MicroRNA Detection by DNA‐Mediated Liposome Fusion

Membrane fusion is a process of fundamental importance in biological systems that involves highly selective recognition mechanisms for the trafficking of molecular and ionic cargos. Mimicking natural membrane fusion mechanisms for the purpose of biosensor development holds great potential for amplified detection because relatively few highly discriminating targets lead to fusion and an accompanied engagement of a large payload of signal‐generating molecules. In this work, sequence‐specific DNA‐mediated liposome fusion is used for the highly selective detection of microRNA. The detection of miR‐29a, a known flu biomarker, is demonstrated down to 18 nm within 30 min with high specificity by using a standard laboratory microplate reader. Furthermore, one order of magnitude improvement in the limit of detection is demonstrated by using a novel imaging technique combined with an intensity fluctuation analysis, which is coined two‐color fluorescence correlation microscopy.     

Auxetic Cardiac Patches with Tunable Mechanical and Conductive Properties toward Treating Myocardial Infarction

An auxetic conductive cardiac patch (AuxCP) for the treatment of myocardial infarction (MI) is introduced. The auxetic design gives the patch a negative Poisson's ratio, providing it with the ability to conform to the demanding mechanics of the heart. The conductivity allows the patch to interface with electroresponsive tissues such as the heart. Excimer laser microablation is used to micropattern a re‐entrant honeycomb (bow‐tie) design into a chitosan‐polyaniline composite. It is shown that the bow‐tie design can produce patches with a wide range in mechanical strength and anisotropy, which can be tuned to match native heart tissue. Further, the auxetic patches are conductive and cytocompatible with murine neonatal cardiomyocytes in vitro. Ex vivo studies demonstrate that the auxetic patches have no detrimental effect on the electrophysiology of both healthy and MI rat hearts and conform better to native heart movements than unpatterned patches of the same material. Finally, the AuxCP applied in a rat MI model results in no detrimental effect on cardiac function and negligible fibrotic response after two weeks in vivo. This approach represents a versatile and robust platform for cardiac biomaterial design and could therefore lead to a promising treatment for MI.     

Hyaluronic Acid‐Based Hydrogels Enable Rod Photoreceptor Survival and Maturation In Vitro through Activation of the mTOR Pathway

The culture of isolated photoreceptors in vitro has remained elusive in ­neuroscience. By using defined hyaluronic acid (HA) hydrogels, photo­receptor survival and maturation in vitro is dramatically increased, as evidenced by upregulation of outer segment markers at the RNA and protein levels. While substrate stiffness is known to be a key factor influencing cell survival in vitro, it is shown that isolated photoreceptors do not respond to modifications in hydrogel stiffness modifications but depend, instead, on HA for survival. While the molecular pathways that are induced by HA on photoreceptors are unknown, mTOR activation is identified as the molecular mechanism underlying the pro‐survival effect, and it is demonstrated that the canonical Wnt and RhoA pathways are intermediaries. This work establishes a valuable method for isolated photoreceptor culture in vitro, which will be useful in translational and basic retinal research. The pathways identified herein may be useful targets in retinal degeneration.     

Impulsive choice and altruistic punishment are correlated and increase in tandem with serotonin depletion.

Human cooperation may partly depend on the presence of individuals willing to incur personal costs to punish noncooperators. The psychological factors that motivate such 'altruistic punishment' are not fully understood; some have argued that altruistic punishment is a deliberate act of norm enforcement that requires self-control, while others claim that it is an impulsive act driven primarily by emotion. In the current study, we addressed this question by examining the relationship between impulsive choice and altruistic punishment in the ultimatum game. As the neurotransmitter serotonin has been implicated in both impulsive choice and altruistic punishment, we investigated the effects of manipulating serotonin on both measures. Across individuals, impulsive choice and altruistic punishment were correlated and increased following serotonin depletion. These findings imply that altruistic punishment reflects the absence rather than the presence of self control, and suggest that impulsive choice and altruistic punishment share common neural mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distribution and Transport of Fecal Bacteria at Spring Thaw in a Rural Alaskan Community

People living without piped water and sewer can be at increased risk for diseases transmitted by the fecal-oral route. One Alaskan community that relies on hauled water and sewage was studied to determine the pathways of fecal contamination of drinking water and the human environment so that barriers can be established to protect human health. Samples were tested for the fecal indicators Escherichia coli and Enterococcus. Several samples were tested for the pathogens Giardia lamblia and Cryptosporidium parvum and source tracking methods were employed. Surface water flow transported bacteria within the community during spring thaw and human fecal contamination was detected in town, but flow from the dump did not appear to contribute to contamination in town. Within the home, fecal bacteria were found on water dippers, kitchen counters and floors, and in hand-washing basins. Giardia was found at the dump, but not in water from the river adjacent to the community. Exposure to fecal contamination could be reduced by cleaning up after dogs, carefully disposing of wastewater, and by protecting stored drinking water.     

