Nanochannel electroporation delivers precise amounts of biomolecules into living cells

Many transfection techniques can deliver biomolecules into cells, but the dose cannot be controlled precisely. Delivering well-defined amounts of materials into cells is important for various biological studies and therapeutic applications. Here, we show that nanochannel electroporation can deliver precise amounts of a variety of transfection agents into living cells. The device consists of two microchannels connected by a nanochannel. The cell to be transfected is positioned in one microchannel using optical tweezers, and the transfection agent is located in the second microchannel. Delivering a voltage pulse between the microchannels produces an intense electric field over a very small area on the cell membrane, allowing a precise amount of transfection agent to be electrophoretically driven through the nanochannel, the cell membrane and into the cell cytoplasm, without affecting cell viability. Dose control is achieved by adjusting the duration and number of pulses. The nanochannel electroporation device is expected to have high-throughput delivery applications.     

Electroporation dependence on cell size: optical tweezers study

Electropermeabilization or electroporation is the electrical disruption of a cell's membrane to introduce drugs, DNA/RNA, proteins, or other therapies into the cell. Despite four decades of study, the fundamental science of the process remains poorly understood and controversial. We measured the minimum applied electric field required for permeabilization of suspended spherical cells as a function of the cell radius for three cell lines. Key to this work is our use of optical tweezers to precisely position individual cells and enable well-defined, repeatable measurements on cells in suspension. Our findings call into question fundamental assumptions common to all theoretical treatments that we know of. It is generally expected that, for individual cells from a particular cell line, large cells should be easier to electroporate than small ones: the minimum electric field to cause electropermeabilization should scale inversely with the cell diameter. We found instead that each cell line has its own characteristic field that will, on average, cause permeabilization in cells of that line. Electropermeabilization is a stochastic process: two cells which appear identical may have different permeabilization thresholds. However, for all three cell lines, we found that the minimum permeabilization field for any given cell does not depend on its size.     

Gene transfection of mammalian cells using membrane sandwich electroporation

To avoid safety issues such as immune response and cytotoxicity associated with viruses and liposomes, physical methods have been widely used for either in vivo or ex vivo gene delivery. They are, however, very invasive and often provide limited efficiency. Using pEGFP and pSEAP plasmids and NIH 3T3 fibroblasts as models, we demonstrate a new electroporation-based gene delivery method, called membrane sandwich electroporation (MSE). The MSE method is able to provide better gene confinement near the cell surface to facilitate gene transport into the cells and thus shows significant improvement over transgene expression of mammalian cells compared to current electroporation techniques.     

Exposure therapy for posttraumatic stress disorder in a residential substance use treatment facility.

Clinical lore abounds when discussing the issue of treating trauma-related symptoms in substance-dependent clients. Historically, clinicians have wondered whether they should wait until the client has gained substantial abstinence from abused substances before initiating trauma treatment or if trauma treatment should be conducted during substance use treatment. Furthermore, questions arise with regard to exactly how trauma-related symptoms should be addressed and how trauma treatment should be incorporated into the recovery process. In this article, the growing literature suggesting that posttraumatic stress disorder (PTSD) can be treated concurrently with substance use disorders is reviewed. In addition, the unique challenges of implementing treatment for PTSD with substance-dependent clients seeking treatment in a residential treatment facility are discussed. Specifically, we provide concrete suggestions about how to utilize prolonged exposure, a very effective treatment for PTSD, with clients in a residential substance use treatment facility, including use of the internet to facilitate exposure therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental patterns of heart rate and variability in prematurely-born infants with apnea of prematurity

At equivalent post-conceptional ages, prematurely-born infants have higher heart rates and reduced heart rate variability, relative to full-term neonates. Premature birth might exert long-lasting effects on central and peripheral mechanisms that control cardiovascular activity. We assessed development of heart rate and heart rate variability in symptomatic preterm infants up to 6 months of age. Fifty 6.5-h evening recordings of EKG and breathing were obtained from prematurely-born infants (gestational ages: 24-35 weeks). Cardiac R-R intervals were captured with a resolution of +/- 0.5 msec. One-min epochs were selected from three periods of regular respiration in recordings from premature infants and 72 recordings of full-term infants at comparable post-conceptional ages. Mean heart rate and heart rate variability were determined for each recording. At 40 weeks post-conception, prematurely-born infants with apnea of prematurity showed higher heart rates and reduced heart rate variability than did full-term neonates. These differences between premature and full-term infants persisted throughout the next 6 months in those infants born prior to 30 weeks gestation, and in those infants born at 30-35 weeks who experienced respiratory distress syndrome (RDS) during the neonatal period. The findings suggest that premature delivery, or complications thereof, exerts long-lasting effects on cardiac control.     

Craving and physiological reactivity to trauma and alcohol cues in posttraumatic stress disorder and alcohol dependence.

The high comorbidity of posttraumatic stress disorder (PTSD) and alcohol dependence (AD) has been firmly established. Although laboratory studies have examined self-reported craving in response to trauma and alcohol cues, no studies have reported on alcohol-related physiological responding in response to trauma cues in PTSD-AD individuals. Using a cue reactivity paradigm, this study examined the impact of personalized trauma-image cues and in vivo alcohol cues on alcohol-related responding (e.g., salivation, craving) in individuals with PTSD and AD (n = 40). Participants displayed reactivity to both trauma and alcohol cues when compared to neutral cues, including increased self-reported craving and distress, as well as greater salivation. These findings suggest that through repeated pairings of trauma memories and alcohol consumption, salivation may become classically conditioned to trauma cues. Moreover, the fact that the trauma-alcohol cue combination elicited greater alcohol craving, salivary responding, distress, and arousal than either the trauma-neutral or neutral-alcohol cue combinations suggests that effects of the trauma and alcohol cues were additive in nature. Evidence that AD individuals with PTSD report increased alcohol craving and display greater salivation in response to trauma memories, supplements prior research indicating that PTSD-related negative emotion and trauma-related alcohol craving may play an important role in the maintenance of AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)