Plasmodium falciparum CLAG Paralogs All Traffic to the Host Membrane but Knockouts Have Distinct Phenotypes.

Malaria parasites increase their host erythrocyte's permeability to obtain essential nutrients from plasma and facilitate intracellular growth. In the human Plasmodium falciparum pathogen, this increase is mediated by the plasmodial surface anion channel (PSAC) and has been linked to CLAG3, a protein integral to the host erythrocyte membrane and encoded by a member of the conserved clag multigene family. Whether paralogs encoded by other clag genes also insert at the host membrane is unknown; their contributions to PSAC formation and other roles served are also unexplored. Here, we generated transfectant lines carrying epitope-tagged versions of each CLAG. Each paralog is colocalized with CLAG3, with concordant trafficking via merozoite rhoptries to the host erythrocyte membrane of newly invaded erythrocytes. Each also exists within infected cells in at least two forms: an alkaline-extractable soluble form and a form integral to the host membrane. Like CLAG3, CLAG2 has a variant region cleaved by extracellular proteases, but CLAG8 and CLAG9 are protease resistant. Paralog knockout lines, generated through CRISPR/Cas9 transfection, exhibited uncompromised growth in PGIM, a modified medium with higher physiological nutrient levels; this finding is in marked contrast to a recently reported CLAG3 knockout parasite. CLAG2 and CLAG8 knockout lines exhibited compensatory increases in the transcription of the remaining clags and associated rhoph genes, yielding increased PSAC-mediated uptake for specific solutes. We also report on the distinct transport properties of these knockout lines. Similar membrane topologies at the host membrane are consistent with each CLAG paralog contributing to PSAC, but other roles require further examination.

Optimized plasmid loading of human erythrocytes for Plasmodium falciparum DNA transfections.

In vitro modification of Plasmodium falciparum genes is the cornerstone of basic and translational malaria research. Achieved through DNA transfection, these modifications may entail altering protein sequence or abundance. Such experiments are critical for defining the molecular mechanisms of key parasite phenotypes and for validation of drug and vaccine targets. Despite its importance, successful transfection remains difficult and is a resource-intensive, rate-limiting step in P. falciparum research. Here, we report that inefficient loading of plasmid into erythrocytes limits transfection efficacy with commonly used electroporation methods. As these methods also require expensive instrumentation and consumables that are not broadly available, we explored a simpler method based on plasmid loading through hypotonic lysis and resealing of erythrocytes. We used parasite expression of a sensitive NanoLuc reporter for rapid evaluation and optimization of each step. Hypotonic buffer composition, resealing buffer volume and composition, and subsequent incubation affected plasmid retention and successful transfection. While ATP was critical for erythrocyte resealing, addition of Ca++ or glutathione did not improve transfection efficiency, with increasing Ca++ concentrations proving detrimental to outcomes. Compared with either the standard electroporation method or a previously reported hypotonic loading protocol, the optimized method yields greater plasmid loading and higher expression of the NanoLuc reporter 48 h after transfection. It also produced significantly faster outgrowth of parasites in transfections utilizing either episomal expression or CRISPR-Cas9 mediated integration. This new method produces higher P. falciparum transfection efficiency, reduces resource requirements and should accelerate molecular studies of malaria drug and vaccine targets.

Cerebral Protection in Trans-Catheter Aortic Valve Replacement: Review and Contemporary Assessment of Randomized Trial Data.

As the population has aged and as aortic valve therapies have evolved, the use of trans-catheter aortic valve replacement (TAVR) has grown dramatically over the past decade. A well-known complication of percutaneous cardiac intervention is embolic phenomena, and TAVR is among the highest risk procedures for clinical and subclinical stroke. As indications for TAVR expand to lower-risk and ultimately younger patients, the long-term consequences of stroke are amplified. Cerebral embolic protection (CEP) devices have taken a on unique preventative role following the Food and Drug Administration approval of the SentinelTM Cerebral Protection System (CPS). More recently, the PROTECTED TAVR study has spurred extensive debate in the neuro-cardiac community. In this review we describe the contemporary literature regarding stroke risk associated with TAVR, the history and role of CEP devices, a PROTECTED TAVR sub-group analysis, and implications for next steps in the field. Lastly, we explore the unique need for CEP in a younger TAVR population, as well as directions for future research.

Novel Ion Channel Genes in Malaria Parasites.

