Targeting glutamine metabolism rescues mice from late-stage cerebral malaria.

The most deadly complication of Plasmodium falciparum infection is cerebral malaria (CM) with a case fatality rate of 15-25% in African children despite effective antimalarial chemotherapy. There are no adjunctive treatments for CM, so there is an urgent need to identify new targets for therapy. Here we show that the glutamine analog 6-diazo-5-oxo-L-norleucine (DON) rescues mice from CM when administered late in the infection a time at which mice already are suffering blood-brain barrier dysfunction, brain swelling, and hemorrhaging accompanied by accumulation of parasite-specific CD8(+) effector T cells and infected red blood cells in the brain. Remarkably, within hours of DON treatment mice showed blood-brain barrier integrity, reduced brain swelling, decreased function of activated effector CD8(+) T cells in the brain, and levels of brain metabolites that resembled those in uninfected mice. These results suggest DON as a strong candidate for an effective adjunctive therapy for CM in African children.

Effects of an early conformational switch defect during ϕX174 morphogenesis are belatedly manifested late in the assembly pathway.

C-terminal, aromatic amino acids in the ϕX174 internal scaffolding protein B mediate conformational switches in the viral coat protein. These switches direct the coat protein through early assembly. In addition to the aromatic amino acids, two acidic residues, D111 and E113, form salt bridges with basic, coat protein side chains. Although salt bridge formation did not appear to be critical for assembly, the substitution of an aromatic amino acid for D111 produced a lethal phenotype. This side chain is uniquely oriented toward the center of the coat-scaffolding binding pocket, which is heavily dominated by aromatic ring-ring interactions. Thus, the D111Y substitution may restructure pocket contacts. Previously characterized B(-) mutants blocked assembly before procapsid formation. However, the D111Y mutant produced an assembled particle, which contained the structural and external scaffolding proteins but lacked protein B and DNA. A suppressor within the external scaffolding protein, which mediates the later stages of particle morphogenesis, restored viability. The unique formation of a postprocapsid particle and the novel suppressor may be indicative of a novel B protein function. However, genetic data suggest that the particle represents the delayed manifestation of an early assembly error. This seemingly late-acting defect was rescued by previously characterized suppressors of early, preprocapsid, B(-) assembly mutations, which act on the level of coat protein flexibility. Likewise, the newly isolated suppressor in the external scaffolding protein also exhibited a global suppressing phenotype. Thus, the off-pathway product isolated from infected cells may not accurately reflect the temporal nature of the initial defect.

Enhancing Patient Communication With Chat-GPT in Radiology: Evaluating the Efficacy and Readability of Answers to Common Imaging-Related Questions.

PURPOSE: To assess ChatGPT's accuracy, relevance, and readability in answering patients' common imaging-related questions and examine the effect of a simple prompt. METHODS: A total of 22 imaging-related questions were developed from categories previously described as important to patients, as follows: safety, the radiology report, the procedure, preparation before imaging, meaning of terms, and medical staff. These questions were posed to ChatGPT with and without a short prompt instructing the model to provide an accurate and easy-to-understand response for the average person. Four board-certified radiologists evaluated the answers for accuracy, consistency, and relevance. Two patient advocates also reviewed responses for their utility for patients. Readability was assessed using the Flesch Kincaid Grade Level. Statistical comparisons were performed using χ2 and paired t tests. RESULTS: A total of 264 answers were assessed for both unprompted and prompted questions. Unprompted responses were accurate 83% of the time (218 of 264), which did not significantly change for prompted responses (87% [229 of 264]; P = .2). The consistency of the responses increased from 72% (63 of 88) to 86% (76 of 88) when prompts were given (P = .02). Nearly all responses (99% [261 of 264]) were at least partially relevant for both question types. Fewer unprompted responses were considered fully relevant at 67% (176 of 264), although this increased significantly to 80% when prompts were given (210 of 264; P = .001). The average Flesch Kincaid Grade Level was high at 13.6 [CI, 12.9-14.2], unchanged with the prompt (13.0 [CI, 12.41-13.60], P = .2). None of the responses reached the eighth-grade readability level recommended for patient-facing materials. DISCUSSION: ChatGPT demonstrates the potential to respond accurately, consistently, and relevantly to patients' imaging-related questions. However, imperfect accuracy and high complexity necessitate oversight before implementation. Prompts reduced response variability and yielded more-targeted information, but they did not improve readability. ChatGPT has the potential to increase accessibility to health information and streamline the production of patient-facing educational materials; however, its current limitations require cautious implementation and further research.

Large Language Model Use in Radiology Residency Applications: Unwelcomed but Inevitable.

