Point-of-Care Ultrasound Training during Nephrology Fellowship: A National Survey of Fellows and Program Directors.

BACKGROUND AND OBJECTIVES: Point-of-care ultrasound (POCUS)-performed by a clinician during a patient encounter and used in patient assessment and care planning-has many potential applications in nephrology. Yet, US nephrologists have been slow to adopt POCUS, which may affect the training of nephrology fellows. This study sought to identify the current state of POCUS training and implementation in nephrology fellowships. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Concise survey instruments measuring attitudes toward POCUS, its current use, fellow competence, and POCUS curricula were disseminated to (1) 912 US nephrology fellows taking the 2021 Nephrology In-Training Examination and (2) 229 nephrology training program directors and associate program directors. Fisher exact, chi-squared, and Wilcoxon rank sum tests were used to compare the frequencies of responses and the average responses between fellows and training program directors/associate program directors when possible. RESULTS: Fellow and training program directors/associate program directors response rates were 69% and 37%, respectively. Only 38% of fellows (240 respondents) reported receiving POCUS education during their fellowship, and just 33% of those who did receive POCUS training reported feeling competent to use POCUS independently. Similarly, just 23% of training program directors/associate program directors indicated that they had a POCUS curriculum in place, although 74% of training program directors and associate program directors indicated that a program was in development or that there was interest in creating a POCUS curriculum. Most fellow and faculty respondents rated commonly covered POCUS topics-including dialysis access imaging and kidney biopsy-as "important" or "very important," with the greatest interest in diagnostic kidney ultrasound. Guided scanning with an instructor was the highest-rated teaching strategy. The most frequently reported barrier to POCUS program development was the lack of available instructors. CONCLUSIONS: Despite high trainee and faculty interest in POCUS, the majority of current nephrology fellows are not receiving POCUS training. Hands-on training guided by an instructor is highly valued, yet availability of adequately trained instructors remains a barrier to program development. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_09_21_CJN01850222.mp3.

What Are We Doing? A Survey of United States Nephrology Fellowship Program Directors.

Interest in nephrology has been declining in recent years. Long work hours and a poor work/life balance may be partially responsible, and may also affect a fellowship's educational mission. We surveyed nephrology program directors using a web-based survey in order to define current clinical and educational practice patterns and identify areas for improvement. Our survey explored fellowship program demographics, fellows' workload, call structure, and education. Program directors were asked to estimate the average and maximum number of patients on each of their inpatient services, the number of patients seen by fellows in clinic, and to provide details regarding their overnight and weekend call. In addition, we asked about number of and composition of didactic conferences. Sixty-eight out of 148 program directors responded to the survey (46%). The average number of fellows per program was approximately seven. The busiest inpatient services had a mean of 21.5±5.9 patients on average and 33.8±10.7 at their maximum. The second busiest services had an average and maximum of 15.6±6.0 and 24.5±10.8 patients, respectively. Transplant-only services had fewer patients than other service compositions. A minority of services (14.5%) employed physician extenders. Fellows most commonly see patients during a single weekly continuity clinic, with a typical fellow-to-faculty ratio of 2:1. The majority of programs do not alter outpatient responsibilities during inpatient service time. Most programs (approximately 75%) divided overnight and weekend call responsibilities equally between first year and more senior fellows. Educational practices varied widely between programs. Our survey underscores the large variety in workload, practice patterns, and didactics at different institutions and provides a framework to help improve the service/education balance in nephrology fellowships.

A role for the Myoblast city homologues Dock1 and Dock5 and the adaptor proteins Crk and Crk-like in zebrafish myoblast fusion.

Myoblast fusion follows a defined sequence of events that is strikingly similar in vertebrates and invertebrates. Genetic analysis in Drosophila has identified many of the molecules that mediate the different steps in the fusion process; by contrast, the molecular basis of myoblast fusion during vertebrate embryogenesis remains poorly characterised. A key component of the intracellular fusion pathway in Drosophila is the protein encoded by the myoblast city (mbc) gene, a close homologue of the vertebrate protein dedicator of cytokinesis 1 (DOCK1, formerly DOCK180). Using morpholino antisense-oligonucleotide-mediated knockdown of gene activity in the zebrafish embryo, we show that the fusion of embryonic fast-twitch myoblasts requires the activities of Dock1 and the closely related Dock5 protein. In addition, we show that the adaptor proteins Crk and Crk-like (Crkl), with which Dock proteins are known to interact physically, are also required for myoblast fusion.