Molecular Structure of Binary Chromium(III)–DNA Adducts

Chromium(VI) is a carcinogen and mutagen, and its mechanisms of action are proposed to involve binding of its reduction product, chromium(III), to DNA. The manner in which chromium(III) binds DNA has not been established, particularly at a molecular level. Analysis of oligonucleotide duplex DNAs by NMR, EPR, and IR spectroscopies in the presence of chromium(III) allows the elucidation of the Cr binding site. The metal centers were found to interact exclusively with guanine N7 positions. No evidence of chromium interactions with other bases or backbone phosphates nor of Cr forming intra-strand crosslinks between neighboring guanine residues was observed.     

Noncontact Methods for Measuring Thermal Barrier Coating Temperatures

Three noncontact, optical methods for measuring temperature are reviewed with an emphasis on their application to the measurement of temperatures of thermal barrier coatings (TBCs). The methods are: infrared pyrometry, Raman spectroscopy, and photo-stimulated luminescence from lanthanide-doped coatings. Although each has the capability of measuring temperatures pertinent to monitoring TBCs, the finite thickness of typical coatings together with the optical properties of zirconia place severe restrictions on the depth from which the temperature sensing can be obtained. Some of these limitations can be circumvented using photo-stimulated luminescence with coatings containing dopants at specific locations. To illustrate this, it is demonstrated that by depositing coatings with a lanthanide dopant, such as Eu³⁺, at specific locations, for instance in contact with the metallic alloy, temperature sensing can be performed with much higher spatial resolution.     

Anhedonia associated with stimulant use and dependence in a population-based sample of American adults.

Prior research suggests an association between anhedonia—diminished interest or pleasure in rewarding activities—and stimulant use in selected samples. However, it is unclear whether this association generalizes to the overall population and is consistent across stimulant drug types (amphetamine vs. cocaine) and outcome characteristics (any lifetime use vs. dependence). Questions also remain as to whether the anhedonia–stimulant relationship is unique from covariance with depressed mood, psychiatric disorders, and nonstimulant substance use. The current study addressed these questions by examining anhedonia–stimulant relationships in a cross-sectional population-based sample of 43,093 American adults. Results indicated that lifetime anhedonia and depressed mood each were positively associated with lifetime stimulant use and lifetime dependence among those who reported stimulant use. Anhedonia–stimulant relationships were consistent across amphetamine- and cocaine-related outcomes and distinct from covariance with depressed mood, which exhibited no association over and above the effect of anhedonia. After adjusting for demographic, psychiatric, and nonstimulant substance use characteristics, anhedonia–stimulant associations remained significant, although effect sizes were partially attenuated. Lifetime anhedonia was also more prevalent among respondents who initiated use but did not eventually progress to dependence in comparison with individuals who never once used a stimulant drug. Anhedonia appears to be uniquely associated with lifetime use of cocaine and amphetamines and lifetime progression from use to dependence in the American population. Albeit cross-sectional in nature, these findings add further support to the generalizability and specificity of the anhedonia–stimulant relationship. Future research utilizing longitudinal and experimental designs are warranted to clarify the underpinnings of this association. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using modified soy protein to enhance foaming of egg white protein

BACKGROUND: It is well known that the foaming properties of egg white protein are significantly reduced when a small amount of yolk is mixed in the white. To improve foaming properties of yolk‐contaminated egg white protein, soy protein isolate (SPI) and egg proteins were modified to make basic proteins, and effects of these modified proteins on egg white foaming were evaluated in a model and an angel cake system. RESULTS: SPI and egg yolk proteins were modified to have an isoelectric point of 10, and sonication was used to increase protein dispersibility after the ethyl esterification reaction. However, only the addition of sonicated and modified SPI (SMSPI) showed improvement of foaming in the 5% egg protein model system with 0.4% yolk addition. SMSPI was then used in making angel food cake to examine whether the cake performance reduction due to yolk contamination of the white would be restored by such alkaline protein. Cake performance was improved when cream of tartar was used together with SMSPI. CONCLUSION: Basic soy protein can be made and used to improve egg white foaming properties and cake performance. Copyright © 2012 Society of Chemical Industry