360 research outputs found
The early socioeconomic effects oftTeenage childbearing
No full textA large body of literature has documented a negative correlation between teenage childbearing and teen mothers' socioeconomic outcomes, yet researchers continue to disagree as to whether the association represents a true causal effect. This article extends the extant literature by employing propensity score matching with a sensitivity analysis using Rosenbaum bounds. The analysis of recent cohort data from the National Longitudinal Study of Adolescent Health shows that (1) teenage childbearing has modest but significant negative effects on early socioeconomic outcomes and (2) unobserved covariates would have to be more powerful than known covariates to nullify the propensity score matching estimates. The author concludes by suggesting that more research should be done to address unobserved heterogeneity and the long-term effects of teenage childbearing for this young cohort.Y
Development of Automobile Seat Comfort Estimation Models based on Polyurethane Foam
No full text22Nkc
Fast and easy detection system of protein glycosylation by using fluorescence resonant energy transfer between nanoparticles
No full textA microfluidic chip for measurement of biomolecules using a microbead-based quantum dot fluorescence assay
No full textThis paper describes a custom-designed microfluidic chip for sensitive detection of antibody using quantum dot fluorescence in a microbead-based assay. The microfluidic chip is designed to isolate a single microbead where the binding reaction of antibodies happens on the surface. The microfluidic chip is fabricated on a glass substrate using transparent silicone elastomer, PDMS, for easy access to monitoring and flexible gate operations to capture the single microbead. For antibody detection, a sequence of functionalized assay has been performed in the fabricated chip including: capturing of microbeads; antibody injection into a micro-chamber; quantum dot injection; and fluorescence detection. Various concentrations of antibody have been tested and have shown good agreement with correlated fluorescent intensities
Multidimensional Adaptive Coefficient for Inference Trajectory Optimization in Flow and Diffusion
No full textMultifunctional microwell plate for on-chip cell and microbead-based bioassays
No full textThis paper reports on a multifunctional microwell plate developed for lab-on-a-chip applications, such as high-throughput cell assay, drug screening, and microbead-based analyses. The proposed device was designed to provide three consecutive functions: the autonomous capture of biomaterials into multiple microwells in a two-dimensional array; active physical sealing of the microwells for isolation; and specific chemical injection into each microwell. The device was implemented with microfabrication technology using polydimethylsiloxane (PDMS) structures on a silicon or glass substrate. The multiple functions of the microwell plate were successfully demonstrated in an experiment using microbeads. The parallel positioning of live cells (CHO DG44) in multiple microwell arrays was achieved, as well as the independent injection of foreign solution into a specific target cell. Also the proposed microwell plate was utilized to capture microbeads, for antibody injection into each microwell, for quantum dot (QD) injection, and for fluorescence detection for a feasible demonstration of a microbead-based assay. (C) 2009 Elsevier B.V. All rights reserved
Kinetic and equilibrium binding analysis of protein-ligand interactions at poly(amidoamine) dendrimer monolayers
No full textThe interaction of streptavidin (SA) with a biotinylated surface has been of great interest in the development of an interfacial layer for protein immobilization based on self-assembled monolayers (SAMs) and polymeric layers. Here, we demonstrate the unique characteristics of protein-ligand interactions on dendrimer monolayers based on kinetic and equilibrium binding analyses. With amine-ended poly(amidoamine) dendrimers from the first (G1) to fourth (G4) generation, the formation of even, compact dendrimer monolayers on gold was confirmed using FT-IR spectroscopy and ellipsometry. For the SA-biotin interaction, quantitative analysis of bound SA using surface plasmon resonance showed that the saturation binding level of SA was fairly higher in all dendrimer layers when compared to other tested systems of 11-mercaptoundecylamine SAMs and a poly(L-lysine) layer. Kinetic studies revealed that