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Angiogenesis Aug 2018The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as... (Review)
Review
The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.
Topics: Animals; Biological Assay; Guidelines as Topic; Humans; Mice; Neoplasms; Neovascularization, Pathologic
PubMed: 29766399
DOI: 10.1007/s10456-018-9613-x -
Current Protocols in Protein Science Feb 2015Purification of recombinant proteins for biochemical assays and structural studies is time-consuming and presents inherent difficulties that depend on the optimization...
Purification of recombinant proteins for biochemical assays and structural studies is time-consuming and presents inherent difficulties that depend on the optimization of protein stability. The use of dyes to monitor thermal denaturation of proteins with sensitive fluorescence detection enables rapid and inexpensive determination of protein stability using real-time PCR instruments. By screening a wide range of solution conditions and additives in a 96-well format, the thermal shift assay easily identifies conditions that significantly enhance the stability of recombinant proteins. The same approach can be used as an initial low-cost screen to discover new protein-ligand interactions by capitalizing on increases in protein stability that typically occur upon ligand binding. This unit presents a methodological workflow for small-scale, high-throughput thermal denaturation of recombinant proteins in the presence of SYPRO Orange dye.
Topics: Biological Assay; Fluorometry; Ligands; Protein Stability; Proteins; Temperature
PubMed: 25640896
DOI: 10.1002/0471140864.ps2809s79 -
Journal of Visualized Experiments : JoVE Aug 2018Cell migration is an important process that influences many aspects of health, such as wound healing and cancer, and it is, therefore, crucial for developing methods to...
Cell migration is an important process that influences many aspects of health, such as wound healing and cancer, and it is, therefore, crucial for developing methods to study the migration. The scratch assay has long been the most common in vitro method to test compounds with anti- and pro-migration properties because of its low cost and simple procedure. However, an often-reported problem of the assay is the accumulation of cells across the edge of the scratch. Furthermore, to obtain data from the assay, images of different exposures must be taken over a period of time at the exact same spot to compare the movements of the migration. Different analysis programs can be used to describe the scratch closure, but they are labor intensive, inaccurate, and forces cycles of temperature changes. In this study, we demonstrate an optimized method for testing the migration effect, e.g. with the naturally occurring proteins Human- and Bovine-Lactoferrin and their N-terminal peptide Lactoferricin on the epithelial cell line HaCaT. A crucial optimization is to wash and scratch in PBS, which eliminates the aforementioned accumulation of cells along the edge. This could be explained by the removal of cations, which have been shown to have an effect on keratinocyte cell-cell connection. To ensure true detection of migration, pre-treating with mitomycin C, a DNA synthesis inhibitor, was added to the protocol. Finally, we demonstrate the automated optical camera, which eliminates excessive temperature cycles, manual labor with scratch closure analysis, while improving on reproducibility and ensuring analysis of identical sections of the scratch over time.
Topics: Biological Assay; Cell Line; Cell Movement; Gamma Cameras; Humans; In Vitro Techniques; Reproducibility of Results
PubMed: 30148500
DOI: 10.3791/57691 -
SLAS Discovery : Advancing Life... Jun 2019Many factors must be considered during the optimization of an enzyme assay. These include the choice of buffer and its composition, the type of enzyme and its...
Many factors must be considered during the optimization of an enzyme assay. These include the choice of buffer and its composition, the type of enzyme and its concentration, as well as the type of substrate and concentrations, the reaction conditions, and the appropriate assay technology. The process of an enzyme assay optimization, in our experience, can take more than 12 weeks using the traditional one-factor-at-a-time approach. In contrast, the design of experiments (DoE) approaches have the potential to speed up the assay optimization process and provide a more detailed evaluation of tested variables. However, not all researchers are aware of DoE approaches or believe that it is easy to employ a DoE approach for the optimization of an assay. In order to facilitate enzyme assay developers to use DoE methodologies, we present in detail the steps required to identify in less than 3 days (1) the factors that significantly affect the activity of an enzyme and (2) the optimal assay conditions using a fractional factorial approach and response surface methodology. This is exemplified with the optimization of assay conditions for the human rhinovirus-3C protease, and the methodology used could be employed as a basic guide for the speedy identification of the optimum assay conditions for any enzyme.
Topics: 3C Viral Proteases; Biological Assay; Cysteine Endopeptidases; Enzyme Assays; Humans; Research Design; Substrate Specificity; Viral Proteins
PubMed: 30802413
DOI: 10.1177/2472555219830084 -
Journal of Visualized Experiments : JoVE Mar 2018The aim of this work is to show a novel method to evaluate the ability of some immunomodulatory molecules, such as antimicrobial peptides (AMPs), to stimulate cell...
The aim of this work is to show a novel method to evaluate the ability of some immunomodulatory molecules, such as antimicrobial peptides (AMPs), to stimulate cell migration. Importantly, cell migration is a rate-limiting event during the wound-healing process to re-establish the integrity and normal function of tissue layers after injury. The advantage of this method over the classical assay, which is based on a manually made scratch in a cell monolayer, is the usage of special silicone culture inserts providing two compartments to create a cell-free pseudo-wound field with a well-defined width (500 μm). In addition, due to an automated image analysis platform, it is possible to rapidly obtain quantitative data on the speed of wound closure and cell migration. More precisely, the effect of two frog-skin AMPs on the migration of bronchial epithelial cells will be shown. Furthermore, pretreatment of these cells with specific inhibitors will provide information on the molecular mechanisms underlying such events.
