Laser speckle imaging (LSI), a new technique that measures an index of plaque viscoelasticity, has been investigated recently to characterize atherosclerotic plaques. These prior studies demonstrated the diagnostic potential of LSI for detecting high-risk plaques and were conducted ex vivo. To conduct intracoronary LSI in vivo, the laser speckle pattern must be transmitted from the coronary wall to the image detector in the presence of cardiac motion. Small-diameter, flexible optical fiber bundles, similar to those used in coronary angioscopy, may be incorporated into an intravascular catheter for this purpose. A key challenge is that laser speckle is influenced by inter-fiber leakage of light, which may be exacerbated during bundle motion. In this study, we tested the capability of optical fiber bundles to transmit laser speckle patterns obtained from atherosclerotic plaques and evaluated the influence of motion on the diagnostic accuracy of fiber bundle-based LSI. Time-varying heliumneon laser speckle images of aortic plaques were obtained while cyclically moving the flexible length of the bundle to mimic coronary motion. Our results show that leached fiber bundles may reliably transmit laser speckle images in the presence of cardiac motion, providing a viable option to conduct intracoronary LSI.
Summary Background Growth rate is determined not only by extracellular cues such as nutrient availability but also by intracellular processes. Changes in cell morphology in budding yeast, mediated by polarization of the actin cytoskeleton, have been shown to reduce cell growth. Results Here we demonstrate that polarization of the actin cytoskeleton inhibits the highly conserved Target of Rapamycin Complex 1 (TORC1) pathway. This downregulation is suppressed by inactivation of the TORC1 pathway regulatory Iml1 complex, which also regulates TORC1 during nitrogen starvation. We further demonstrate that attenuation of growth is important for cell recovery after conditions of prolonged polarized growth. Conclusions Our results indicate that extended periods of polarized growth inhibit protein synthesis, mass accumulation, and the increase in cell size at least in part through inhibiting the TORC1 pathway. We speculate that this mechanism serves to coordinate the ability of cells to increase in size with their biosynthetic capacity.
We demonstrate a method to enhance the time resolution of a commercial Coulter counter and enable continuous and long-term cell size measurements for growth rate analyses essential to understanding basic cellular processes, such as cell size regulation and cell cycle progression. Our simple modifications to a commercial Coulter counter create controllable cell culture conditions within the sample compartment and combine temperature control with necessary adaptations to achieve measurement stability over several hours. We also wrote custom software, detailed here, to analyze instrument data files collected by either this continuous method or standard, periodic sampling. We use the continuous method to measure the growth rate of yeast in G1 during a prolonged arrest and, in different samples, the dependency of growth rate on cell size and cell cycle position in arrested and proliferating cells. We also quantify with high time resolution the response of mouse lymphoblast cell culture to drug treatment. This method provides a technique for continuous measurement of cell size that is applicable to a large variety of cell types and greatly expands the set of analysis tools available for the Coulter counter.
Introduction: The Ion Torrent Genexus System has redefined the genomic profiling paradigm as the first fully-integrated, next-generation sequencing (NGS) research platform to provide an automated sample-to-report workflow with results in a single day. With a purification instrument, an enhanced chip architecture, and downstream reporting, the Genexus System provides a convenient solution to enable oncology research. Here we highlight the oncology research applications and high-throughput NGS capabilities of the Genexus System with Oncomine Comprehensive Assay Plus (OCA Plus), an oncology research panel that can detect variants, fusions, and evaluate key oncology research endpoints. We demonstrate the ability of OCA Plus on Genexus to evaluate tumor mutational burden (TMB), microsatellite instability (MSI), loss of heterozygosity (LOH), and homologous recombination repair deficiency (HRD). Methods: The high-throughput capabilities of the Genexus System enable it to support large oncology research panels such as OCA Plus, which comprises over 13,000 amplicons. The extensive per sample coverage allows for comprehensive DNA and RNA genomic profiling of relevant cancer biomarkers in over 500 genes including detection of over 1,300 fusion isoforms. We utilized high-molecular weight and FFPE samples, reference controls, and orthogonally tested research samples to evaluate DNA variant calling, RNA fusion calling, and key oncology research endpoints, including MSI, LOH, TMB, and HRD. Results: Commercially sourced reference control and research samples were sequenced using OCA Plus on the Genexus System. Sequencing data metrics showed ≥24 million reads per sample, with four samples supported per run. The high-throughput capacity of the Genexus chip architecture results in >95% of amplicons achieving a minimum of 500X coverage with an average coverage uniformity of ≥95% when evaluated across all >13,000 amplicons. Variant calling was assessed using the AcroMetrix Oncology Hotspot Control which has 328 hotspot variants covered by OCA Plus. Variant calling performance showed a hotspot and de novo variant sensitivity and PPV >95%. MSI score and status were assessed using known MSI-High and microsatellite stable (MSS) research samples and FFPE samples of interest. Results show high concordance with data from OCA Plus on GeneStudio. Conclusions: The increased throughput of the Genexus System combined with minimal touchpoints and a rapid turnaround time enables comprehensive genomic profiling for research assays such as OCA Plus where an increased number of sequencing reads leads to greater sensitivity for detecting rare variants and low-level fusion transcripts. Further, accurate characterization of key oncology research endpoints, such as TMB, MSI, LOH, and HRD, allow the Genexus System to accelerate research in the field of oncology. Citation Format: Kayla Zochowski, Dinesh Cyanam, Geoffrey Lowman, Jennifer Kilzer, Sameh El-Difrawy, Yan Zhu, Tanaya Puranik, Alex Phan, Derek Wong, Edith Kwong, Coleen Nemes, Iris Casuga, Frances Chan, Eun Ji Kim, Jianjun Guo, Vinay Mittal, Emily Norris, Shrutii Sarda, Mohit Gupta, Fan Shen, Steven Roman, Gabriel Vargas, Ying Jin, Annie Kraltcheva, Paul Williams, Amneet Gulati, Justin Rigby, Christopher Hoff, Richard Meade, Elaine Wong-Ho, Andrew Wong, Jamsheed Ghadiri, David Garcia-Viramontes, Scott Myrand, Seth Sadis. High-throughput next-generation sequencing research solutions for detection of oncology variants, gene fusion events, and key oncology endpoints [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 42.
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