OBJECTIVE: This study explores radiology program directors' perspectives on the impact of large language model (LLM) use among residency applicants to craft personal statements. METHODS: Eight program directors from the Radiology Residency Education Research Alliance (RRERA) participated in a mixed-methods study, which included a survey regarding impressions of AI-generated personal statements and focus group discussions (July 2023). Each director reviewed four personal statement variations for five applicants, blinded to author type: the original and three ChatGPT-4.0 versions generated with varying prompts, aggregated for analysis. A 5-point Likert scale surveyed the writing quality, including voice, clarity, engagement, organization, and the perceived origin of each statement. An experienced qualitative researcher facilitated focus group discussions. Data analysis was performed using a rapid analytic approach with a coding template capturing key areas related to residency applications. RESULTS: GPT-generated statement (GPT) ratings were more often average or worse in quality (56%, 268/475) than ratings of human-authored statements (Hu) (29% [45/160]). Although reviewers were not confident in their ability to distinguish the origin of personal statements, they did so reliably and consistently, identifying the human-authored personal statements at 95% (38/40) as probably or definitely original. Focus group discussions highlighted the inevitable use of AI in crafting personal statements and concerns about its impact on the authenticity and the value of the personal statement in residency selections. Program directors were divided on the appropriate use and regulation of AI. DISCUSSION: Radiology residency program directors rated LLM-generated personal statements as lower in quality and expressed concern about the loss of the applicant's voice but acknowledged the inevitability of increased AI use in the generation of application statements.

Conformational switch-defective X174 internal scaffolding proteins kinetically trap assembly intermediates before procapsid formation.

Conformational switching is an overarching paradigm in which to describe scaffolding protein-mediated virus assembly. However, rapid morphogenesis with small assembly subunits hinders the isolation of early morphogenetic intermediates in most model systems. Consequently, conformational switches are often defined by comparing the structures of virions, procapsids and aberrantly assembled particles. In contrast, X174 morphogenesis proceeds through at least three preprocapsid intermediates, which can be biochemically isolated. This affords a detailed analysis of early morphogenesis and internal scaffolding protein function. Amino acid substitutions were generated for the six C-terminal, aromatic amino acids that mediate most coat-internal scaffolding protein contacts. The biochemical characterization of mutant assembly pathways revealed two classes of molecular defects, protein binding and conformational switching, a novel phenotype. The conformational switch mutations kinetically trapped assembly intermediates before procapsid formation. Although mutations trapped different particles, they shared common second-site suppressors located in the viral coat protein. This suggests a fluid assembly pathway, one in which the scaffolding protein induces a single, coat protein conformational switch and not a series of sequential reactions. In this model, an incomplete or improper switch would kinetically trap intermediates.

Evidence for an adverse impact of remote readouts on radiology resident productivity: Implications for training and clinical practice.

After their rapid adoption at the onset of the coronavirus pandemic, remote case reviews (remote readouts) between diagnostic radiology residents and their attendings have persisted in an increasingly remote workforce, despite relaxing social distancing guidelines. Our objective was to evaluate the impact of the transition to remote readouts on resident case volumes after the recovery of institutional volumes. We tabulated radiology reports co-authored by first-to-third-year radiology residents (R1-R3) between July 1 and December 31 of the first pandemic year, 2020, and compared to the prior two pre-pandemic years. Half-years were analyzed because institutional volumes recovered by July 2020. Resident volumes were normalized to rotations, which were in divisions categorized by the location of the supervising faculty during the pandemic period; in 'remote' divisions, all faculty worked off-site, whereas 'hybrid' divisions had a mix of attendings working on-site and remotely. All residents worked on-site. Data analysis was performed with Student's t test and multivariate linear regression. The largest drops in total case volume occurred in the two remote divisions (38% [6,086 to 3,788], and 26% [11,046 to 8,149]). None of the hybrid divisions with both in-person and remote supervision decreased by more than 5%. With multivariate regression, a resident assigned to a standardized remote rotation in 2020 would complete 32% (253 to 172) fewer studies than in identical pre-pandemic rotations (coefficent of -81.6, p = .005) but would be similar for hybrid rotations. R1 residents would be expected to interpret 40% fewer (180 to 108) cases on remote rotations during the pandemic (coefficient of -72.3, p = .007). No significant effect was seen for R2 or R3 residents (p = .099 and p = .29, respectively). Radiology residents interpreted fewer studies during remote rotations than on hybrid rotations that included in-person readouts. As resident case volume is correlated with clinical performance and board pass rate, monitoring the readout model for downstream educational effects is essential. Until evidence shows that educational outcomes remain unchanged, radiology residencies may wish to preserve in-person resident readouts, particularly for junior residents.

Surrogates of Muscle Mass on Cardiac MRI Correlate with Exercise Capacity in Patients with Fontan Circulation.

