Fast decomposition of water and lipid using a GRASE technique with the IDEAL algorithm.

Three-point Dixon techniques achieve good lipid-water separation by estimating the phase due to field inhomogeneities. Recently it was demonstrated that the combination of an iterative algorithm (iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)) with a fast spin-echo (FSE) three-point Dixon method yielded robust lipid-water decomposition. As an alternative to FSE, the gradient- and spin-echo (GRASE) technique has been developed for efficient data collection. In this work we present a method for lipid-water separation by combining IDEAL with the GRASE technique. An approach to correct for errors in the lipid-water decomposition caused by phase distortions due to the switching of the readout gradient polarities inherent to GRASE is presented. The IDEAL-GRASE technique is demonstrated in phantoms and in vivo for various applications, including pelvic, musculoskeletal, and (breath-hold) cardiac imaging.     

Water- and fat-suppressed proton projection MRI (WASPI) of rat femur bone.

Investigators often study rats by microCT to investigate the pathogenesis and treatment of skeletal disorders in humans. However, microCT measurements provide information only on bone mineral content and not the solid matrix. CT scans are often carried out on cancellous bone, which contains a significant volume of marrow cells, stroma, water, and fat, and thus the apparent bone mineral density (BMD) does not reflect the mineral density within the matrix, where the mineral crystals are localized. Water- and fat-suppressed solid-state proton projection imaging (WASPI) was utilized in this study to image the solid matrix content (collagen, tightly bound water, and other immobile molecules) of rat femur specimens, and meet the challenges of small sample size and demanding submillimeter resolution. A method is introduced to recover the central region of k-space, which is always lost in the receiver dead time when free induction decays (FIDs) are acquired. With this approach, points near the k-space origin are sampled under a small number of radial projections at reduced gradient strength. The typical scan time for the current WASPI experiments was 2 hr. Proton solid-matrix images of rat femurs with 0.4-mm resolution and 12-mm field of view (FOV) were obtained. This method provides a noninvasive means of studying bone matrix in small animals.     

Adiabatic refocusing pulses for volume selection in magnetic resonance spectroscopic imaging.

Because of their excellent slice profiles and high immunity to RF inhomogeneity, adiabatic full passage (AFP) pulses are ideal for use in spatial localization. The nonlinear, position-dependent phase of a single AFP pulse generated during refocusing of transverse magnetization traditionally is eliminated by using identical pairs of AFP pulses, at the expense of increased RF power deposition and increased echo time (TE). Here it is shown that one can achieve significant phase refocusing by executing single AFP pulses along non-equivalent spatial axes. When used for volume selection in MR spectroscopic imaging (MRSI) the remaining nonlinear phase becomes inconsequential when the phase across a spectroscopic volume is small. Selection of rectangular and octagonal volumes is demonstrated with half the number of AFP pulses used in the traditional approach. It is shown that octagonal volume selection in the human brain provides excellent suppression of extracranial lipids, and thus allows multislice (1)H MRSI at 4 Tesla to be performed within the guidelines for RF power deposition.     

Valganciclovir Dosing According to Body Surface Area and Renal Function in Pediatric Solid Organ Transplant Recipients

Oral valganciclovir is effective prophylaxis for cytomegalovirus (CMV) disease in adults receiving solid organ transplantation (SOT). However, data in pediatrics are limited. This study evaluated the pharmacokinetics and safety of valganciclovir oral solution or tablets in 63 pediatric SOT recipients at risk of CMV disease, including 17 recipients ≤2 years old. Patients received up to 100 days' valganciclovir prophylaxis; dosage was calculated using the algorithm: dose (mg) = 7 × body surface area × creatinine clearance (Schwartz method; CrCLS). Ganciclovir pharmacokinetics were described using a population pharmacokinetic approach. Safety endpoints were measured up to week 26. Mean estimated ganciclovir exposures showed no clear relationship to either body size or renal function, indicating that the dosing algorithm adequately accounted for both these variables. Mean ganciclovir exposures, across age groups and organ recipient groups were: kidney 51.8 ± 11.9 μg * h/mL; liver 61.7 ± 29.5 μg * h/mL; heart 58.0 ± 21.8 μg * h/mL. Treatment was well tolerated, with a safety profile similar to that in adults. Seven serious treatment-related adverse events (AEs) occurred in five patients. Two patients had CMV viremia during treatment but none experienced CMV disease. In conclusion, a valganciclovir-dosing algorithm that adjusted for body surface area and renal function provides ganciclovir exposures similar to those established as safe and effective in adults     