Ion channels serve many cellular functions including ion homeostasis, volume regulation, signaling, nutrient acquisition, and developmental progression. Although the complex life cycles of malaria parasites necessitate ion and solute flux across membranes, the whole-genome sequencing of the human pathogen Plasmodium falciparum revealed remarkably few orthologs of known ion channel genes. Contrasting with this, biochemical studies have implicated the channel-mediated flux of ions and nutritive solutes across several membranes in infected erythrocytes. Here, I review advances in the cellular and molecular biology of ion channels in malaria parasites. These studies have implicated novel parasite genes in the formation of at least two ion channels, with additional ion channels likely present in various membranes and parasite stages. Computational approaches that rely on homology to known channel genes from higher organisms will not be very helpful in identifying the molecular determinants of these activities. Given their unusual properties, novel molecular and structural features, and essential roles in pathogen survival and development, parasite channels should be promising targets for therapy development.

Nonneoplastic pathology of the appendix: A review article, based on the recent literature.

OBJECTIVES: The appendix, although considered a vestigial organ, is of considerable clinical importance because acute appendicitis is a common medical problem. There are also other disease processes involving the appendix. The appendix is among the first specimens that the pathologist (and surgeon) cuts one's teeth on. Thus, there may be a tendency to underestimate the clinically and prognostically significant appendiceal pathologies. METHODS: We provide a vade mecum of the pathologic features of a wide range of nonneoplastic appendiceal pathologies, with an emphasis on developing a practical approach to grossing, microscopy, and reporting-all with clinical and therapeutic implications. Much of this is based on literature on MEDLINE with reference to years 2008 to 2023, as well as on personal experiences and interpretations. RESULTS: The appendix can harbor a myriad of nonneoplastic pathologies, including infections, inflammations of varying etiologies (including interval appendectomy), endometriosis, diverticulosis, and so on. Chronic appendicitis, Crohn disease, and clinical audit are recurring themes while COVID-19 is a new entity. CONCLUSIONS: Most importantly, all pathologists should appreciate that the appendix is not as "routine" a specimen as one would want to believe.

Antiplasmodial peptaibols act through membrane directed mechanisms.

Our previous study identified 52 antiplasmodial peptaibols isolated from fungi. To understand their antiplasmodial mechanism of action, we conducted phenotypic assays, assessed the in vitro evolution of resistance, and performed a transcriptome analysis of the most potent peptaibol, HZ NPDG-I. HZ NPDG-I and 2 additional peptaibols were compared for their killing action and stage dependency, each showing a loss of digestive vacuole (DV) content via ultrastructural analysis. HZ NPDG-I demonstrated a stepwise increase in DV pH, impaired DV membrane permeability, and the ability to form ion channels upon reconstitution in planar membranes. This compound showed no signs of cross resistance to targets of current clinical candidates, and 3 independent lines evolved to resist HZ NPDG-I acquired nonsynonymous changes in the P. falciparum multidrug resistance transporter, pfmdr1. Conditional knockdown of PfMDR1 showed varying effects to other peptaibol analogs, suggesting differing sensitivity.

Chatbots, generative AI, and scholarly manuscripts: WAME recommendations on chatbots and generative artificial intelligence in relation to scholarly publications.

This statement revises our earlier "WAME Recommendations on ChatGPT and Chatbots in Relation to Scholarly Publications" (January 20, 2023). The revision reflects the proliferation of chatbots and their expanding use in scholarly publishing over the last few months, as well as emerging concerns regarding lack of authenticity of content when using chatbots. These recommendations are intended to inform editors and help them develop policies for the use of chatbots in papers published in their journals. They aim to help authors and reviewers understand how best to attribute the use of chatbots in their work and to address the need for all journal editors to have access to manuscript screening tools. In this rapidly evolving field, we will continue to modify these recommendations as the software and its applications develop.

Esta declaración revisa las anteriores "Recomendaciones de WAME sobre ChatGPT y Chatbots en Relation to Scholarly Publications" (20 de enero de 2023). La revisión refleja la proliferación de chatbots y su creciente uso en las publicaciones académicas en los últimos meses, así como la preocupación por la falta de autenticidad de los contenidos cuando se utilizan chatbots. Estas recomendaciones pretenden informar a los editores y ayudarles a desarrollar políticas para el uso de chatbots en los artículos sometidos en sus revistas. Su objetivo es ayudar a autores y revisores a entender cuál es la mejor manera de atribuir el uso de chatbots en su trabajo y a la necesidad de que todos los editores de revistas tengan acceso a herramientas de selección de manuscritos. En este campo en rápida evolución, seguiremos modificando estas recomendaciones a medida que se desarrollen el software y sus aplicaciones.

