistant Staphylococcus aureus (MRSA) because of multi-resistance to a large group of antibiotics, which may lead to death from septic shock. Pathogenesis of S. aureus infections are involved in the production of a wide variety of virulence factors. MgrA, a noval global regulator, is a member of the MarR (multiple antibiotic resistance regulator)/SarA (staphylococcal accessory regulator A) family proteins, which plays a key role in regulating the expression of major virulence factors in S. aureus. In the present study, by using a murine model of sepsis, we investigated the role of mgrA in onset and progression of S. aureus induced sepsis. We found that mice inoculated with wild-type strain Newman had significantly higher mortality (p = 0.029), more weight lost, more bacterial load in blood, spleen and kidney, more intense inflammation response, and worse histopathology than mice inoculated with mgrA knockout strain. Our results has provided evidence that mgrA is a global regulator in S. aureus, and play an important role in S. aureus sepsis, could increase mortality and accelerate the onset and development of sepsis.