BACKGROUND: Sarcopenia is an increasingly recognized marker of frailty in cardiac patients. Patients with a history of congenital heart disease and Fontan procedure have a higher risk of developing progressive muscle wasting. Our objective was to determine if we could use routine cardiac MRI (CMR) for the surveillance of muscle wasting. METHODS: A retrospective study of all Fontan patients (n = 75) was conducted at our institution, with CMR performed from 2010 to 2022 and exercise stress testing performed within 12 months (4.3 ± 4.2 months). The skeletal muscle area (SMA) for the posterior paraspinal and anterior thoracic muscles were traced and indexed for body surface area (BSA). Patients were stratified by percentile into the upper and lower quartiles, and the two groups were compared. Multivariable regression was performed to control for sex and age. RESULTS: There was a significant positive association of both anterior (r = 0.34, p = 0.039) and paraspinal (r = 0.43, p = 0.007) SMA to peak VO2. Similarly, paraspinal but not anterior SMA was negatively associated with the VE/VCO2 (r = -0.45, p = 0.006). The upper quartile group had significantly more males (18/19 vs. 8/20; p = 0.0003) and demonstrated a significantly higher peak VO2 (32.2 ± 8.5 vs. 23.8 ± 4.7, p = 0.009), a higher peak RER (1.2 ± 0.1 vs. 1.1 ± 0.04, p = 0.007), and a significantly lower VE/VCO2 (32.9 ± 3.6 vs. 40.2 ± 6.2, p = 0.006) compared to the lowest quartile. The association of SMA to VO2 peak and VE/VCO2 was redemonstrated after controlling for sex and age. CONCLUSION: Thoracic skeletal muscle area may be an effective surrogate of muscle mass and is correlated to several measures of cardiorespiratory fitness post-Fontan. CMR would be an effective tool for the surveillance of sarcopenia in post-Fontan patients given its accessibility and routine use in these patients.

Deep Learning Prediction of Voxel-Level Liver Stiffness in Patients with Nonalcoholic Fatty Liver Disease.

PURPOSE: To reconstruct virtual MR elastography (MRE) images based on traditional MRI inputs with a machine learning algorithm. MATERIALS AND METHODS: In this single-institution, retrospective study, 149 patients (mean age, 58 years ± 12 [standard deviation]; 71 men) with nonalcoholic fatty liver disease who underwent MRI and MRE between January 2016 and January 2019 were evaluated. Nine conventional MRI sequences and clinical data were used to train a convolutional neural network to reconstruct MRE images at the per-voxel level. The architecture was further modified to accept multichannel three-dimensional inputs and to allow inclusion of clinical and demographic information. Liver stiffness and fibrosis category (F0 [no fibrosis] to F4 [significant fibrosis]) of reconstructed images were assessed by using voxel- and patient-level agreement by correlation, sensitivity, and specificity calculations; in addition, classification by receiver operator characteristic analyses was performed, and Dice score was used to evaluate hepatic stiffness locality. RESULTS: The model for predicting liver stiffness incorporated four image sequences (precontrast T1-weighted liver acquisition with volume acquisition [LAVA] water and LAVA fat, 120-second-delay T1-weighted LAVA water, and single-shot fast spin-echo T2 weighted) and clinical data. The model had a patient-level and voxel-level correlation of 0.50 ± 0.05 and 0.34 ± 0.03, respectively. By using a stiffness threshold of 3.54 kPa to make a binary classification into no fibrosis or mild fibrosis (F0-F1) versus clinically significant fibrosis (F2-F4), the model had sensitivity of 80% ± 4, specificity of 75% ± 5, accuracy of 78% ± 3, area under the receiver operating characteristic curve of 84 ± 0.04, and a Dice score of 0.74. CONCLUSION: The generation of virtual elastography images is feasible by using conventional MRI and clinical data with a machine learning algorithm.Keywords: MR Imaging, Abdomen/GI, Liver, Cirrhosis, Computer Applications/Virtual Imaging, Experimental Investigations, Feature Detection, Classification, Reconstruction Algorithms, Supervised Learning, Convolutional Neural Network (CNN) Supplemental material is available for this article. © RSNA, 2021.

Malaria parasite detection and cell counting for human and mouse using thin blood smear microscopy.

Despite the remarkable progress that has been made to reduce global malaria mortality by 29% in the past 5 years, malaria is still a serious global health problem. Inadequate diagnostics is one of the major obstacles in fighting the disease. An automated system for malaria diagnosis can help to make malaria screening faster and more reliable. We present an automated system to detect and segment red blood cells (RBCs) and identify infected cells in Wright-Giemsa stained thin blood smears. Specifically, using image analysis and machine learning techniques, we process digital images of thin blood smears to determine the parasitemia in each smear. We use a cell extraction method to segment RBCs, in particular overlapping cells. We show that a combination of RGB color and texture features outperforms other features. We evaluate our method on microscopic blood smear images from human and mouse and show that it outperforms other techniques. For human cells, we measure an absolute error of 1.18% between the true and the automatic parasite counts. For mouse cells, our automatic counts correlate well with expert and flow cytometry counts. This makes our system the first one to work for both human and mouse.

