Multimodal magnetic resonance imaging quantification of gray matter alterations in relapsing-remitting multiple sclerosis and neuromyelitis optica spectrum disorder.

Herein, we combined neurite orientation dispersion and density imaging (NODDI) and synthetic magnetic resonance imaging (SyMRI) to evaluate the spatial distribution and extent of gray matter (GM) microstructural alterations in patients with relapsing-remitting multiple sclerosis (RRMS) and neuromyelitis optica spectrum disorder (NMOSD). The NODDI (neurite density index [NDI], orientation dispersion index [ODI], and isotropic volume fraction [ISOVF]) and SyMRI (myelin volume fraction [MVF]) measures were compared between age- and sex-matched groups of 30 patients with RRMS (6 males and 24 females; mean age, 51.43 ± 8.02 years), 18 patients with anti-aquaporin-4 antibody-positive NMOSD (2 males and 16 females; mean age, 52.67 ± 16.07 years), and 19 healthy controls (6 males and 13 females; mean age, 51.47 ± 9.25 years) using GM-based spatial statistical analysis. Patients with RRMS showed reduced NDI and MVF and increased ODI and ISOVF, predominantly in the limbic and paralimbic regions, when compared with healthy controls, while only increases in ODI and ISOVF were observed when compared with NMOSD. Compared to NDI and MVF, the changes in ODI and ISOVF were observed more widely, including in the cerebellar cortex. These abnormalities were associated with disease progression and disability. In contrast, patients with NMOSD only showed reduced NDI mainly in the cerebellar, limbic, and paralimbic cortices when compared with healthy controls and patients with RRMS. Taken together, our study supports the notion that GM pathologies in RRMS are distinct from those of NMOSD. However, owing to the limitations of the study, the results should be cautiously interpreted.

Microstructural white matter abnormalities in multiple sclerosis and neuromyelitis optica spectrum disorders: Evaluation by advanced diffusion imaging.

INTRODUCTION: Despite differences in the pathogenesis and treatment of multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), it remains difficult to distinguish them. In this study, we aimed to discriminate between MS and NMOSD using diffusion tensor imaging (DTI), free water (FW) imaging, and neurite orientation dispersion and density imaging (NODDI). METHODS: Thirty patients with relapsing-remitting (RR) MS, 18 NMOSD patients with positive anti-aquaporin-4 immunoglobulin G seroreactivity, and 20 age- and sex- matched currently healthy subjects underwent MRI. The differences in the DTI (fractional anisotropy [FA], axial diffusivity [AD], mean diffusivity [MD], and radial diffusivity [RD]), FW and FW-corrected DTI, and NODDI indices between the three groups were evaluated using tract-based spatial statistics (TBSS) and region-of-interest (ROI) analyses. RESULTS: The ROI analysis of lesions indicated that the RRMS group had significantly higher AD, MD, RD, ISO and FW-corrected AD, and MD; and lower intracellular volume fraction (ICVF) than the NMOSD group. TBSS analysis showed increased water content in RRMS patients compared to NMOSD patients. Compared with healthy controls (HCs) using TBSS and ROI analysis, the changes in FW imaging indices were more limited than those of in DTI in RRMS patients. CONCLUSION: FW imaging and NODDI were useful for identifying the etiology of neurodegeneration- and neuroinflammation-related microstructural changes in RRMS and NMOSD patients.

Establishment of novel in vitro culture system with the ability to reproduce oral biofilm formation on dental materials.

Intensive research has been conducted with the aim of developing dental restorative/prosthetic materials with antibacterial and anti-biofilm effects that contribute to controlling bacterial infection in the oral cavity. In situ evaluations were performed to assess the clinical efficacy of these materials by exposing them to oral environments. However, it is difficult to recruit many participants to collect sufficient amount of data for scientific analysis. This study aimed to assemble an original flow-cell type bioreactor equipped with two flow routes and assess its usefulness by evaluating the ability to reproduce in situ oral biofilms formed on restorative materials. A drop of bacterial suspension collected from human saliva and 0.2% sucrose solution was introduced into the assembled bioreactor while maintaining the incubation conditions. The bioreactor was able to mimic the number of bacterial cells, live/dead bacterial volume, and volume fraction of live bacteria in the in situ oral biofilm formed on the surface of restorative materials. The usefulness of the established culture system was further validated by a clear demonstration of the anti-biofilm effects of a glass-ionomer cement incorporating zinc-releasing glasses when evaluated by this system.