NK cell-induced damage to P.falciparum-infected erythrocytes requires ligand-specific recognition and releases parasitophorous vacuoles that are phagocytosed by monocytes in the presence of immune IgG.

Natural killer (NK) cells lyse virus-infected cells and transformed cells through polarized delivery of lytic effector molecules into target cells. We have shown that NK cells lyse Plasmodium falciparum-infected red blood cells (iRBC) via antibody-dependent cellular cytotoxicity (ADCC). A high frequency of adaptive NK cells, with elevated intrinsic ADCC activity, in people chronically exposed to malaria transmission is associated with reduced parasitemia and resistance to disease. How NK cells bind to iRBC and the outcome of iRBC lysis by NK cells has not been investigated. We applied gene ablation in inducible erythrocyte precursors and antibody-blocking experiments with iRBC to demonstrate a central role of CD58 and ICAM-4 as ligands for adhesion by NK cells via CD2 and integrin αMß2, respectively. Adhesion was dependent on opsonization of iRBC by IgG. Live imaging and quantitative flow cytometry of NK-mediated ADCC toward iRBC revealed that damage to the iRBC plasma membrane preceded damage to P. falciparum within parasitophorous vacuoles (PV). PV were identified and tracked with a P.falciparum strain that expresses the PV membrane-associated protein EXP2 tagged with GFP. After NK-mediated ADCC, PV were either found inside iRBC ghosts or released intact and devoid of RBC plasma membrane. Electron microscopy images of ADCC cultures revealed tight NK-iRBC synapses and free vesicles similar in size to GFP+ PV isolated from iRBC lysates by cell sorting. The titer of IgG in plasma of malaria-exposed individuals that bound PV was two orders of magnitude higher than IgG that bound iRBC. This immune IgG stimulated efficient phagocytosis of PV by primary monocytes. The selective NK-mediated damage to iRBC, resulting in release of PV, and subsequent phagocytosis of PV by monocytes may combine for efficient killing and removal of intra-erythrocytic P.falciparum parasite. This mechanism may mitigate the inflammation and malaria symptoms during blood-stage P. falciparum infection.

Quality metrics in academia: time to revisit the rules?

Publication and citation metrics have been used for many years now as apparently objective parameters to evaluate educational institutions as well as individual researchers. A recent report in Science, about the Saveetha Institute of Medical and Technical Sciences (SIMATS), near Chennai, Tamil Nadu [1], highlights concerns about the value and limitations of such metrics in evaluating the importance of research publications, authors, journals and institutions.

Chatbots, generative AI, and scholarly manuscripts: WAME recommendations on chatbots and generative artificial intelligence in relation to scholarly publications

This statement revises our earlier "WAME Recommendations on ChatGPT and Chatbots in Relation to Scholarly Publications" (January 20, 2023). The revision reflects the proliferation of chatbots and their expanding use in scholarly publishing over the last few months, as well as emerging concerns regarding lack of authenticity of content when using chatbots. These recommendations are intended to inform editors and help them develop policies for the use of chatbots in papers published in their journals. They aim to help authors and reviewers understand how best to attribute the use of chatbots in their work and to address the need for all journal editors to have access to manuscript screening tools. In this rapidly evolving field, we will continue to modify these recommendations as the software and its applications develop.

Esta declaración revisa las anteriores "Recomendaciones de WAME sobre ChatGPT y Chatbots en Relation to Scholarly Publications" (20 de enero de 2023). La revisión refleja la proliferación de chatbots y su creciente uso en las publicaciones académicas en los últimos meses, así como la preocupación por la falta de autenticidad de los contenidos cuando se utilizan chatbots. Estas recomendaciones pretenden informar a los editores y ayudarles a desarrollar políticas para el uso de chatbots en los artículos sometidos en sus revistas. Su objetivo es ayudar a autores y revisores a entender cuál es la mejor manera de atribuir el uso de chatbots en su trabajo y a la necesidad de que todos los editores de revistas tengan acceso a herramientas de selección de manuscritos. En este campo en rápida evolución, seguiremos modificando estas recomendaciones a medida que se desarrollen el software y sus aplicaciones.

Hypersonic flow study in a pneumatically operated academic shock tunnel.

