The Influence of Spin-Labeled Fluorene Compounds on the Assembly and Toxicity of the Aβ Peptide

The deposition and oligomerization of amyloid β (Aβ) peptide plays a key role in the pathogenesis of Alzheimer's disease (AD). Aβ peptide arises from cleavage of the membrane-associated domain of the amyloid precursor protein (APP) by β and γ secretases. Several lines of evidence point to the soluble Aβ oligomer (AβO) as the primary neurotoxic species in the etiology of AD. Recently, we have demonstrated that a class of fluorene molecules specifically disrupts the AβO species. Methodology/Principal Findings To achieve a better understanding of the mechanism of action of this disruptive ability, we extend the application of electron paramagnetic resonance (EPR) spectroscopy of site-directed spin labels in the Aβ peptide to investigate the binding and influence of fluorene compounds on AβO structure and dynamics. In addition, we have synthesized a spin-labeled fluorene (SLF) containing a pyrroline nitroxide group that provides both increased cell protection against AβO toxicity and a route to directly observe the binding of the fluorene to the AβO assembly. We also evaluate the ability of fluorenes to target multiple pathological processes involved in the neurodegenerative cascade, such as their ability to block AβO toxicity, scavenge free radicals and diminish the formation of intracellular AβO species. Conclusions Fluorene modified with pyrroline nitroxide may be especially useful in counteracting Aβ peptide toxicity, because they posses both antioxidant properties and the ability to disrupt AβO species

Intraoperative assessment of biliary anatomy for prevention of bile duct injury: a review of current and future patient safety interventions

Background Bile duct injury (BDI) is a dreaded complication of cholecystectomy, often caused by misinterpretation of biliary anatomy. To prevent BDI, techniques have been developed for intraoperative assessment of bile duct anatomy. This article reviews the evidence for the different techniques and discusses their strengths and weaknesses in terms of efficacy, ease, and cost-effectiveness. Method PubMed was searched from January 1980 through December 2009 for articles concerning bile duct visualization techniques for prevention of BDI during laparoscopic cholecystectomy. Results Nine techniques were identified. The critical-view-of-safety approach, indirectly establishing biliary anatomy, is accepted by most guidelines and commentaries as the surgical technique of choice to minimize BDI risk. Intraoperative cholangiography is associated with lower BDI risk (OR 0.67, CI 0.61-0.75). However, it incurs extra costs, prolongs the operative procedure, and may be experienced as cumbersome. An established reliable alternative is laparoscopic ultrasound, but its longer learning curve limits widespread implementation. Easier to perform are cholecystocholangiography and dye cholangiography, but these yield poor-quality images. Light cholangiography, requiring retrograde insertion of an optical fiber into the common bile duct, is too unwieldy for routine use. Experimental techniques are passive infrared cholangiography, hyperspectral cholangiography, and near-infrared fluorescence cholangiography. The latter two are performed noninvasively and provide real-time images. Quantitative data in patients are necessary to further evaluate these techniques. Conclusions The critical-view-of-safety approach should be used during laparoscopic cholecystectomy. Intraoperative cholangiography or laparoscopic ultrasound is recommended to be performed routinely. Hyperspectral cholangiography and near-infrared fluorescence cholangiography are promising novel techniques to prevent BDI and thus increase patient safety

HIV Replication Enhances Production of Free Fatty Acids, Low Density Lipoproteins and Many Key Proteins Involved in Lipid Metabolism: A Proteomics Study

BACKGROUND: HIV-infected patients develop multiple metabolic abnormalities including insulin resistance, lipodystrophy and dyslipidemia. Although progression of these disorders has been associated with the use of various protease inhibitors and other antiretroviral drugs, HIV-infected individuals who have not received these treatments also develop lipid abnormalities albeit to a lesser extent. How HIV alters lipid metabolism in an infected cell and what molecular changes are affected through protein interaction pathways are not well-understood. RESULTS: Since many genetic, epigenetic, dietary and other factors influence lipid metabolism in vivo, we have chosen to study genome-wide changes in the proteomes of a human T-cell line before and after HIV infection in order to circumvent computational problems associated with multiple variables. Four separate experiments were conducted including one that compared 14 different time points over a period of >3 months. By subtractive analyses of protein profiles overtime, several hundred differentially expressed proteins were identified in HIV-infected cells by mass spectrometry and each protein was scrutinized for its biological functions by using various bioinformatics programs. Herein, we report 18 HIV-modulated proteins and their interaction pathways that enhance fatty acid synthesis, increase low density lipoproteins (triglycerides), dysregulate lipid transport, oxidize lipids, and alter cellular lipid metabolism. CONCLUSIONS: We conclude that HIV replication alone (i.e. without any influence of antiviral drugs, or other human genetic factors), can induce novel cellular enzymes and proteins that are significantly associated with biologically relevant processes involved in lipid synthesis, transport and metabolism (p = <0.0002-0.01). Translational and clinical studies on the newly discovered proteins may now shed light on how some of these proteins may be useful for early diagnosis of individuals who might be at high risk for developing lipid-related disorders. The target proteins could then be used for future studies in the development of inhibitors for preventing lipid-metabolic anomalies. This is the first direct evidence that HIV-modulates production of proteins that are significantly involved in disrupting the normal lipid-metabolic pathways