Acetylation of PAMAM dendrimers for cellular delivery of siRNA

<p>Abstract</p> <p>Background</p> <p>The advancement of gene silencing via RNA interference is limited by the lack of effective short interfering RNA (siRNA) delivery vectors. Rational design of polymeric carriers has been complicated by the fact that most chemical modifications affect multiple aspects of the delivery process. In this work, the extent of primary amine acetylation of generation 5 poly(amidoamine) (PAMAM) dendrimers was studied as a modification for the delivery of siRNA to U87 malignant glioma cells.</p> <p>Results</p> <p>PAMAM dendrimers were reacted with acetic anhydride to obtain controlled extents of primary amine acetylation. Acetylated dendrimers were complexed with siRNA, and physical properties of the complexes were studied. Dendrimers with up to 60% of primary amines acetylated formed ~200 nm complexes with siRNA. Increasing amine acetylation resulted in reduced polymer cytotoxicity to U87 cells, as well as enhanced dissociation of dendrimer/siRNA complexes. Acetylation of dendrimers reduced the cellular delivery of siRNA which correlated with a reduction in the buffering capacity of dendrimers upon amine acetylation. Confocal microscopy confirmed that escape from endosomes is a major barrier to siRNA delivery in this system.</p> <p>Conclusion</p> <p>Primary amine acetylation of PAMAM dendrimers reduced their cytotoxicity to U87 cells, and promoted the release of siRNA from dendrimer/siRNA complexes. A modest fraction (approximately 20%) of primary amines of PAMAM can be modified while maintaining the siRNA delivery efficiency of unmodified PAMAM, but higher degrees of amine neutralization reduced the gene silencing efficiency of PAMAM/siRNA delivery vectors.</p

Learning and Education of Marginalized Women in the United States

What do we ‘know’ about marginalized women’s learning and educational experiences and how can this knowledge positively inform educators and researchers? All interested scholars are invited to share their research methodologies, experiences, and findings in this roundtable as we begin to develop a collective understanding

Board of Regents

This report, fifteenth of an annual series, describes 1993 mineral, oil and gas, and geothermal activities and accomplishments in Nevada: production statistics, exploration and development including drilling for petroleum and geothermal resources, discoveries of orebodies, new mines opened, and expansion and other activities of existing mines. Statistics of known gold and silver deposits, and directories of mines and mills are included. For more information contact

Predicting the consumption of foods low in saturated fats among people diagnosed with Type 2 diabetes and cardiovascular disease: the role of planning in the theory of planned behaviour

The present study tested the utility of an extended version of the theory of planned behaviour that included a measure of planning, in the prediction of eating foods low in saturated fats among adults diagnosed with Type 2 diabetes and/or cardiovascular disease Participants (N = 184) completed questionnaires assessing standard theory of planned behaviour measures (attitude, subjective norm, and perceived behavioural control) and the additional volitional variable of planning in relation to eating foods low in saturated fats Self-report consumption of foods low insaturated fats was assessed 1 month later In partial support of the theory of planned behaviour, results indicated that attitude and subjective norm predicted intentions to eat foods low in saturated fats and intentions and perceived behavioural control predicted the consumption of foods low in saturated fats As an additional variable, planning predicted the consumption of foods low in saturated fats directly and also mediated the intention-behaviour and perceived behavioural control-behaviour relationships, suggesting an important role for planning as a post-intentional construct determining healthy eating choices. Suggestions are offered for interventions designed to improve adherence to healthy eating recommendations for people diagnosed with these chronic conditions with a specific emphasis on the steps and activities that are required to promote a healthier lifestyle. (C) 2010 Elsevier Ltd. All rights reserve

Reduced risk of incident AD with elective statin use in a clinical trial cohort

Statins have been reported to reduce the risk and be of benefit in the treatment of Alzheimer\u27s disease (AD). Individuals enrolling in the randomized controlled trial testing two anti-inflammatory agents for primary prevention of AD (Alzheimer\u27s Disease Anti-inflammatory Prevention Trial; ADAPT) were allowed the elective use of statins. Our objective was to assess whether statin use is associated with reduced risk of incident AD among ADAPT participants. In primary ADAPT study , participants were assessed annually for cholesterol levels and cognitive status. If impairment in cognition was noted, a dementia evaluation was performed. Onset of mild cognitive impairment (MCI) or AD was taken as the date of this evaluation. Time-to-onset was analyzed in six-month intervals following enrollment. Without knowledge of primary treatment assignment in ADAPT, participants were grouped by their self-reported use of lipid-lowering agents (LLA). In the current ancillary ADAPT study we found that elective statin use was associated with significantly reduced risk of incident AD after adjustment for age, gender, education and Apolipoprotein E (ApoE) genotype. The findings were similar when comparing all LLA use (statin and non-statin LLA) to non-LLA use. Cholesterol levels were lower among statin users compared with non-LLA users, but the MMSE scores were equivalent. The data suggest that statin therapy may be of benefit in reducing the risk of AD. ©2008 Bentham Science Publishers Ltd

