Water, urea, sodium, chloride, and potassium transport in the in vitro isolated perfused papillary collecting duct

The collecting ducts are formed in the renal cortex by the connection of several nephrons. They descend within the medullary rays of the cortex, penetrate the outer medulla, and in the inner medulla successively fuse together. Based on these topographical considerations, we can recognize three segments of the collecting duct system: the cortical collecting tubule, the outer medullary collecting duct, and the papillary collecting duct. In this review, we call papillary collecting duct (PCD) that part of the collecting duct system that extends from the junction of outer medulla and inner medulla to the area cribosa. The collecting ducts in the outer medullary zone rarely have branches; however, such branches present in the inner zone have hampered study by micropuncture and microcatheterization techniques. The cortical collecting tubule (CCT) contains two types of cells, principal and intercalated cells, whereas in most animals the PCD contains only principal cells [1]. The general ultrastructure of the PCD cell seems simpler than that of the cortical collecting tubule, suggesting that the PCD is less specialized and less metabolically active than other nephron segments [2]. However, the accumulated data reveal a remarkable reabsorptive capacity for water and sodium by the PCD [3–6], thus indicating that this final part of the nephron plays an important role in the regulation of salt and water balance

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Polymer-Based Photocatalytic Hydrogen Generation

The study of the complex interfaces between organic semiconductors and liquids have recently gained increasing attention due to their interesting applications as biosensors in biological environments, in photovoltaics, and in bioinspired light-harvesting systems. Here, we report a detailed characterization of the interface between polymer films and electrolytic solutions, both by photocurrent spectroscopy and electrochemical measurements. In particular, we demonstrate that a photocatalytic semi-water splitting reaction, leading to hydrogen evolution, occurs at the polymer surface, directly contacted to an aqueous saline (NaCl) solution, as a consequence of visible-light generated photocurrent. We propose here a fully unexplored application of organic systems, i.e. the development of fuel cells: our results pave the way to the exploitation of organic polymers, seawater and solar energy as the sole raw materials for completely clean, sustainable, and economical hydrogen production