Regulation of receptor trafficking by GRKs and arrestins.

To ensure that extracellular stimuli are translated into intracellular signals of appropriate magnitude and specificity, most signaling cascades are tightly regulated. One of the major mechanisms involved in the regulation of G protein-coupled receptors (GPCRs) involves their endocytic trafficking. GPCR endocytic trafficking entails the targeting of receptors to discrete endocytic sites at the plasma membrane, followed by receptor internalization and intracellular sorting. This regulates the level of cell surface receptors, the sorting of receptors to degradative or recycling pathways, and in some cases the specific signaling pathways. In this chapter we discuss the mechanisms that regulate receptor endocytic trafficking, emphasizing the role of GPCR kinases (GRKs) and arrestins in this process.

PAR-1 and the microtubule-associated proteins CLASP2 and dynactin-p50 have specific localisation on mouse meiotic and first mitotic spindles.

The site of second meiotic division, marked by the second polar body, is an important reference point in the early mouse embryo. To study its formation, we look at the highly asymmetric meiotic divisions. For extrusion of the small polar bodies during meiosis, the spindles must be located cortically. The positioning of meiotic spindles is known to involve the actin cytoskeleton, but whether microtubules are also involved is not clear. In this study we investigated the patterns of localisation of microtubule regulatory proteins in mouse oocytes. PAR-1 is a member of the PAR (partitioning-defective) family with known roles in regulation of microtubule stability and spindle positioning in other model systems. Here we show its specific localisation on mouse meiotic and first mitotic spindles. In addition, the microtubule-associated proteins CLASP2 (a CLIP associating protein) and dynactin-p50 are found on kinetochores and a subset of microtubule-organising centres. Thus we show specific localisation of microtubule regulatory proteins in mouse oocytes, which could indicate roles in meiotic spindle organisation.

Salicylic acid-induced resistance to Cucumber mosaic virus in squash and Arabidopsis thaliana: contrasting mechanisms of induction and antiviral action.

Salicylic acid (SA)-induced resistance to Cucumber mosaic virus (CMV) in tobacco (Nicotiana tabacum) results from inhibition of systemic virus movement and is induced via a signal transduction pathway that also can be triggered by antimycin A, an inducer of the mitochondrial enzyme alternative oxidase (AOX). In Arabidopsis thaliana, inhibition of CMV systemic movement also is induced by SA and antimycin A. These results indicate that the mechanisms underlying induced resistance to CMV in tobacco and A. thaliana are very similar. In contrast to the situation in tobacco and A. thaliana, in squash (Cucurbita pepo), SA-induced resistance to CMV results from inhibited virus accumulation in directly inoculated tissue, most likely through inhibition of cell-to-cell movement. Furthermore, neither of the AOX inducers antimycin A or KCN induced resistance to CMV in squash. Additionally, AOX inhibitors that compromise SA-induced resistance to CMV in tobacco did not inhibit SA-induced resistance to the virus in squash. The results show that different host species may use significantly different approaches to resist infection by the same virus. These findings also imply that caution is required when attempting to apply findings on plant-virus interactions from model systems to a wider range of host species.

Downregulation of Par3 and aPKC function directs cells towards the ICM in the preimplantation mouse embryo.

Generation of inside cells that develop into inner cell mass (ICM) and outside cells that develop into trophectoderm is central to the development of the early mouse embryo. Critical to this decision is the development of cell polarity and the associated asymmetric (differentiative) divisions of the 8-cell-stage blastomeres. The underlying molecular mechanisms for these events are not understood. As the Par3/aPKC complex has a role in establishing cellular polarity and division orientation in other systems, we explored its potential function in the developing mouse embryo. We show that both Par3 and aPKC adopt a polarized localization from the 8-cell stage onwards and that manipulating their function re-directs cell positioning and consequently influences cell fate. Injection of dsRNA against Par3 or mRNA for a dominant negative form of aPKC into a random blastomere at the 4-cell stage directs progeny of the injected cell into the inside part of the embryo. This appears to result from both an increased frequency by which such cells undertake differentiative divisions and their decreased probability of retaining outside positions. Thus, the natural spatial allocation of blastomere progeny can be over-ridden by downregulation of Par3 or aPKC, leading to a deceased tendency for them to remain outside and so develop into trophectoderm. In addition, this experimental approach illustrates a powerful means of manipulating gene expression in a specific clonal population of cells in the preimplantation embryo.

