Measuring levels of proteins by various technologies: can we learn more by measuring turnover?

Rapid screening and in vivo target occupancy quantitative evaluation of xanthine oxidase inhibitors based on drug-target binding kinetics research strategy: A case study of Chrysanthemum morifolium Ramat

Chrysanthemum morifolium Ramat. is a kind of food and drug dual-use traditional Chinese medicine possessing multiple pharmacological and biochemical benefits. In our study, a rapid and high-throughput method based on Surface plasmon resonance (SPR) biosensor technology was developed and verified for screening potential xanthine oxidase (XOD) inhibitors exemplarily in the Chrysanthemum morifolium Ramat. Coupled with ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS), 14 XOD-binders were identified. In the SPR-based biosensor and molecular docking analysis, most compounds exhibited a strong affinity and binding kinetic property (association rate constant, K_on and dissociation rate constant, K_off) for XOD and could be regarded as potential inhibitors. More importantly, to further accurately assess target occupancy of candidate compounds in vivo, a mathematical model was established and verified involving three crucial intrinsic kinetic processes (Pharmacokinetics, Binding kinetic and Target kinetic). Overall, the proposed screening and assessment strategy could be proved an effective theoretical basis for further pharmacodynamic evaluation.

Computational Analysis of Altering Cell Fate

The notion of reprogramming cell fate is a direct challenge to the traditional view in developmental biology that a cell's phenotypic identity is sealed after undergoing differentiation. Direct experimental evidence, beginning with the somatic cell nuclear transfer experiments of the twentieth century and culminating in the more recent breakthroughs in transdifferentiation and induced pluripotent stem cell (iPSC) reprogramming, have rewritten the rules for what is possible with cell fate transformation. Research is ongoing in the manipulation of cell fate for basic research in disease modeling, drug discovery, and clinical therapeutics. In many of these cell fate reprogramming experiments, there is often little known about the genetic and molecular changes accompanying the reprogramming process. However, gene regulatory networks (GRNs) can in some cases be implicated in the switching of phenotypes, providing a starting point for understanding the dynamic changes that accompany a given cell fate reprogramming process. In this chapter, we present a framework for computationally analyzing cell fate changes by mathematically modeling these GRNs. We provide a user guide with several tutorials of a set of techniques from dynamical systems theory that can be used to probe the intrinsic properties of GRNs as well as study their responses to external perturbations.

Effect of a change in housing conditions on body weight, behavior and brain neurotransmitters in male C57BL/6J mice

The development of modern housing regimes such as individually ventilated cage (IVC) systems has become very popular and attractive in order to reduce spreading of pathogenic organisms and to lower the risk to develop a laboratory animal allergy for staff members. Additionally, optimal housing of laboratory animals contributes to improve animal health status and ensures high and comparable experimental and animal welfare standards. However, it has not been clearly elucidated whether 1) a change to IVC systems have an impact on various physiological phenotypic parameters of mice when compared to conventional, standard cages and 2) if this is further affected by changing from social to single housing. Therefore, we investigated the influence of a change in housing conditions (standard cages with social housing changed to standard or IVC cages combined with social or single housing) on body weight, behavior and a neurochemical fingerprint of male C57BL/6J mice. Body weight progression was significantly reduced when changing mice to single or social IVC cages as well as in single standard cages when compared to social standard housing. Automated motor activity measurement in the open field showed that mice maintained in social husbandry with standard cages displayed the lowest exploratory behavior but the highest activity difference upon amphetamine treatment. Elevated plus maze test revealed that a change to IVC single and social housing as well as single standard housing produced anxiety-related behavior when compared to maintenance in social standard housing. Additionally, postmortem neurochemical analysis of the striatum using high-performance liquid chromatography coupled to electrochemical detection showed significant differences in striatal dopamine and serotonin turnover levels. In summary, our data indicate a crucial influence of a change in housing conditions on several mouse phenotype parameters. We propose that the maintenance of well-defined housing conditions is mandatory to ensure reproducible and comparable results and contributes to the application of the 3R refinement principle in animal studies by contributing to welfare and hygienical standards.

CART Peptides and Drugs of Abuse: A Review of Recent Progress

Earlier studies suggesting an involvement of cocaine and amphetamine regulated transcript peptide (CARTp) in the actions of drugs of abuse are confirmed in the most recent publications. This seems especially true for the psychostimulants where CARTp in the nucleus accumbens inhibits or regulates the actions of these drugs; the regulation is lost after repeated drug use which may be an important mechanism in addiction. The other drugs, including nicotine, alcohol, opiates, and perhaps caffeine can affect CARTp or CART mRNA levels. While the exact mechanism is not always clear, the hope is that these findings may provide some insight for the development of medications. While binding studies indicate the existence of specific G-protein coupled receptors (GPCR) receptors for CARTp, major work to be done is the cloning of these receptors.