Differential effect of regadenoson versus dipyridamole on heart rate in patients with left bundle branch block: How does it affect the results of pharmacological nuclear stress testing?

Background: Myocardial perfusion imaging (MPI) stress test is performed either using exercise as a stress modality or through the use of pharmacological vasodilator agents in those who cannot exercise. Regadenoson and dipyridamole are some of the most common vasodilator agents used. We aim to study the effect of these agents on the heart rate and the imaging results.

Imaging Reporters for Proteasome Activity Identify Tumor- and Metastasis-Initiating Cells.

Tumor-initiating cells, also designated as cancer stem cells, are proposed to constitute a subpopulation of malignant cells central to tumorigenesis, metastasis, and treatment resistance. We analyzed the activity of the proteasome, the primary organelle for targeted protein degradation, as a marker of tumor- and metastasis-initiating cells. Using human and mouse breast cancer cells expressing a validated fluorescent reporter, we found a small subpopulation of cells with low proteasome activity that divided asymmetrically to produce daughter cells with low or high proteasome activity.

Macroscopic stiffness of breast tumors predicts metastasis.

Mechanical properties of tumors differ substantially from normal cells and tissues. Changes in stiffness or elasticity regulate pro-metastatic behaviors of cancer cells, but effects have been documented predominantly in isolated cells or in vitro cell culture systems. To directly link relative stiffness of tumors to cancer progression, we combined a mouse model of metastatic breast cancer with ex vivo measurements of bulk moduli of freshly excised, intact tumors.