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

Unagreement is an illusion

This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s11049-015-9311-yThis paper proposes an analysis of unagreement, a phenomenon involving an apparent mismatch between a definite third person plural subject and first or second person plural subject agreement observed in various null subject languages (e.g. Spanish, Modern Greek and Bulgarian), but notoriously absent in others (e.g. Italian, European Portuguese). A cross-linguistic correlation between unagreement and the structure of adnominal pronoun constructions suggests that the availability of unagreement depends on whether person and definiteness are hosted by separate heads (in languages like Greek) or bundled on a single head (i.e. pronominal determiners in languages like Italian). Null spell-out of the head hosting person features high in the extended nominal projection of the subject leads to unagreement. The lack of unagreement in languages with pronominal determiners results from the interaction of their syntactic structure with the properties of the vocabulary items realising the head encoding both person and definiteness. The analysis provides a principled explanation for the cross-linguistic distribution of unagreement and suggests a unified framework for deriving unagreement, adnominal pronoun constructions, personal pronouns and pro

Integrating Optical Fiber Bridges in Microfluidic Devices to Create Multiple Excitation/Detection Points for Single Cell Analysis

A microfluidic device is reported that employs an out-of-plane optical fiber bridge to generate two excitation and two detection spots in a microfluidic channel using only one excitation source and one detector. This fiber optic bridge was integrated into a single cell analysis device to detect an intact cell just prior to lysis and the injected lysate 2, 5, 10, or 15 mm downstream of the injection point. Using this setup the absolute migration times for analytes from cells stochastically entering the lysis intersection could be determined for the first time in an automated fashion. This allowed the evaluation of several separation parameters, including analyte band velocity, migration time drift, diffusion coefficient, injection plug length, separation efficiency (<i>N</i>), and plate height (<i>H</i>), which previously could only be estimated. To demonstrate the utility of this system, a peptide substrate for protein kinase B (PKB) was designed, synthesized, and loaded into T-lymphocytes in order to measure PKB activity in individual cells. The optical fiber bridge is easy to implement, inexpensive, and flexible in terms of changing the distances between the two detection points

Pupil diameter as implicit measure to estimate sense of embodiment

We explore pupil diameter (PD) as estimator of Sense of Embodiment (SoE) using data of three user studies. We hypothesize that pupil diameter reflects SoE in a direct and indirect way. If individuals feel strongly embodied, presenting an emotional stimulus like a threat to the surrogate will produce a strong response, as if the stimulus would be presented to their own body. This would lead to a positive correlation between SoE and pupil dilation during the presentation of emotional stimuli. Besides this direct effect, there may also be an indirect effect. It is postulated that higher degrees of embodiment reduce workload when controlling a surrogate. This indirect effect of embodiment through lower workload on the PD would result in a negative correlation between SoE and PD since lower workload results in smaller PD. These direct and indirect effects were partially confirmed by the results of three experiments. We observed that PD and SoE are positive and direct correlated in case of emotional stimuli subjected to the surrogate (e.g. a threat), and that PD tended to be smaller for participants who experienced a condition designed to provide high SoE compared to one designed to provide low SoE

Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study One Year After Surgery

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between −2.00 and −8.00 diopters. The surgical technique consisted of eight incisions using a diamond micrometer knife with blade length determined by intraoperative ultrasonic pachymetry and the diameter of central clear zone determined by preoperative refraction. At one year after surgery, myopia was reduced in all eyes; 60% were within ±1.00 diopter of emmetropia; 30% were undercorrected and 10% were overcorrected by more than 1.00 diopter (range of refraction, −4.25 to +3.38 D). Uncorrected visual acuity was 20/40 or better in 78% of eyes. The operation was most effective in eyes with a refraction between −2.00 and −4.25 diopters. Thirteen percent of patients lost one or two Snellen lines of best corrected visual acuity. However, all but three eyes could be corrected to 20/20. Ten percent of patients increased astigmatism more than 1.00 diopter. Disabling glare was not detected with a clinical glare tester, but three patients reduced their driving at night because of glare. Between six months and one year, the refraction changed by >0.50 diopters in 19% of eyes