Estimation of phase signal change in neuronal current MRI for evoke response of tactile detection with realistic somatosensory laminar network model

Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm³. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation.     

口服异维A酸治疗痤疮的研究

口服异维A酸是目前临床上最为有效的抗痤疮药物,可同时作用于痤疮发病的4个主要环节。异维A酸在皮脂腺细胞内独特的分子作用机制使其具有强大的抑制皮脂腺分泌活性,近来其对痤疮免疫和炎症反应的拮抗作用也越来越受到重视。口服异维A酸主要用于治疗结节囊肿型重度痤疮以及其他治疗效果不好的中、重度寻常痤疮,使用剂量应根据患者的体重、疗效、依从性及不良反应进行综合判定。小剂量[0.25~0.5 mg/(kg·d)]治疗可以显著降低药物的不良反应及增加患者依从性;累积剂量达60~120 mg/kg可以明显降低痤疮复发率。异维A酸不良反应大多以皮肤黏膜为主要表现,严重不良反应罕见,致畸是其最严重的不良反应。口服异维A酸能快速改善痤疮皮损,有效预防痤疮瘢痕形成,改善患者生活质量。     

靶向测序诊断黑棘皮病1家系

【摘要】 报道临床症状不典型的家族性黑棘皮病1家系。先证者女，4岁，自1周岁时，颈部、腹部出现黑色斑片，近年来逐渐扩大至唇周、躯干前部。腹部皮肤全反式共聚焦显微镜检查可见乳头环下延扭曲及沟壑结构，乳头环内可见中高折光颗粒结构。先证者父亲及祖母既往有类似病史，但随着年龄增长色素沉着自发性消退，仅有局部皮纹增粗。采集先证者及父母、祖母外周血，对先证者外周血DNA行Panel靶向测序，结果显示，先证者存在FGFR3基因14号外显子c.1949A>C（p.Lys650Thr）错义突变，Sanger测序验证证实先证者及其父亲和祖母均存在此突变。诊断：家族性黑棘皮病。     

Binding mode of conformations and structure-based pharmacophore development for farnesyltransferase inhibitors

Farnesyltransferase (FTase) is one of the prenyltransferase family enzymes that catalyse the transfer of 15-membered isoprenoid (farnesyl) moiety to the cysteine of CAAX motif-containing proteins including Rho and Ras family of G proteins. Inhibitors of FTase act as drugs for cancer, malaria, progeria and other diseases. In the present investigation, we have developed two structure-based pharmacophore models from protein–ligand complex (3E33 and 3E37) obtained from the protein data bank. Molecular dynamics (MD) simulations were performed on the complexes, and different conformers of the same complex were generated. These conformers were undergone protein–ligand interaction fingerprint (PLIF) analysis, and the fingerprint bits have been used for structure-based pharmacophore model development. The PLIF results showed that Lys164, Tyr166, TrpB106 and TyrB361 are the major interacting residues in both the complexes. The RMSD and RMSF analyses on the MD-simulated systems showed that the absence of FPP in the complex 3E37 has significant effect in the conformational changes of the ligands. During this conformational change, some interactions between the protein and the ligands are lost, but regained after some simulations (after 2 ns). The structure-based pharmacophore models showed that the hydrophobic and acceptor contours are predominantly present in the models. The pharmacophore models were validated using reference compounds, which significantly identified as HITs with smaller RMSD values. The developed structure-based pharmacophore models are significant, and the methodology used in this study is novel from the existing methods (the original X-ray crystallographic coordination of the ligands is used for the model building). In our study, along with the original coordination of the ligand, different conformers of the same complex (protein–ligand) are used. It concluded that the developed methodology is significant for the virtual screening of novel molecules on different targets.