Search results for "Assay"

Immobilisation increases yeast cells' resistance to dehydration-rehydration treatment.

2014

This study was performed with the goal of revealing if the dehydration procedure used in our new immobilisation method noticeably decreases the viability of yeast cells in immobilised preparations. Various yeasts were used in this research: Saccharomyces cerevisiae cells that were rather sensitive to dehydration and had been aerobically grown in an ethanol-containing medium, a recombinant strain of S. cerevisiae grown in aerobic conditions which were completely non-resistant to dehydration and an anaerobically grown bakers' yeast strain S. cerevisiae, as well as a fairly resistant Pichia pastoris strain. Experiments performed showed that immobilisation of all these strains essentially incre…

Real time optical immunosensing with flow-through porous alumina membranes

2014

Through the presentation of analytical data from bioassay experiments, measured by polarimetry, we demonstrate for the first time a real time immunoassay within a free standing macroporous alumina membrane. The 200 nm nominal pore diameter of the membrane enables flow-through, thereby providing an ideal fluidic platform for the targeted delivery of analytes to bioreceptors immobilized on the pore walls, enabling fast sensing response times and the use of small sample volumes (<100 mu L). For the immunoassay, the pore walls were first coated with the functional copolymer, copoly(DMA-NAS) using a novel coupling process, before immobilization of the allergen protein, beta-lactoglobulin, by spo…

Production of Hev b5 as a fluorescent biotin-binding tripartite fusion protein in insect cells

2005

The presented green fluorescent protein and streptavidin core-based tripartite fusion system provides a simple and efficient way for the production of proteins fused to it in insect cells. This fusion protein forms a unique tag, which serves as a multipurpose device enabling easy optimization of production, one-step purification via streptavidin-biotin interaction, and visualization of the fusion protein during downstream processing and in applications. In the present study, we demonstrate the successful production, purification, and detection of a natural rubber latex allergen Hev b5 with this system. We also describe the production of another NRL allergen with the system, Hev b1, which fo…

Mutation of a critical tryptophan to lysine in avidin or streptavidin may explain why sea urchin fibropellin adopts an avidin-like domain

1999

Sea urchin fibropellins are epidermal growth factor homologues that harbor a C-terminal domain, similar in sequence to hen egg-white avidin and bacterial streptavidin. The fibropellin sequence was used as a conceptual template for mutation of designated conserved tryptophan residues in the biotin-binding sites of the tetrameric proteins, avidin and streptavidin. Three different mutations of avidin, Trp-110-Lys, Trp-70-Arg and the double mutant, were expressed in a baculovirus-infected insect cell system. A mutant of streptavidin, Trp-120-Lys, was similarly expressed. The homologous tryptophan to lysine (W--K) mutations of avidin and streptavidin were both capable of binding biotin and bioti…

The influence of bone allograft processing on osteoblast attachment and function

2004

In order to assess the influence of eight different sterilisation and disinfection methods for bone allografts on adhesion, proliferation, and differentiation of human bone marrow stromal cells (BMSC), cells were grown in culture and then plated onto pieces of human bone allografts. Following processing methods were tested: autoclavation (AUT), low-temperature-plasma sterilisation of demineralised allografts (D-LTP), ethylene oxide sterilisation (EtO), fresh frozen bone (FFB), 80 degrees C-thermodisinfection (80 degrees C), gamma-irradiation (Gamma), chemical solvent disinfection (CSD), and Barrycidal-disinfection (BAR). The seeding efficiency was determined after one hour to detect the num…

Multicellular tumor spheroids: an underestimated tool is catching up again.

2009

The present article highlights the rationale, potential and flexibility of tumor spheroid mono- and cocultures for implementation into state of the art anti-cancer therapy test platforms. Unlike classical monolayer-based models, spheroids strikingly mirror the 3D cellular context and therapeutically relevant pathophysiological gradients of in vivo tumors. Some concepts for standardization and automation of spheroid culturing, monitoring and analysis are discussed, and the challenges to define the most convenient analytical endpoints for therapy testing are outlined. The potential of spheroids to contribute to either the elimination of poor drug candidates at the pre-animal and pre-clinical …

Inhibition of B2 receptor internalization delays its dephosphorylation

1997

Fructooligosaccharide and levan producing activity of Zymomonas mobilis extracellular levansucrase

2002

Abstract The present work was devoted to investigations of the fructooligosaccharide (FOS) and levan forming activity of ethanol producing bacteria Zymomonas mobilis and their extracellular levansucrase. After cell separation the culture liquid was treated with ethanol to precipitate levan together with extracellular levansucrase. Levan–levansucrase sediment can be used as biocatalyst for fructooligosaccharide (FOS) production in sucrose syrup and levan sediment as soluble fibre source. The dynamics of sucrose conversion and glucose, fructose, and FOS formation by extracellular levansucrase showed that the fructose content increased only during the first 6 h, while the glucose content conti…

Machine learning for a combined electroencephalographic anesthesia index to detect awareness under anesthesia

2020

Spontaneous electroencephalogram (EEG) and auditory evoked potentials (AEP) have been suggested to monitor the level of consciousness during anesthesia. As both signals reflect different neuronal pathways, a combination of parameters from both signals may provide broader information about the brain status during anesthesia. Appropriate parameter selection and combination to a single index is crucial to take advantage of this potential. The field of machine learning offers algorithms for both parameter selection and combination. In this study, several established machine learning approaches including a method for the selection of suitable signal parameters and classification algorithms are a…

Subcellular localization and characterization of nitric oxide synthase(s) in endothelial cells: physiological implications.

1994

Endothelial cells (EC) contain a constitutive Ca2+/calmodulin-dependent nitric oxide (NO) synthase (cNOS) which plays an important role in the local control of vascular tone. We compared the subcellular distribution of this enzyme in cultured and freshly isolated pig EC by determination of specific cNOS activity and immunoblot analysis. Similar studies were also performed with cultured and freshly isolated bovine and cultured human EC. Enzyme activity was predominantly (&amp;gt; 70%) associated with the particulate fraction of all EC types tested and was highest in freshly isolated porcine EC. Both specific cNOS activity and immunoreactivity were substantially higher (&amp;gt; 3-fold) in th…