the initial binding rate of SA up to the saturation level was 2-fold higher in all dendrimer layers than in the SAMs regardless of the surface density of functionalized biotin. Concurrently, the dendrimer layers led to much higher values of sticking probability, which is defined as the probability that the SA molecule adsorbs upon collision with a biotinylated surface, at a fixed SA coverage, and prolonged the significant levels around the maximum probability with increasing SA coverage. Plots of the saturation coverage of SA versus the SA concentration in solution showed that SA binding onto the biotinylated G1 and G3 layers fit to a Langmuir isotherm model. Taken together, faster binding of SA and highly ordered packing of the molecules seems to be achieved through typical properties of the dendrimer monolayers such as surface distribution of functionalized biotin, surface corrugation, and flexibility of highly branched larger dendrimers, which provides a guideline for the construction and analysis of an interfacial layer in biosensing applications
High performance immunoassay using immobilized enzyme in nanoporous carbon
No full textA highly stable immunoassay format was constructed using signal-generating enzyme immobilized in nanoporous carbon. A mesocellular carbon foam, called MSU-F-C, was loaded with horseradish peroxidase (HRP), followed by cross-linking of the enzyme using glutaraldehyde (GA) and modification of the surface with anti-human IgG through EDC/sulfo-NHS chemistry. The resulting MSU-F-C/HRP/anti-human IgG stably retained immobilized enzymes and antibodies, showing higher thermal stability. The MSU-F-C/HRP/anti-human IgG retained about 80% of initial enzyme activity at 40 degrees C after a 5 h incubation, while the HRP/anti-human IgG conjugate resulted in almost 90% loss of initial activity in the same condition. In bead-based immunoassays, the signal amplification using MSU-F-C/HRP/anti-human IgG enabled the sensitive colorimetric detection of a target analyte, human IgG, in a detection limit of similar to 33 pM, with negligible cross-reactivity against rabbit and chicken IgGs.N
Linking Cell Cycle Reentry and DNA Damage in Neurodegeneration
No full textAberrant cell cycle activity and DNA damage have been observed in neurons in association with various neurodegenerative conditions. While there is strong evidence for a causative role for these events in neurotoxicity, it is unclear how they are triggered and why they are toxic. Here, we introduce a brief background of the current view on cell cycle activity and DNA damage in neurons and speculate on their relevance to neuronal survival. Furthermore, we suggest that the two events may be triggered in common by deregulation of fundamental processes, such as chromatin modulation, which are required for maintaining both DNA integrity and proper regulation of cell cycle gene expression
Multiplexed immunoassay using the stabilized enzymes in mesoporous silica
No full textMultiplexed immunoassay system was developed using the enzyme-immobilized mesoporous silica in a form of nanoscale enzyme reactors (NERs). which improve the enzyme loading, activity, and stability. Glucose oxidase (GO) and trypsin (TR) were adsorbed into mesoporous silica and further crosslinked for the construction of NERs, and antibody-conjugated NERs were employed for the analysis of target antigens in a sandwich-type magnetic bead-based immunoassay. This approach, called as NER-LISA (NER-linked immunosorbent assay), generated signals out of enzyme reactions that correlated well with the concentration of target antigens. The detection limit of NER-LISA using NER-GO and anti-human IgG was 67 pM human IgG, and the sensitivity was 20 times higher than that of the conventional ELISA using anti-human IgG conjugated GO. Antibody-conjugated NER-GO and NER-TR were successfully employed for the simultaneous detection of two target antigens (human IgG and chicken IgG) in a solution by taking advantage of signals at different wavelengths (absorbances at 570 nm and 410 nm, respectively) from the assays of GO and TR activities, demonstrating the potential of NER-LISA in multiplexed immunoassay. The NER-LISA approach also enabled the successful use of a protease (trypsin), because the NER approach can effectively retain the protease molecules within the mesoporous silica and prevent the digestion of antibodies and enzymes during the whole process of NER-LISA. (C) 2009 Elsevier B.V. All rights reserved.N
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