An Integrated Microfluidic Device for Monitoring Changes in Nitric Oxide Production in Single T-Lymphocyte (Jurkat) Cells

A considerable amount of attention has been focused on the analysis of single cells in an effort to better understand cell heterogeneity in cancer and neurodegenerative diseases. Although microfluidic devices have several advantages for single cell analysis, few papers have actually demonstrated the ability of these devices to monitor chemical changes in perturbed biological systems. In this paper, a new microfluidic channel manifold is described that integrates cell transport, lysis, injection, electrophoretic separation, and fluorescence detection into a single device, making it possible to analyze individual cells at a rate of 10 cells/min in an automated fashion. The system was employed to measure nitric oxide (NO) production in single T-lymphocytes (Jurkat cells) using a fluorescent marker, 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA). The cells were also labeled with 6-carboxyfluorescein diacetate (6-CFDA) as an internal standard. The NO production by control cells was compared to that of cells stimulated using lipopolysaccharide (LPS), which is known to cause the expression of inducible nitric oxide synthase (iNOS) in immune-type cells. Statistical analysis of the resulting electropherograms from a population of cells indicated a twofold increase in NO production in the induced cells. These results compare nicely to a recently published bulk cell analysis of NO

Evaluation of the intrinsic kinetic activity of nanoparticle ensembles under steady-state conditions

We report theory and strategies for evaluating the intrinsic kinetic activity for oxygen reduction at Pt nanoparticle (NP) ensembles on a large glassy carbon electrode (GCE) under steady-state conditions. Pt NPs were synthesized using reverse microemulsions which facilitated the deposition of random ensembles of bare NPs with controlled NP mean size and coverage. Steady-state voltammograms (SSVs) for oxygen reduction were recorded for various NP ensembles with different NP size and coverage. The effects of NP coverage and mass-transport rate on SSV features were analyzed. For SSVs normalized with respect to their limiting current, more negative potentials are needed to reach the limiting current region and the i–E slope decreases as NP coverage decreases. For those normalized SSVs having unequal limiting currents, the kinetic rate relative to the mass-transport rate changes and plays a role in the decreasing steepness of the SSV. In contrast, normalized SSVs recorded under the same mass transport conditions and decreasing NP coverage are displaced negatively along the potential axis without a change in the i–E slope. Normalized SSVs recorded using the same mass transport conditions on electrodes with similar fractions of inactive area but different NP sizes were found to be similar. Tafel plots were constructed by processing the SSVs either directly through the use of the electroactive surface area AES or indirectly through a two-step procedure that uses the geometric surface area where an apparent potential-dependent kinetic current density j app K (E) is first calculated. These two approaches are equivalent and the resulting kinetic current density jK(E) dependencies were shown to be equivalent. The direct method is applicable when AES can be determined whereas the indirect approach is useful when the measurement of AEAS is not possible, but information relating to the fraction of active or inactive area is available.Fil: Zoski, Cynthia G.. New Mexico State University. Department of Chemistry and Biochemistry; Estados UnidosFil: Fernandez, Jose Luis. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Electroquímica Aplicada e Ingeniería Electroquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; Argentina. New Mexico State University. Department of Chemistry and Biochemistry; Estados UnidosFil: Imaduwage, Kasun. New Mexico State University. Department of Chemistry and Biochemistry; Estados UnidosFil: Gunasekara, Dulan. New Mexico State University. Department of Chemistry and Biochemistry; Estados UnidosFil: Vadari, Raghuveer. New Mexico State University. Department of Chemistry and Biochemistry; Estados Unido

Robotic technology results in faster and more robust surgical skill acquisition than traditional laparoscopy

Technical surgical skills are said to be acquired quicker on a robotic rather than laparoscopic platform. However, research examining this proposition is scarce. Thus, this study aimed to compare the performance and learning curves of novices acquiring skills using a robotic or laparoscopic system, and to examine if any learning advantages were maintained over time and transferred to more difficult and stressful tasks. Forty novice participants were randomly assigned to either a robotic- or laparoscopic-trained group. Following one baseline trial on a ball pick-and-drop task, participants performed 50 learning trials. Participants then completed an immediate retention trial and a transfer trial on a two-instrument rope-threading task. One month later, participants performed a delayed retention trial and a stressful multi-tasking trial. The results revealed that the robotic-trained group completed the ball pick-and-drop task more quickly and accurately than the laparoscopic-trained group across baseline, immediate retention, and delayed retention trials. Furthermore, the robotic-trained group displayed a shorter learning curve for accuracy. The robotic-trained group also performed the more complex rope-threading and stressful multi-tasking transfer trials better. Finally, in the multi-tasking trial, the robotic-trained group made fewer tone counting errors. The results highlight the benefits of using robotic technology for the acquisition of technical surgical skills