A hypersonic shock tunnel is a primary tool used for basic experimental research and may be used in engineering and university courses to study compressible flows involving shock waves. In the present study, a pneumatically operated shock tunnel is demonstrated for hypersonic flow studies. The high-pressure nitrogen gas is used to drive a pneumatic cylinder, which is used to burst the thin metal diaphragms. Tunnel-free stream conditions are quantified using the measured pressure values and by applying shock tube relations. The free-stream Mach number of 5.5-7.2 is achieved by varying the bursting pressure and test gas pressure from 2.1 to 4.5 bars and 0.2 to 0.5 bar, respectively. The simulation is performed and the shock standoff distance quantified, and the stagnation pressures measured. The results demonstrate that the pneumatically operated tunnel enhanced operation capacity compared to the manually operated tunnel and well suits the academic hypersonic research and developmental activities.

Conditional permeabilization of the P. falciparum plasma membrane in infected cells links cation influx to reduced membrane integrity.

The intracellular human malaria parasite, Plasmodium falciparum, uses the PfATP4 cation pump to maintain Na+ and H+ homeostasis in parasite cytosol. PfATP4 is the target of advanced antimalarial leads, which produce many poorly understood metabolic disturbances within infected erythrocytes. Here, we expressed the mammalian ligand-gated TRPV1 ion channel at the parasite plasma membrane to study ion regulation and examine the effects of cation leak. TRPV1 expression was well-tolerated, consistent with negligible ion flux through the nonactivated channel. TRPV1 ligands produced rapid parasite death in the transfectant line at their activating concentrations, but were harmless to the wild-type parent. Activation triggered cholesterol redistribution at the parasite plasma membrane, reproducing effects of PfATP4 inhibitors and directly implicating cation dysregulation in this process. In contrast to predictions, TRPV1 activation in low Na+ media accentuated parasite killing but a PfATP4 inhibitor had unchanged efficacy. Selection of a ligand-resistant mutant revealed a previously uncharacterized G683V mutation in TRPV1 that occludes the lower channel gate, implicating reduced permeability as a mechanism for parasite resistance to antimalarials targeting ion homeostasis. Our findings provide key insights into malaria parasite ion regulation and will guide mechanism-of-action studies for advanced antimalarial leads that act at the host-pathogen interface.

Lacunae in Laboratory Medicine Services and in Pathology Education in Medical Schools in India.

CONTEXT.­: Laboratories of many medical college hospitals in India do not offer important diagnostic tests, most of which are routine in the West. This detracts from the service as well as the educational function of the college. OBJECTIVES.­: To provide the background to pathology and laboratory medicine services and education in India, and to create a questionnaire that will put the lack of tertiary care laboratory services in perspective. This article will help illustrate the lacunae in laboratory medicine services and in the education of students. For this, we present information on the health services and pathology education facilities in India. We propose a questionnaire comprising 30 questions in various disciplines in pathology and laboratory medicine. These questions will help administrators and bureaucrats evaluate the status of the laboratories with respect to the services provided. DATA SOURCES.­: Sources include Web sites of the government of India, including that of the National Accreditation Board for Testing and Calibration Laboratories; indexed medical journal articles; and standard books and white papers on health care in India. We also used our personal experiences and interpretations of the laboratory and medical education sector in India. CONCLUSIONS.­: Medical colleges in India need to offer specialized diagnostic services if they are to achieve the targets of universal health care as well as turning out competent doctors. The agencies responsible for health care in India should use the questionnaire as a first step toward improving laboratory services. Other low- and middle-income countries should also adopt this method.

A robust fluorescence-based assay for human erythrocyte Ca++ efflux suitable for high-throughput inhibitor screens.

Intracellular calcium is maintained at very low concentrations through the action of PMCA Ca++ extrusion pumps. Although much of our knowledge about these Ca++ extrusion pumps derives from studies with human erythrocytes, kinetic studies of Ca++ transport for these cells are limited to radioisotope flux measurements. Here, we developed a robust, microplate-based assay for erythrocyte Ca++ efflux using extracellular fluorescent Ca++ indicators. We optimized Ca++ loading with the A23187 ionophore, established conditions for removal of the ionophore, and adjusted fluorescent dye sensitivity by addition of extracellular EGTA to allow continuous tracking of Ca++ efflux. Efflux kinetics were accelerated by glucose and inhibited in a dose-dependent manner by the nonspecific inhibitor vanadate, revealing that Ca++ pump activity can be tracked in a 384-well microplate format. These studies enable radioisotope-free kinetic measurements of the Ca++ pump and should facilitate screens for specific inhibitors of this essential transport activity.