Inhibiting the Mammalian target of rapamycin blocks the development of experimental cerebral malaria.

UNLABELLED: Malaria is an infectious disease caused by parasites of several Plasmodium spp. Cerebral malaria (CM) is a common form of severe malaria resulting in nearly 700,000 deaths each year in Africa alone. At present, there is no adjunctive therapy for CM. Although the mechanisms underlying the pathogenesis of CM are incompletely understood, it is likely that both intrinsic features of the parasite and the human host's immune response contribute to disease. The kinase mammalian target of rapamycin (mTOR) is a central regulator of immune responses, and drugs that inhibit the mTOR pathway have been shown to be antiparasitic. In a mouse model of CM, experimental CM (ECM), we show that the mTOR inhibitor rapamycin protects against ECM when administered within the first 4 days of infection. Treatment with rapamycin increased survival, blocked breakdown of the blood-brain barrier and brain hemorrhaging, decreased the influx of both CD4(+) and CD8(+) T cells into the brain and the accumulation of parasitized red blood cells in the brain. Rapamycin induced marked transcriptional changes in the brains of infected mice, and analysis of transcription profiles predicted that rapamycin blocked leukocyte trafficking to and proliferation in the brain. Remarkably, animals were protected against ECM even though rapamycin treatment significantly increased the inflammatory response induced by infection in both the brain and spleen. These results open a new avenue for the development of highly selective adjunctive therapies for CM by targeting pathways that regulate host and parasite metabolism. IMPORTANCE: Malaria is a highly prevalent infectious disease caused by parasites of several Plasmodium spp. Malaria is usually uncomplicated and resolves with time; however, in about 1% of cases, almost exclusively among young children, malaria becomes severe and life threatening, resulting in nearly 700,000 deaths each year in Africa alone. Among the most severe complications of Plasmodium falciparum infection is cerebral malaria with a fatality rate of 15 to 20%, despite treatment with antimalarial drugs. Cerebral malaria takes a second toll on African children, leaving survivors at high risk of debilitating neurological defects. At present, we have no effective adjunctive therapies for cerebral malaria, and developing such therapies would have a large impact on saving young lives in Africa. Here we report results that open a new avenue for the development of highly selective adjunctive therapies for cerebral malaria by targeting pathways that regulate host and parasite metabolism.

Tempol, an intracellular antioxidant, inhibits tissue factor expression, attenuates dendritic cell function, and is partially protective in a murine model of cerebral malaria.

BACKGROUND: The role of intracellular radical oxygen species (ROS) in pathogenesis of cerebral malaria (CM) remains incompletely understood. METHODS AND FINDINGS: We undertook testing Tempol--a superoxide dismutase (SOD) mimetic and pleiotropic intracellular antioxidant--in cells relevant to malaria pathogenesis in the context of coagulation and inflammation. Tempol was also tested in a murine model of CM induced by Plasmodium berghei Anka infection. Tempol was found to prevent transcription and functional expression of procoagulant tissue factor in endothelial cells (ECs) stimulated by lipopolysaccharide (LPS). This effect was accompanied by inhibition of IL-6, IL-8, and monocyte chemoattractant protein (MCP-1) production. Tempol also attenuated platelet aggregation and human promyelocytic leukemia HL60 cells oxidative burst. In dendritic cells, Tempol inhibited LPS-induced production of TNF-α, IL-6, and IL-12p70, downregulated expression of co-stimulatory molecules, and prevented antigen-dependent lymphocyte proliferation. Notably, Tempol (20 mg/kg) partially increased the survival of mice with CM. Mechanistically, treated mice had lowered plasma levels of MCP-1, suggesting that Tempol downmodulates EC function and vascular inflammation. Tempol also diminished blood brain barrier permeability associated with CM when started at day 4 post infection but not at day 1, suggesting that ROS production is tightly regulated. Other antioxidants-such as α-phenyl N-tertiary-butyl nitrone (PBN; a spin trap), MnTe-2-PyP and MnTBAP (Mn-phorphyrin), Mitoquinone (MitoQ) and Mitotempo (mitochondrial antioxidants), M30 (an iron chelator), and epigallocatechin gallate (EGCG; polyphenol from green tea) did not improve survival. By contrast, these compounds (except PBN) inhibited Plasmodium falciparum growth in culture with different IC50s. Knockout mice for SOD1 or phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (gp91(phox-/-)) or mice treated with inhibitors of SOD (diethyldithiocarbamate) or NADPH oxidase (diphenyleneiodonium) did not show protection or exacerbation for CM. CONCLUSION: Results with Tempol suggest that intracellular ROS contribute, in part, to CM pathogenesis. Therapeutic targeting of intracellular ROS in CM is discussed.