Micro- and macro-changes in early-stage type 2 diabetes mellitus without cognitive impairment: a diffusion tensor imaging (DTI) and surface-based morphometry (SBM) study.

Introduction: Brain structure and function changes are considered major brain damages in type 2 diabetes mellitus (T2DM), which likely has a close relationship with cognitive impairment. Many previous studies have shown by using brain structural and functional magnetic resonance imaging (MRI) methods that brain white and gray matter are damaged in T2DM, leading to cognitive impairment. Researches neglected patients of T2DM without cognitive dysfunction might also have brain changes. Methods: In this study, subjects with early stage T2DM with no cognitive dysfunction were enrolled to detect brain damages using the tract-based spatial statistics analysis (TBSS) method to demonstrate white matter (WM) micro changes and surface-based morphometry (SBM) method to assess cerebral cortex macro changes. Results: The whole-brain TBSS analysis revealed that there were no statistically significant changes in fractional anisotropy (FA) and mean diffusivity (MD), but the FA declined in some area of cerebral WM (p < 0.1). The SBM results showed no changes in cortical thickness (CT), cortical volume (CV), surface area (SA), and cortical sulcal curve (CSC) between these two groups, but pial local gyration index (LGI) was decreased in the precuneus (-log10, p = -3.327). Discussion: In conclusion, early stage T2DM patients without cognitive impairment had brain micro and macro structural damages, suggesting the potential use of MRI as an imaging marker to detect brain changes in early stage T2DM, which could not be observed and assessed clinically.

Imaging of nuclear Overhauser enhancement at 7 and 3 T.

Nuclear Overhauser enhancement (NOE) is a type of magnetization transfer using cross-relaxation. It originates from mobile macromolecules, which may have relevance to the evaluation of tumor features. We studied the value of NOE imaging at 7 and 3 T and suggest a utility for diagnosing human brain tumors. Two types of protein solution at different concentrations and pH values, and six normal Sprague Dawley (SD) rats, were used to detect NOE signal with a 7 T scanner. Then, six healthy volunteers and 11 patients with brain tumors (six gliomas and five meningiomas) were included at 3 T. Z-spectra were measured and NOE weighted (NOE*) images were acquired with a three-offset measurement. Wide spectral separation was shown at both 7 T and 3 T delineating the NOE peak in the Z-spectrum. The concentration dependence and pH independence of NOE were confirmed in phantom experiments, and NOE values were greater in white matter than in gray matter in vivo. At 3 T, data indicated that NOE* maps were slightly hypointense in gliomas and were not obviously different from meningiomas. Thus, NOE imaging may help distinguish benign from malignant tumors, and as such may contribute to diagnosing brain tumors.

Nuclear Overhauser Enhancement-Mediated Magnetization Transfer Imaging in Glioma with Different Progression at 7 T.

Glioma is a malignant neoplasm affecting the central nervous system. The conventional approaches to diagnosis, such as T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), and contrast-enhanced T1WI, give an oversimplified representation of anatomic structures. Nuclear Overhauser enhancement (NOE) imaging is a special form of magnetization transfer (MT) that provides a new way to detect small solute pools through indirect measurement of attenuated water signals, and makes it possible to probe semisolid macromolecular protons. In this study, we investigated the correlation between the effect of NOE-mediated imaging and progression of glioma in a rat tumor model. We found that the NOE signal decreased in tumor region, and signal of tumor center and peritumoral normal tissue markedly decreased with growth of the glioma. At the same time, NOE signal in contralateral normal tissue dropped relatively late (at about day 16-20 after implanting the glioma cells). NOE imaging is a new contrast method that may provide helpful insights into the pathophysiology of glioma with regard to mobile proteins, lipids, and other metabolites. Further, NOE images differentiate normal brain tissue from glioma tissue at a molecular level. Our study indicates that NOE-mediated imaging is a new and promising approach for estimation of tumor progression.

The Neurochemical and Microstructural Changes in the Brain of Systemic Lupus Erythematosus Patients: A Multimodal MRI Study.

The diagnosis and pathology of neuropsychiatric systemic lupus erythematosus (NPSLE) remains challenging. Herein, we used multimodal imaging to assess anatomical and functional changes in brains of SLE patients instead of a single MRI approach generally used in previous studies. Twenty-two NPSLE patients, 21 non-NPSLE patients and 20 healthy controls (HCs) underwent 3.0 T MRI with multivoxel magnetic resonance spectroscopy, T1-weighted volumetric images for voxel based morphometry (VBM) and diffusional kurtosis imaging (DKI) scans. While there were findings in other basal ganglia regions, the most consistent findings were observed in the posterior cingulate gyrus (PCG). The reduction of multiple metabolite concentration was observed in the PCG in the two patient groups, and the NPSLE patients were more prominent. The two patient groups displayed lower diffusional kurtosis (MK) values in the bilateral PCG compared with HCs (p < 0.01) as assessed by DKI. Grey matter reduction in the PCG was observed in the NPSLE group using VBM. Positive correlations among cognitive function scores and imaging metrics in bilateral PCG were detected. Multimodal imaging is useful for evaluating SLE subjects and potentially determining disease pathology. Impairments of cognitive function in SLE patients may be interpreted by metabolic and microstructural changes in the PCG.

[Negative regulation on PCA production is not correlated with positive regulation on BHL and HHL synthesis by gacA in Pseudomonas sp. M18].

At least 5 kinds of N-acyl-homoserine lactones(AHLs) were identified in Pseudomonas sp. M18. They were: N-butyryl-L-homoserine lactone(C4-HSL, BHL), N-hexanoyl-L-homoserine lactone(C6-HSL, HHL), N-(3-oxohexanoyl)-L-homoserine lactone(3-Oxo-C6-HSL, OHHL), N-(3-oxooctanoyl)-L-homoserine lactone (3-Oxo-C8-HSL, OOHL) and N-(3-oxodecanoyl)-L-homoserine lactone(3-Oxo-C10-HSL, ODHL). Compared with the wide-type strain M18, the variety of the AHLs in the gacA mutant strain M18G reduced to 4 species with the decreased quantity. But the phenazine-1-carboxylic acid (PCA) production was increased by about 2-fold. The product of rhll plays an important role in synthesizing BHL and HHL. The rhll'-'lacZ translational fusion expression plasmid pMEIZ was constructed in vector pME6015 and then was introduced into the wild-type strain M18 and the gacA mutant strain M18G. The galactosidase activity in chromosomal gacA disruption mutant was only 60% of that in the wild-type strain M18. This result suggested that GacA could regulate the rhll expression positively. There was no influence on PCA production by adding exogenous BHL and HHL and both together to the culture of strains M18 and M18G. This result suggested that there was no relation between GacA's negative regulation on PCA production and positive regulation on BHL and HHL synthesis.