Objective To detect the volume changes of cerebral gray and white matter in patients with maintaining hemodialysis using voxel-based morphometry(VBM) and to correlate these changes with cognitive function. Methods Forty-two patients with maintaining hemodialysis and 41 age and sex matched normal subjects were recruited in this study. MMSE was obtained to evaluate their neuropsychiatric conditions. Whole brain high-resolution T1WI was performed on 3.0 T MR scanner in both patients and normal controls. The data were analyzed by VBM based on SPM8, using analysis of functional neuroimages (AFNI) software package with the Monte Carlo simulation method(AlphaSim method) for multiple cluster level comparisons correction. Independent sample t test analysis was used to compare the volume of gray and white matter between the patients and normal controls. In addition, Stepwise multiple linear regression analysis was performed to explore the correlation between the voxel value of cerebral volume changes area and dialysis duration and clinical laboratory examination, and Spearman correlation analysis was used for the correlation between the left insula voxel values and neuropsychological test scores. Results Compared with normal controls, patients showed significantly decreased volume in the grey matter of the right putamen, the left putamen, the left insula (numbers of voxel in clusters were 455, 561, 162, t=-9.5681,-5.9516,-5.7185,P<0.001, AlphaSim-corrected). There was negative correlation between decreased grey matter volume of the right putamen[(0.53 ± 0.12)mm3]and the left putamen[(0.48 ± 0.12)mm3] and dialysis duration [19.0(1.5-114.0)months] (r=-0.330,-0.307,P<0.05). MMSE score of patients[29(21-30)score] was significantly lower than normal controls[30(28-30)score] (Z=-30.58,P<0.01). Decreased grey matter volume of the left insula [(0.39 ± 0.12) mm3] was positively correlated with MMSE(r=0.320, P<0.05). Conclusions The patients with maintaining hemodialysis show grey matter atrophy which is associated with neurocognitive dysfunction. Dialysis duration may be an important risk factor for decreased gray matter in patients with maintaining hemodialysis.

At present, the exact pathogenesis of dental fluorosis is not clear, and there is no exact standard of enamel acid etching in the adhesive restoration of dental fluorosis. Atomic force microscope represents a great progress in high-resolution imaging of biomaterials, and its advantage is that it can provide three-dimensional images and quantitative data of observed samples at the nanometer level. In recent years, the application of atomic force microscope in enamel study has made some progress. Whether the quantitative analysis of enamel ultrastructure can become a new way to study the pathogenesis of dental fluorosis and find the best repair method is worthy of further exploration. This paper reviews the application of atomic force microscope in the study of enamel with dental fluorosis.

Objective:To study the effects of recombinant human erythropoietin (rhEPO) on cerebral blood flow (CBF) in preterm infants using arterial spin labeling (ASL) magnetic resonance imaging (MRI).Methods:From September 2021 to June 2022, preterm infants (gestational age ≤32 weeks, birth weight ≤1 500 g) admitted to NICU of our hospital within 24 h after birth were randomly assigned into rhEPO group and control group for this prospective study. The rhEPO group was given rhEPO (500 IU/kg iv, once every other day for 2 weeks) within 72 h after birth plus symptomatic supportive treatment. The control group received same amount of normal saline injection. Both groups received brain MRI, diffusion-weighted imaging and ASL at adjusted gestational age of 35~37 weeks and CBF values of interested areas were measured.Results:A total of 85 infants were enrolled, including 40 in the rhEPO group and 45 in the control group. No significant differences existed in the incidences of periventricular-intraventricular hemorrhage, periventricular leukomalacia, focal white matter injury and extensive white matter injury between the two groups ( P>0.05). The CBF values [ml/(100 g·min)] of frontal cortex [left 15.1±3.9 vs. 17.9±3.1, right 15.9 (12.5, 17.8) vs. 18.1(16.1,20.2)], temporal cortex [left 15.8±4.3 vs. 18.6±3.8, right 16.3(13.2,19.4) vs. 18.1(15.7,19.7)], occipital cortex (left 15.8±6.1 vs. 18.8±3.3, right 16.8±5.5 vs. 19.3±4.8), basal ganglia (left 24.7±7.2 vs. 28.7±6.2, right 26.0±7.9 vs. 29.3±6.4) and thalamus (left 32.7±11.8 vs. 37.9±8.6, right 32.1±11.6 vs. 37.6±10.2) in the rhEPO group were significantly lower than the control group ( P<0.05). No significant differences existed of CBF value at the parietal cortex between the two groups ( P>0.05). Conclusions:Early application of rhEPO can reduce CBF in premature infants, which may be related to the neuro-protective effects of EPO.