板蓝根磷脂对内毒素血症小鼠巨噬细胞膜脂流动性的影响

目的　以小鼠内毒素血症为模型 ,观察板蓝根磷脂对内毒素血症小鼠巨噬细胞膜脂流动性的保护作用。方法　小鼠分为板蓝根氯仿提取物预处理组、磷脂脂质体预处理组、板蓝根磷脂脂质体预处理组和内毒素血症对照组。各组按照上述次序分别给予腹腔注射 5ml/kg相应药物 ,预处理 18h后腹腔注射内毒素 6mg/kg。 6h后处死小鼠 ,观察细胞膜脂流动性的变化。结果　板蓝根氯仿提取物对内毒素血症小鼠巨噬细胞膜脂流动性的保护作用没有达到具有统计学意义的程度 (P >0 .0 5 ) ,磷脂脂质体对膜脂流动性具有保护作用 (P <0 .0 5 ) ,但两者之间并没有统计学上的差别 (P >0 .0 5 ) ;板蓝根磷脂对内毒素血症小鼠细胞膜脂流动性具有明显的保护作用 (P <0 .0 1) ,优于单独使用板蓝根氯仿提取物 (P <0 .0 5 )或磷脂脂质体 (P =0 .0 5 )。结论　板蓝根磷脂脂质体对内毒素血症小鼠巨噬细胞膜脂流动性的保护作用优于单独使用板蓝根氯仿提取物或磷脂脂质体     

Combining microwave‐enhanced deuteriation reactions with parallel synthesis procedures

The development of combined microwave‐enhanced/parallel synthesis procedures and their application to the deuteriation of organic compounds via examples of solid‐state hydrogenation is reported. Other labelling procedures, such as solution state catalytic dehalogenations, hydrogenations as well as hydrogen isotope exchange reactions also benefit from the combined technology. Copyright © 2003 John Wiley & Sons, Ltd.     

通塞益脑液治疗急性脑梗塞的机理探讨

本文以结扎左侧颈总动脉造成实验性急性脑梗塞的沙土鼠模型,探讨通塞益脑液治疗急性脑梗塞的机理。发现结扎术前胃饲通塞益脑液者,可降低急性脑梗塞后脑组织中过氧化脂质的含量;结扎术后给药者,可降低脑组织中钙的含量。初步认为通塞益脑液对急性脑梗塞的脑组织有保护作用。     

Permeability of pure lipid bilayers to melatonin

Abstract: Melatonin, the chief hormone of the pineal gland, has been reported to interact with a variety of different cells. This ubiquitously acting hormone has been found to interact with protein receptors both at the cell membrane and in the nucleus. Moreover, melatonin was recently shown to be a very potent hydroxyl radical scavenger. The present work focuses on the interaction of melatonin with pure lipid bilayers. It is shown that melatonin can cross multilamellar lipid vesicles, which are used here as model systems for the lipid phase of biological membranes. Thus, the data prove that melatonin can easily pass through the cell membrane and bath every part of the cell, as previously suggested in the literature. Melatonin lipid association constant was calculated based on the change of the hormone fluorescence intensity due to its penetration into the hydrophobic lipid phase. Though melatonin was recently shown to be highly soluble in aqueous media, its lipid association constant is rather high, indicating that the biological action of the hormone is likely to be at the membrane level, either via its interaction with membrane receptors, and/or as a lipoperoxidation radical scavenger.     

豆渣纤维的降脂作用及对血液流变学影响的研究

以ＳＤ大鼠为对象，研究了豆渣纤维对高胆固醇膳动物脂质代谢和血流变性的影响，并与果胶和纯纤维素进行比较，结果表明：８周实验后，豆渣与果胶组动物的血清总胆固醇（ＴＣ）和低密度脂蛋白胆固醇（ＬＤＬ－Ｃ）显著降低，但豆渣组的血脂水平比果胶组更低（Ｐ＜０．０５）。而纯纤维素组未显出降脂作用。各组大鼠的甘油三醋（ＴＧ）和高密度脂蛋白胆固醇（ＨＤＬ－Ｃ）也无明显变化。实验同时表明，６％的豆渣纤维与果胶均可使高脂大鼠的血粘度及血小板聚集率降低（Ｐ＜０．０５），且前者优于后者。相关分析显示，血脂与血流变学指标间存在显著相关性（Ｐ＜０．０５），其中ＴＣ与ＬＤＬ－Ｃ是影响血流变性的重要因素。６％的以上各种纤维摄入量均不影响大鼠的摄食量与生长。