Desensitization of angiotensin receptor function

Desensitization of angiotensin receptor function. Angiotensin II is an eight amino acid peptide which plays a major role in the regulation of cardiovascular homeostasis. The physiologic effects of angiotensin (Ang) II are mediated by a G-protein coupled receptor, termed AT1, which activates phospholipase C. A major factor regulating angiotensin II receptor function is the rapid desensitization following agonist stimulation. However, despite years of investigation, the mechanism by which the angiotensin receptor is regulated remains unclear. The cloning of the AT-1 receptor and the availability of cell lines which stabily express this receptor has helped elucidate these mechanisms. In this paper, we review the data from our laboratory concerning the post-translational regulation of the angiotensin receptor function

Paracrine mechanisms of stem cell reparative and regenerative actions in the heart

Stem cells play an important role in restoring cardiac function in the damaged heart. In order to mediate repair, stem cells need to replace injured tissue by differentiating into specialized cardiac cell lineages and/or manipulating the cell and molecular mechanisms governing repair. Despite early reports describing engraftment and successful regeneration of cardiac tissue in animal models of heart failure, these events appear to be infrequent and yield too few new cardiomyocytes to account for the degree of improved cardiac function observed. Instead, mounting evidence suggests that stem cell mediated repair takes place via the release of paracrine factors into the surrounding tissue that subsequently direct a number of restorative processes including myocardial protection, neovascularization, cardiac remodeling, and differentiation. The potential for diverse stem cell populations to moderate many of the same processes as well as key paracrine factors and molecular pathways involved in stem cell-mediated cardiac repair will be discussed in this review. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited"

901-90 In Vivo Genetic Engineering of Cardiac Cells: Intracoronary Administration of Antisense (AS) Oligonucleotides (ODN)

We have previously documented that transfection of antisense ODN by a highly efficient Sendai virus (HVJ)-liposome delivery system can be utilized to modify lesion formation within the peripheral vasculature in vivo. In this study, we defined the feasibility of modifying cardiac cell gene expression via a catheter-based coronary infusion of AS ODN in rabbits. The coronary artery was cannulated via an over-the-wire approach from the carotid artery. Fluorescein (F)-Iabeled ODN were utilized to evaluate the cellular distribution and kinetics of ODN uptake within the myocardium after a single intraluminal bolus of HVJ-liposomes containing ODN. Cellular uptake of F-ODN was primarily localized in the microvasculature and significant staining was also observed in conduit vessels and cardiac myocytes. Immunohistochemical analysis verified prominent localization of F-ODN within the microvascular endothelium. Expression of F-ODN was observed within 10 minutes, peaked at 1 day, and remained evident for up to one week after transfection by the HVJ-liposome method. In contrast, F-ODN infused within liposomes without the viral particle exhibited transient expression that was undetectable within 3 days. These findings indicate that a single intracoronary bolus infusion of ODN within HVJ-liposomes is a reproducible methodology for delivery of AS ODN to targeted cells within the myocardium. Future studies will characterize the feasibility of using this approach to modify cardiac structure and function via regulating myocardial cell gene expression

Access to lifesaving medical resources for African countries: COVID-19 testing and response, ethics, and politics

Coronavirus disease 2019 (COVID-19) has revealed how strikingly unprepared the world is for a pandemic and how easily viruses spread in our interconnected world. A governance crisis is unfolding alongside the pandemic as health officials around the world compete for access to scarce medical supplies. As governments of African countries, and those in low-income and middle-income countries around the world, seek to avoid potentially catastrophic epidemics and learn from what has worked in other countries, testing and other medical resources are of concern. With accelerating spread, funding is urgently needed. Yet even where there is enough money, many African health authorities are unable to obtain the supplies needed as geopolitically powerful countries mobilise economic, political, and strategic power to procure stocks for their populations. We have seen this before. In the AIDS pandemic lifesaving diagnostics and drugs came to many African countries long after they were available in Europe and North America. In 2020, this situation can be avoided. Although health system weakness remains acute in many places, investments by national governments, the African Union, and international initiatives to tackle AIDS, tuberculosis, malaria, polio, and post-Ebola global health security have built important public health capacities. Global leaders have an ethical obligation to avoid needless loss of life due to the foreseeable prospect of slow and inadequate access to supplies in Africa

A cone-plate apparatus for the in vitro biochemical and molecular analysis of the effect of shear stress on adherent cells

Living cells are constantly exposed to a variety of complex mechanical stimuli which are though to be critical in the control of tissue structure and function. Endothelial and smooth muscle cells in the blood vessel are ideal candidates for the study of blood flow-induced cellular regulation. We describe here a cone-plate viscometer apparatus which is specially-designed for studying the effect of fluid shear stress on large populations of adherent cells in vitro. Using conventional polystyrene tissue culture plates, the apparatus is self-contained, fits inside a standard tissue culture incubator, and provides 75–150 cm 2 of useful surface area for cell growth. This capability makes it ideal for studying gene regulation using Northern analysis, nuclear runoff transcription, transfection with reporter constructs, as well as immunochemical staining. The closed-volume design of the device is also well-suited for isotopic labelling, pharmacological studies, and for the detection of minute amounts of secreted cell products. The setup allows the use of either steady, time- and direction-varying laminar, or turbulent shear stress. We provide a detailed assembly procedure and review the method for computing shear stress magnitude and Reynolds number. Ink flow analysis, dynamic response characterization, and LDH measurements are presented to confirm the device's fluid mechanical properties and demonstrate the absence of cell injury.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43234/1/11022_2004_Article_BF00996123.pd