Quantitative determination of urea concentrations in cell culture medium

Zawada, Robert J.X.; Kwan, Peggy KwanP.; Olszewski, Kellen L.; Llinas, Manuel LlinasM.; S, Huang

doi:10.1139/o09-011

Cited by 55 publications

(37 citation statements)

References 10 publications

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“…Urea secretion was measured using the urease based colorimetric method described in Zawada et al [17]. Glucose concentration in 10 μL samples was determined by the Yellow Springs Glucose 2300 STAT as per manufacturer’s instructions.…”

Section: Methodsmentioning

confidence: 99%

On the adhesion-cohesion balance and oxygen consumption characteristics of liver organoids

et al. 2017

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Liver organoids (LOs) are of interest in tissue replacement, hepatotoxicity and pathophysiological studies. However, it is still unclear what triggers LO self-assembly and what the optimal environment is for their culture. Hypothesizing that LO formation occurs as a result of a fine balance between cell-substrate adhesion and cell-cell cohesion, we used 3 cell types (hepatocytes, liver sinusoidal endothelial cells and mesenchymal stem cells) to investigate LO self-assembly on different substrates keeping the culture parameters (e.g. culture media, cell types/number) and substrate stiffness constant. As cellular spheroids may suffer from oxygen depletion in the core, we also sought to identify the optimal culture conditions for LOs in order to guarantee an adequate supply of oxygen during proliferation and differentiation. The oxygen consumption characteristics of LOs were measured using an O2 sensor and used to model the O2 concentration gradient in the organoids. We show that no LO formation occurs on highly adhesive hepatic extra-cellular matrix-based substrates, suggesting that cellular aggregation requires an optimal trade-off between the adhesiveness of a substrate and the cohesive forces between cells and that this balance is modulated by substrate mechanics. Thus, in addition to substrate stiffness, physicochemical properties, which are also critical for cell adhesion, play a role in LO self-assembly.

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Section: Methodsmentioning

confidence: 99%

On the adhesion-cohesion balance and oxygen consumption characteristics of liver organoids

et al. 2017

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“…The reaction causes a color change, the intensity of which can be measured using a spectrophotometer. Urea assay reagents in this test were prepared based on the work of Jung et al [19] and Zawada et al [20]. After mass transfer tests, assaying was conducted by first mixing each of the reagents directly in a microwell-plate.…”

Section: Methodsmentioning

confidence: 99%

Self-registration methods for increasing membrane utilization within compression-sealed microchannel hemodialysers

Paul

Porter

2014

Journal of Manufacturing Processes

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More than 1.2 million people worldwide require regular hemodialysis therapy to treat end stage renal failure. Current hemodialysis systems are too expensive to support at-home hemodialysis where more frequent and longer duration treatment can lead to better patient outcomes. The key cost driver for hemodialysers is the cost of the hemodialysis membrane. Microchannel hemodialysers are smaller providing the potential to use significantly less membrane. Prior work has demonstrated the use of sealing bosses to form compression seals in microchannel hemodialysers. In this paper, estimates show that the percentage of the membrane utilized for mass transfer is highly dependent on the design and registration accuracy of adjacent blood and dialysate laminae. Efforts here focus on the development of a self-registration method to align polycarbonate laminae compatible with compression sealing schemes for membrane separation applications. Self-nesting registration methods were demonstrated with average registration accuracies of 11.4 ± 7.2 μm measured over a 50 mm scale. Analysis shows that the registration accuracy is constrained by tolerances in the embossing process. A dialysis test article was produced using the self-nesting registration method showing a measured average one-dimensional misregistration of 18.5 μm allowing a potential 41.4% of the membrane to be utilized for mass transfer when considering both microchannel and header regions. Mass transfer results provide evidence of a twofold to threefold increase in membrane utilization over other designs in the existing literature.

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“…19 It is a colorimetric reaction of urea, o-phthalaldehyde, and N-(1-naphthyl)ethylenediamme (NED). 20 N-(1-naphthyl)ethylenediamme (NED) could be replaced with primaquin 21 in kit urea assay. Prior to the arginase inhibition test of Nor-NOHA as positive control and extracts as samples, optimization of substrate concentration was done with concentration of enzyme 1 U/mL, and some concentration of L-Arginine as substrat.…”

Section: Figure 1: Melastoma Malabathricum Leavesmentioning

confidence: 99%

Inhibitory Effect on Arginase and Total Phenolic Content Determination of Extracts from Different parts of Melastoma malabathricum L.

Sembiring

Elya²,

Sauriasari³

2018

JYP

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The part of the plant were collected and cleaned, dried at room temperature, and then powdered and stored in an air tight glass container. 50 g of each plant part was extracted by maceration with 500 mL of 70% ethanol ABSTRACTBackground: Some phenolic compounds are potential source for arginase inhibitor that can be used in management of disease associated with endothelial dysfunction. Objective: The aim of this study was to investigate the inhibitory effect on arginase and to determine total phenolic content of extracts from different parts of Melastoma malabathricum L. Methods: Each part were extracted with 70% ethanol by maceration. The extracts were mixed with bovine liver arginase and L-arginine as a substrate. The inhibitory effect of extracts were determined in vitro, by measuring its absorbance on 430 nm. Total phenolic content were determined with Folin-Ciocalteu 25% on 750 nm. Results: The 70% ethanol extract of M. malabathricum leaves at 100 µg/mL was found to have highest inhibition (81.26 ± 5.27 %) followed by flower 73.39 ± 9.39%, fruit 67.63 ± 7.61 and stem 61.61 ± 4.56%. The IC 50 value of the most active extract was 62.43 µg/mL while the IC 50 value of N-hidroksi-nor-L-arginin (nor-NOHA) acetate, an arginase inhibitor was found to be 3.91 µg/mL. Total phenolic content of 70% ethanolic extracts of M. malabathricum leaves, flower, fruit and stem was 15.9, 20.7, 6.44, and 6.29%. Conclusion: The 70% ethanol extract of M. malabathricum leaves exhibited the highest inhibition on arginase but highest total phenolic content was from flower part. Pearson correlation test showed no correlation p>0.05 between arginase inhibition and total phenolic content of the samples.

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Quantitative determination of urea concentrations in cell culture medium

Cited by 55 publications

References 10 publications

On the adhesion-cohesion balance and oxygen consumption characteristics of liver organoids

On the adhesion-cohesion balance and oxygen consumption characteristics of liver organoids

Self-registration methods for increasing membrane utilization within compression-sealed microchannel hemodialysers

Inhibitory Effect on Arginase and Total Phenolic Content Determination of Extracts from Different parts of Melastoma malabathricum L.

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