PubMed · 11315495
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
M Max. 2001. [PEEP].. https://doi.org/10.1007/s001010050990
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Transfection and subsequent expression of DNA in living neuronal tissue is problematic and no technique has emerged that is completely non-damaging, efficient and reproducible. The Bio-Rad hand-held Gene Gun has overcome some of these problems by exploiting a biolistic method in which small gold particles carrying plasmid DNA are propelled into neurons whilst causing minimal detectable cell damage. In its current configuration, however, the Bio-Rad Gene Gun is optimised for transfecting cells in dispersed cultures, and therefore delivers particles superficially over a relatively wide area. Here we report modifications to the Bio-Rad Gene Gun that both enhance its accuracy by restricting its target area, and increase the depth penetration achieved by gold particles, thereby allowing smaller and deeper tissues to be transfected. These alterations make the modified Gene Gun more applicable for in vitro transfection of organotypic cultures and enhance its potential utility for in vivo gene delivery. Moreover, the modified configuration operates successfully at lower gas pressures, thereby reducing even further the degree of cell damage incurred during transfection.
OBJECTIVE: Verbal instruction and demonstration of inhalation technique are essential to enhance the effectiveness of inhalation therapy. Placebo devices are commonly used to instruct patients. It is not obvious that patients, who inhale with an adequate flow through an empty placebo Diskus, would also be able to do so with active inhalers containing a strip with powder. The presence of powder may result in a change in resistivity. We compared the resistivities of a placebo Diskus being empty; a powder filled Diskus inhaler and a Diskus inhaler with an empty blister. METHODS: A Diskus inhaler was placed in a box, which enabled measurement of pressure drop and flow rates. Ten placebo and ten Ventolin Diskus inhalers were measured. Twelve pressure- and flow-profiles were recorded through each device. After each simulated inhalation through a powder filled blister, a second inhalation was performed through the empty blister. The resistivity was calculated by pressure-flow equation. RESULTS: The resistivity of the empty placebo Diskus inhaler was slightly but significantly higher than both blister filled inhalers, with or without powder (0.0215 vs. 0.0211 and 0.0211 (kPa)(0.5) (l min(-1))(-1)) (P<0.001). CONCLUSION: Patients who are capable of generating sufficient flow through a placebo Diskus will surely be capable of generating equivalent flows through a Diskus inhaler containing a strip with active drug substance.
Desensitization of neuronal nicotinic acetylcholine receptors (nAChRs) can develop so rapidly to preclude functional studies when agonists are applied under steady-state conditions. To minimize receptor desensitization, we recorded from rat cultured chromaffin cells currents evoked by nicotine applied by pressure (via a fine tipped pipette) or through a multibarreled rapid solution exchanger. By comparing equi-amplitude, non-fading responses on the same cells, we constructed log 'dose'-response curves with the amount of nicotine expressed as either pulse duration (ms) or initial concentration (microM) inside the perfusion tubes. The linear part of these plots (10-50 ms or 20-100 microM) allowed extrapolating the initial nicotine concentration for a certain pulse duration within these limits. Potential dilution of nicotine in the bath was calculated with diffusion equations for a continuous point source: the maximal concentration of nicotine attainable by pressure application from a 100 microM containing pipette was 92 microM. We also calculated how diluted the same nicotine solution became following rapid superfusion and found it to be 46%. These results indicate that the amount of agonist applied by pressure to a relatively close cell could be calibrated in terms of effective concentration at membrane level and, with the present experimental arrangement, underwent limited dilution in the extracellular microenvironment.