Activation of multiple antiviral defence mechanisms by salicylic acid.

SUMMARY The plant signal molecule salicylic acid (SA) can induce resistance to a wide range of pathogen types. In the case of viruses, SA can stimulate the inhibition of all three main stages in virus infection: replication, cell-to-cell movement and long-distance movement. Induction of resistance by SA appears to depend, in part, on downstream signalling via the mitochondrion. However, evidence has recently emerged that SA may stimulate a separate downstream pathway, leading to the induction of an additional mechanism of resistance based on RNA interference. In this review our aims are to document these recent advances and to suggest possible future avenues of research on SA-induced resistance to viruses.

Genetic modification of alternative respiration has differential effects on antimycin A-induced versus salicylic acid-induced resistance to Tobacco mosaic virus.

Salicylic acid (SA), a natural defensive signal chemical, and antimycin A, a cytochrome pathway inhibitor, induce resistance to Tobacco mosaic virus (TMV). Pharmacological evidence suggested signaling during resistance induction by both chemicals involved alternative oxidase (AOX), sole component of the alternative respiratory pathway (AP). Roles of the AP include regulation of intramitochondrial reactive oxygen species and maintenance of metabolic homeostasis. Transgenic tobacco (Nicotiana tabacum) with modified AP capacities (2- to 3-fold increased or decreased) showed no alteration in phenotype with respect to basal susceptibility to TMV or the ability to display SA-induced resistance to systemic viral disease. However, in directly inoculated tissue, antimycin A-induced TMV resistance was inhibited in plants with increased AP capacities, whereas SA and antimycin A-induced resistance was transiently enhanced in plant lines with decreased AP capacities. We conclude that SA-induced TMV resistance results from activation of multiple mechanisms, a subset of which are inducible by antimycin A and influenced by AOX. Other antiviral factors, potentially including the SA-inducible RNA-dependent RNA polymerase, are regulated by AOX-independent mechanisms.

The deposition of suberin lamellae determines the magnitude of cytosolic Ca2+ elevations in root endodermal cells subjected to cooling.

A transient increase in cytosolic Ca2+ concentration ([Ca2+]cyt) is thought to be a prerequisite for an appropriate physiological response to both chilling and salt stress. The [Ca2+]cyt is raised by Ca2+ influx to the cytosol from the apoplast and/or intracellular stores. It has been speculated that different signals mobilise Ca2+ from different stores, but little is known about the origin(s) of the Ca2+ entering the cytosol in response to specific environmental challenges. We have utilised the developmentally regulated suberisation of endodermal cells, which is thought to prevent Ca2+ influx from the apoplast, to ascertain whether Ca2+ influx is required to increase [Ca2+]cyt in response to chilling or salt stress. Perturbations in [Ca2+]cyt were studied in transgenic Arabidopsis thaliana, expressing aequorin fused to a modified yellow fluorescent protein solely in root endodermal cells, during slow cooling of plants from 20 to 0.5 degrees C over 5 min and in response to an acute salt stress (0.333 m NaCl). Only in endodermal cells in the apical 4 mm of the Arabidopsis root did [Ca2+]cyt increase significantly during cooling, and the magnitude of the [Ca2+]cyt elevation elicited by cooling was inversely related to the extent of suberisation of the endodermal cell layer. No [Ca2+]cyt elevations were elicited by cooling in suberised endodermal cells. This is consistent with the hypothesis that suberin lamellae isolate the endodermal cell protoplast from the apoplast and, thereby, prevent Ca2+ influx. By contrast, acute salt stress increased [Ca2+]cyt in endodermal cells throughout the root. These results suggest that [Ca2+]cyt elevations, upon slow cooling, depend absolutely on Ca2+ influx across the plasma membrane, but [Ca2+]cyt elevations in response to acute salt stress do not. They also suggest that Ca2+ release from intracellular stores contributes significantly to increasing [Ca2+]cyt upon acute salt stress.