Topics: Animals; Biological Assay; Cell Movement; Humans; Wound Healing
PubMed: 29608162
DOI: 10.3791/56825 -
Natural Product Reports Jul 2020Covering: up to 2020The National Cancer Institute of the United States (NCI) has initiated a Cancer Moonshot program entitled the NCI Program for Natural Product... (Review)
Review
Covering: up to 2020The National Cancer Institute of the United States (NCI) has initiated a Cancer Moonshot program entitled the NCI Program for Natural Product Discovery. As part of this effort, the NCI is producing a library of 1 000 000 partially purified natural product fractions which are being plated into 384-well plates and provided to the research community free of charge. As the first 326 000 of these fractions have now been made available, this review seeks to describe the general methods used to collect organisms, extract those organisms, and create a prefractionated library. Importantly, this review also details both cell-based and cell-free bioassay methods and the adaptations necessary to those methods to productively screen natural product libraries. Finally, this review briefly describes post-screen dereplication and compound purification and scale up procedures which can efficiently identify active compounds and produce sufficient quantities of natural products for further pre-clinical development.
Topics: Biological Assay; Biological Products; Drug Discovery; High-Throughput Screening Assays; Humans; Small Molecule Libraries
PubMed: 32186299
DOI: 10.1039/c9np00068b -
Basic & Clinical Pharmacology &... May 2021Predictive biomarkers play an important role in our efforts to individualize pharmacotherapy, and within recent years, a number of different types of assays have been... (Review)
Review
Predictive biomarkers play an important role in our efforts to individualize pharmacotherapy, and within recent years, a number of different types of assays have been introduced. These biomarkers may potentially support the selection and dosage of specific drugs in order to maximize efficacy and minimize adverse reactions in the individual patient. However, in many instances, the scientific and clinical evidence is insufficient to support the prescribing decision. When predictive biomarkers are used to guide pharmacotherapy, it is important to secure that decisions are based on solid clinical evidence. Here, the regulatory authorities, especially the FDA, have been at the forefront in relation to regulate this type of biomarker assay in order to secure patient safety. The approval process for companion diagnostics is an example of this effort, where the scientific validity of the biomarker and assay is in focus. With the approaching implementation of the new IVD Regulation, greater attention will also be paid to analytical and clinical validity of biomarker assays in the EU. For any type of predictive biomarker assay, including pharmacogenetic and tumour profiling tests, the clinical evidence needs to be in place before they are used routinely in the clinic.
Topics: Biological Assay; Biomarkers; Diagnostic Test Approval; European Union; Pharmacogenomic Testing; Precision Medicine; Reagent Kits, Diagnostic; United States; United States Food and Drug Administration
PubMed: 33665955
DOI: 10.1111/bcpt.13578 -
Cold Spring Harbor Perspectives in... Aug 2017The experimental study of prions requires a model for their propagation. However, because prions lack nucleic acids, the simple techniques used to replicate bacteria and... (Review)
Review
The experimental study of prions requires a model for their propagation. However, because prions lack nucleic acids, the simple techniques used to replicate bacteria and viruses are not applicable. For much of the history of prion research, time-consuming bioassays in animals were the only option for measuring infectivity. Although cell models and other in vitro tools for the propagation of prions have been developed, they all suffer limitations, and animal bioassays remain the gold standard for measuring infectivity. A wealth of recent data argues that both β-amyloid (Aβ) and tau proteins form prions that cause Alzheimer's disease, and α-synuclein forms prions that cause multiple system atrophy and Parkinson's disease. Cell and animal models that recapitulate some of the key features of cell-to-cell spreading and distinct strains of prions can now be measured.
Topics: Animals; Biological Assay; Humans; Prions
PubMed: 28246183
DOI: 10.1101/cshperspect.a023499 -
International Journal of Molecular... May 2021Antibody therapeutics are expanding with promising clinical outcomes, and diverse formats of antibodies are further developed and available for patients of the most... (Review)
Review
Antibody therapeutics are expanding with promising clinical outcomes, and diverse formats of antibodies are further developed and available for patients of the most challenging disease areas. Bispecific antibodies (BsAbs) have several significant advantages over monospecific antibodies by engaging two antigen targets. Due to the complicated mechanism of action, diverse structural variations, and dual-target binding, developing bioassays and other types of assays to characterize BsAbs is challenging. Developing bioassays for BsAbs requires a good understanding of the mechanism of action of the molecule, principles and applications of different bioanalytical methods, and phase-appropriate considerations per regulatory guidelines. Here, we review recent advances and case studies to provide strategies and insights for bioassay development for different types of bispecific molecules.
Topics: Animals; Antibodies, Bispecific; Antigens; Biological Assay; Humans; Immunotherapy
PubMed: 34069573
DOI: 10.3390/ijms22105350 -
Sensors (Basel, Switzerland) Dec 2020Fluorescence polarization holds considerable promise for bioanalytical systems because it allows the detection of selective interactions in real time and a choice of... (Review)
Review
Fluorescence polarization holds considerable promise for bioanalytical systems because it allows the detection of selective interactions in real time and a choice of fluorophores, the detection of which the biosample matrix does not influence; thus, their choice simplifies and accelerates the preparation of samples. For decades, these possibilities were successfully applied in fluorescence polarization immunoassays based on differences in the polarization of fluorophore emissions excited by plane-polarized light, whether in a free state or as part of an immune complex. However, the results of recent studies demonstrate the efficacy of fluorescence polarization as a detected signal in many bioanalytical methods. This review summarizes and comparatively characterizes these developments. It considers the integration of fluorescence polarization with the use of alternative receptor molecules and various fluorophores; different schemes for the formation of detectable complexes and the amplification of the signals generated by them. New techniques for the detection of metal ions, nucleic acids, and enzymatic reactions based on fluorescence polarization are also considered.
Topics: Biological Assay; Fluorescence Polarization; Fluorescent Dyes; Metals; Nucleic Acids
PubMed: 33322750
DOI: 10.3390/s20247132