Comparison of the retrieval of item versus spatial position information

It has been argued that temporal and spatial position information are represented similarly, but prior research comparing their time course of retrieval with item information has not supported this conclusion. The time course of retrieval was compared for spatial position and item information in 3 response signal experiments, and differences were found in the time course of retrieval that paralleled those found previously for temporal position and item information (B.M. McElree & B.A. Dosher, 1993). The finding was unaffected by restrictions on the degree of relational support, postretrieval decision difficulty, and the elimination of a strategy favoring item recognition. The authors conclude by discussing whether the data indicate that a recall process was contributing to recognition performance.     

Automatic internal cardioverter-defibrillator patch erosion into the upper airway presenting as a cavitary lesion

Erosion of an automatic internal cardioverter-defibrillator (AICD) patch into the lingular bronchus occurred 4 years after implantation; the erosion presented as a cavitary mass associated with hemoptysis and weight loss. On bronchoscopy to evaluate for suspected carcinoma, a cavity was entered through a bronchial defect and the AICD patch clearly identified. The complication was successfully treated with patch removal and fistula closure.     

Administration of dehydroepiandrosterone sulfate retards onset but not progression of autoimmune disease in NZB/W mice

A series of silica gels and mesoporous molecular sieves differing in both the range of particle size and mean pore size were derivatized with the p-[R,S-alpha-[1-(9H-fluoren-9-yl)-methoxyformamido]-2,4-di methoxybenzyl]- phenoxyacetic acid linker and their loading capacities were measured. Loading capacities ranging between 0.4-0.6 mmol Fmoc/g were achieved. Several of these silica based materials were derivatized with the hydroxymethyl benzoic acid linker and used as supports for the solid phase Claisen rearrangement of a support bound phenyl allyl ether. Both the silica gel and mesoporous supports were heated at 225 degrees C for 3 h to effect the Claisen rearrangement. The results showed that, compared to the same reaction run homogeneously, the silica gel support achieved similar total product yields and ratios for two Claisen products. The mesoporous supports were found to selectively produce one of the Claisen products over the other. Analysis shows that the molecules bound to the mesoporous support are physically further separated from each other as compared to those bound to the silica gel support. A mechanism is presented which accounts for the selectivity of the mesoporous support in forming one Claisen product over the other. The Claisen product was further derivatized to the resulting phenyl ethyl either through a solid phase Mitsunobu reaction on the mesoporous support.     

Gene therapy: a primer for radiologists

Gene therapy is one of the most rapidly evolving areas in medicine. Radiologists should have an understanding of basic techniques used to identify and clone a gene and insert it into a vector capable of directing expression in mammalian tissues. DNA delivery systems include retroviral vectors (RNA viruses), adenoviral vectors (DNA viruses), and cationic liposomes, along with strategies that involve ultrasound-directed gene transfer, computed tomography-guided gene transfer, and transcatheter gene delivery, in particular via the hepatic artery. Genes being evaluated in preclinical and clinical trials include oncogenes, antioncogenes (tumor suppressor genes), suicide genes, conventional antimetabolites, antiangiogenesis factors, secreted immunostimulatory cytokines such as interleukins and interferons, and immunomodulatory cell surface proteins, including foreign HLA proteins and costimulatory molecules. A foundation in molecular biology is needed for the practicing radiologist interested in but unfamiliar with current gene therapy terminology and experimental strategies. Such a foundation will encourage the dissemination of basic biologic, diagnostic imaging, and interventional oncoradiologic developments and should facilitate integration of the radiologist into the gene therapy team.     

Cooperative studies in health services research in the Department of Veterans Affairs

We present data on the costs and impact of chronic renal failure, the primary renal diseases leading to end-stage renal disease in children, and review the adaptive responses and the pathophysiology and complications of uremia in experimental animals and in man. A treatment strategy is summarized.     

Direct visualization of uridylate deletion in vitro suggests a mechanism for kinetoplastid RNA editing

Deletion of uridylates from the 3'-most editing site of synthetic ATPase 6 pre-mRNA can be visualized directly by coincubation of a radiolabeled substrate RNA and a synthetic gRNA in 20S fractions of T.brucie mitochondrial lysates. Substrate RNA cleavage is gRNA directed and occurs 3' to the uridylates to be deleted. U residues appear to be sequentially removed from the 3' end of the 5' cleavage product prior to religation of the two pre-mRNA halves. gRNA/mRNA chimeric molecules are also produced. Time course experiments indicate that chimeras appear after cleavage intermediates and edited product. Furthermore, a mutant gRNA promotes formation of edited product but not detectable chimeras. Our results suggest a model for kinetoplastid RNA editing in which chimeric molecules are nonproductive end products of editing and not intermediates that serve as a repository for deleted U's.