Living in a noisy world-origins of gene expression noise and its impact on cellular decision-making.

The expression level of a gene can vary between genetically identical cells under the same environmental condition-a phenomenon referred to as gene expression noise. Several studies have now elucidated a central role of transcription factors in the generation of expression noise. Transcription factors, as the key components of gene regulatory networks, drive many important cellular decisions in response to cellular and environmental signals. Therefore, a very relevant question is how expression noise impacts gene regulation and influences cellular decision-making. In this Review, we summarize the current understanding of the molecular origins of expression noise, highlighting the role of transcription factors in this process, and discuss the ways in which noise can influence cellular decision-making. As advances in single-cell technologies open new avenues for studying expression noise as well as gene regulatory circuits, a better understanding of the influence of noise on cellular decisions will have important implications for many biological processes.

Transcription factor binding process is the primary driver of noise in gene expression.

Noise in expression of individual genes gives rise to variations in activity of cellular pathways and generates heterogeneity in cellular phenotypes. Phenotypic heterogeneity has important implications for antibiotic persistence, mutation penetrance, cancer growth and therapy resistance. Specific molecular features such as the presence of the TATA box sequence and the promoter nucleosome occupancy have been associated with noise. However, the relative importance of these features in noise regulation is unclear and how well these features can predict noise has not yet been assessed. Here through an integrated statistical model of gene expression noise in yeast we found that the number of regulating transcription factors (TFs) of a gene was a key predictor of noise, whereas presence of the TATA box and the promoter nucleosome occupancy had poor predictive power. With an increase in the number of regulatory TFs, there was a rise in the number of cooperatively binding TFs. In addition, an increased number of regulatory TFs meant more overlaps in TF binding sites, resulting in competition between TFs for binding to the same region of the promoter. Through modeling of TF binding to promoter and application of stochastic simulations, we demonstrated that competition and cooperation among TFs could increase noise. Thus, our work uncovers a process of noise regulation that arises out of the dynamics of gene regulation and is not dependent on any specific transcription factor or specific promoter sequence.

Oxygenation therapies for improved wound healing: current trends and technologies.

Degree of oxygenation is one of the important parameters governing various processes, including cell proliferation, angiogenesis, extracellular matrix production, and even combating the microbial burden at the wound site, all of which are essential for tissue function restoration and integrity. Inadequate oxygenation interrupts the normal healing process and delays patient recovery. The present article overviews the role of oxygen in the wound healing process and different oxygenation therapies that have been applied for healing dermal wounds. Furthermore, we critically assessed various challenges and opportunities in the near future for adequate and controlled oxygen delivery at the wounded site with minimal toxicity.

Real-world weight change, adherence, and discontinuation among patients with type 2 diabetes initiating glucagon-like peptide-1 receptor agonists in the UK.

INTRODUCTION: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a type 2 diabetes mellitus (T2DM) treatment with demonstrated weight loss benefits in clinical trials. However, the extent to which real-world patients with T2DM achieve clinically meaningful weight loss (≥5%) has not been well characterized. Analysis of real-world data suggests adherence to injectable GLP-1 RAs is suboptimal and discontinuation following the first year of therapy is poorly characterized. RESEARCH DESIGN AND METHODS: A retrospective cohort study among patients with T2DM initiating injectable GLP-1 RA therapy was conducted using the Clinical Practice Research Datalink that includes primary care medical records for 13 million patients in the UK. This study assessed weight change, adherence (proportion of days covered (PDC) ≥80%), and discontinuation (≥90-day gap between prescriptions) at 12 and 24 months during the study period spanning January 2009-December 2017. RESULTS: Among 589 patients initiating a GLP-1 RA, 56.4% were female and the median age was 54 years (IQR (46, 61)). The median body mass index was 41.2 kg/m2 (IQR (35.8, 46.4)). Among patients with weight measures available (n=341 at 12 months; n=232 at 24 months), 33.4% and 43.5% achieved weight loss ≥5% of baseline weight at 12 and 24 months, respectively. At 12 and 24 months, 64.5% and 59.2% were adherent, and 45.2% and 64.7% discontinued, respectively. CONCLUSIONS: A minority of patients initiating GLP-1 RAs achieved ≥5% weight loss, suggesting the real-world benefit of these agents on weight loss may be lower than that observed in clinical trials. Patients on GLP-1 RAs may benefit from additional support to improve long-term adherence.

Real-World Adherence and Discontinuation of Glucagon-Like Peptide-1 Receptor Agonists Therapy in Type 2 Diabetes Mellitus Patients in the United States.

AIM: To assess adherence and discontinuation of injectable glucagon-like peptide-1 receptor agonists (GLP-1 RA) at 12 and 24 months among adult type 2 diabetes mellitus (T2DM) patients in the United States initiating GLP-1 RA using the administrative claims-based database, Optum Clinformatics® Data Mart 7.1. METHODS: A retrospective study was conducted from 01/2009 to 12/2017. Patients were required to be continuously enrolled for 12 months prior to their first GLP-1 RA prescription. Proportion of days covered (PDC) from prescription claims ≥0.80 defined adherence. Discontinuation was defined as a ≥90-day gap from the last date of GLP-1 RA supply to the first date of subsequent prescription claim. RESULTS: A total of 4791 T2DM patients had ≥1 and 3907 had ≥2 GLP-1 RA prescription claims. 50.9% and 47.4% of patients were adherent at 12 and 24 months, respectively. Adherence was significantly higher among patients on weekly vs daily doses (p<0.001). Median time to discontinuation was 13 months. The discontinuation rate was 47.7% and 70.1% at 12 and 24 months, respectively, with differences at 24 months for age and dosing frequency (p<0.001 for both). CONCLUSION: Over half of T2DM patients initiating GLP-1 RA were non-adherent and the majority (70.1%) discontinued therapy by 24 months. Reasons for non-adherence and discontinuation merit further research.

Inexpensive and Versatile Paper-Based Platform for 3D Culture of Liver Cells and Related Bioassays.

The present study delineates the fabrication of paper-based devices for culturing liver cells and developing related bioassays. The devices were prepared by conventional lab-based LaserJet printing technology and employed for 3D cell culture. Our results demonstrated that the devices efficiently supported the growth of multiple cell types incuding HepG2, HUVEC, fibroblasts, and MSCs. We further showed that the device specifications (grade of paper or design parameters) greatly impacted the functional phenotype of the HepG2 cells. We also explored the application of the developed devices for routine cell culture, drug screening, coculture, and transwell migration assays. The cellular responses observed on the paper under different culture configurations were similar to those obtained in the case of tissue culture plate (TCP). Moreover, we showed that the paper-based devices were compatible with the immunocytochemistry and ELISA procedures (no indication of nonspecific matrix-antibody interaction). Considering the simplicity, experimental flexibility, cost-effectiveness, and multiplexibility of the paper-based liver models, it is deemed to be ideal for developing cell-based bioassays, especially in resource-limited settings.