Malignant uveal melanoma and simulating lesions: MR imaging evaluation

Twenty-one patients with intraocular disease were studied by magnetic resonance (MR) imaging and computed tomography (CT). In 13 cases, malignant uveal melanoma was considered the likely diagnosis. Both imaging methods were accurate in determining the location and size of uveal melanomas. MR imaging was superior for the assessment of possible associated retinal detachment, for assessment of vitreous change, and for differentiating uveal melanoma from choroidal hemangioma and choroidal detachment. A case of retinal gliosis could not be differentiated from uveal melanoma by either technique. Uveal melanomas appeared as hyperintense lesions on T1-weighted images and as hypointense lesions on T2-weighted images. High signal intensity of the vitreous was observed in patients with vitritis and in those who were thought to have protein leaking into the vitreous as a result of impairment of the retinal-blood barrier.     

Bile duct stones: percutaneous transhepatic removal

Percutaneous transhepatic intervention for transduodenal removal of biliary stones was performed 38 times in 34 patients with obstructive jaundice, biliary colic, and cholangitis. The technique entailed the percutaneous transhepatic placement of a modified Dormia basket in the common duct with the flexible tip in the duodenum. The stones were passed into the duodenum and were crushed, or were crushed in the common duct and passed as fragments into the duodenum. In addition to the snare procedure, monooctanoin was used 18 times to dissolve remaining fragments of stone and sludge that could not be snared and passed into the duodenum. The average time for completion of the procedure was 10 days. There were no deaths from the procedure. The complication rate was 21%--probably no greater than would occur with surgery in a similar patient population. The procedure can be performed when endoscopic retrograde cholangiopancreatography and sphincterotomy with stone removal is technically impossible or refused, and in patients who have previously undergone choledochojejunostomy.     

Ongoing challenges in pediatric hospice care

Reports have begun to proliferate throughout the world which describe various models of pediatric hospice care. While encouraging, these reports identify universal obstacles that continue to compromise effective care. Challenges persist in areas of pain management, medical ethics, program administration, cost analysis, staff development and bereavement follow-up. Cooperative efforts are encouraged to address these issues.     

褪黑素对小鼠免疫性肝损伤的保护作用

目的观察褪黑素（MT）对小鼠免疫性肝损伤的影响。方法序贯注射短小棒状杆菌和脂多糖诱导小鼠免疫性肝损伤模型;在造模不同时间注射不同剂量MT;检测血浆转氨酶、肝脏雨二醛（MDA）和谷胱甘肽过氧化物酶（GSH-px）以及脾淋巴细胞增殖状况。结果造模期间用MT（0.1～10.0mg·kg-1）能显著降低血浆转氨酶和肝脏MDA水平（P＜0.05～0.01），使肝脏GSH-px活性部分恢复（P＜0.05），并能选择性抑制刀豆蛋白A诱导的脾淋巴细胞增殖。但造模后使用MT对免疫性肝损伤无明显影响。结论MT保护免疫性肝损伤作用与其抗氧化和免疫调节作用有关。     

The pathogenesis of diabetic retinopathy

Diabetic retinopathy remains a major cause of loss of vision. The Diabetes Control and Complications Trial (DCCT) has implicated hyperglycaemia as a probable major direct causative factor in the pathogenesis of diabetic retinopathy. There are several plausible mechanisms by which high glucose concentrations could lead to the functional and later structural changes characterising diabetic retinopathy. These include increased activity of the aldose reductase pathway, increase de novo synthesis of diacylglycerol from glucose, causing protein kinase C activation, increased non-enzymatic glycation and increased oxidative damage. The demonstration of the potential roles of these pathways and the subsequent effects of growth factors in enhancing angiogenesis provide potential new approaches to the prevention and treatment of diabetic retinopathy.     

High-resolution EEG mapping of cortical activation related to working memory: effects of task difficulty, type of processing, and practice

Changes in cortical activity during working memory tasks were examined with electroencephalograms (EEGs) sampled from 115 channels and spatially sharpened with magnetic resonance imaging (MRI)-based finite element deblurring. Eight subjects performed tasks requiring comparison of each stimulus to a preceding one on verbal or spatial attributes. A frontal midline theta rhythm increased in magnitude with increased memory load. Dipole models localized this signal to the region of the anterior cingulate cortex. A slow (low-frequency), parietocentral, alpha signal decreased with increased working memory load. These signals were insensitive to the type of stimulus attribute being processed. A faster (higher-frequency), occipitoparietal, alpha signal was relatively attenuated in the spatial version of the task, especially over the posterior right hemisphere. Theta and alpha signals increased, and overt performance improved, after practice on the tasks. Increases in theta with both increased task difficulty and with practice suggests that focusing attention required more effort after an extended test session. Decreased alpha in the difficult tasks indicates that this signal is inversely related to the amount of cortical resources allocated to task performance. Practice-related increases in alpha suggest that fewer cortical resources are required after skill development. These results serve: (i) to dissociate the effects of task difficulty and practice; (ii) to differentiate the involvement of posterior cortex in spatial versus verbal tasks; (iii) to localize frontal midline theta to the anteromedial cortex; and (iv) to demonstrate the feasibility of using anatomical MRIs to remove the blurring effect of the skull and scalp from the ongoing EEG. The results are discussed with respect to those obtained in a prior study of transient evoked potentials during working memory.