Cholesterol and Cognitive Performance in Normal Controls and the Influence of Elective Statin Use after Conversion to Mild Cognitive Impairment: Results in a Clinical Trial Cohort

Background: We reported a significant 67% reduction in the hazard risk of incident Alzheimer\u27s disease (AD) with elective statin use in the AD Anti-inflammatory Prevention Trial (ADAPT), without a reduction in risk of incident mild cognitive impairment (MCI). Objective: To assess if cholesterol levels are associated with cognitive performance and determine if statin use alters cognitive performance after onset of MCI. Design: Fractionated cholesterol levels, neurological and cognitive status were evaluated annually. Comparisons of non-LLA (lipid-lowering agent) users or statin-LLA users were performed blind to the ADAPT medication randomization. Pearson\u27s correlations were validated using a time-dependent linear mixed model. Results: The MMSE performance significantly declined over time in non-LLA users, and, after adjusting for this, a significant positive correlation between MMSE and HDL was identified (p = 0.0002). A negative correlation between total and LDL cholesterol, and immediate and delayed recall of the Rivermead paragraph was significant (total cholesterol, p \u3c 0.003; LDL, p \u3c 0.02). Pilot data suggest a positive signal on delayed recall of both the Hopkins word list and Rivermead paragraph with deterioration in the non-LLA users and improvement in the statin users after conversion to MCI. Conclusion: Cholesterol levels may be associated with differential performance on the MMSE and measures of learning or memory. The trend for improved delayed recall in statin users with MCI compared to non-LLA users with MCI may have contributed to the reduced hazards risk of incident AD without reducing the risk of MCI. Copyright © 2010 S. Karger AG, Basel

Tau is reduced in AD plasma and validation of employed ELISA methods

Objective: Measure total tau levels in the circulation of living humans, validate the methods employed and determine if there are consistent differences in total tau levels between normal controls and individuals with mild cognitive impairment (MCI) and/or Alzheimer\u27s disease (AD). Methods: Employing ELISA methods, validated by Western bolts using three separate tau antibodies, we quantified total tau levels in serially collected serum and plasma samples from individuals longitudinally evaluated for cognitive performance. Results: We identified substantial levels of tau in human circulation using plasma, but not serum. The measurement of authentic tau protein was verified by Western blots using a C-terminal specific antibody, an N-terminal specific antibody and antibody used in the commercially available ELISA kit. We revealed a significant decrease in plasma levels of total tau among subjects with MCI compared to cognitively normal controls, with a further highly significant reduction in AD patients compared to both MCI and normal controls. We also found a significant positive correlation between changing levels of plasma tau and cognitive performance within the entire population and among AD patients. Conclusions: The data suggest that changes in circulating tau levels quantified in plasma samples, but not serum samples, may represent a viable bio-marker for tracking the progression of AD and the efficacy of medications in its treatment

The Northern Black Swift: Migration path and wintering area revealed

Winter ranges have been identified for most neotropical migrant bird species, those that spend the winter months in Central and South America and summer months in North America. Published accounts and specimen collections of the Northern Black Swift (Cypseloides niger borealis) during spring and fall migration are extremely limited and winter records are nonexistent. We placed light-level geolocators on four Black Swifts in August 2009, and retrieved three a year later. Data from the geolocators revealed initiation of fall migration (10 to 19 Sep 2009), arrival dates at wintering areas (28 Sep to 12 Oct 2009), departure dates from wintering areas (9 to 20 May 2010), and return dates to breeding sites (23 May to 18 Jun 2010) for Northern Black Swifts breeding in interior North America (Colorado, USA). Northern Black Swifts traveled 6,901 km from the Box Canyon breeding site and 7,025 km from Fulton Resurgence Cave to the center of the wintering area. The swifts traveled at an average speed of 341 km/day during the 2009 fall migration and an average speed of 393 km/day during the 2010 spring migration. This is the first evidence that western Brazil is the wintering area for a subset of the Northern Black Swift, extending the known winter distribution of this species to South America