Systemic and iatrogenic factors contribute to the development of severe hypernatraemia in vulnerable inpatients.

OBJECTIVES: To determine all-cause in-hospital mortality associated with severe hypernatraemia and the causes, comorbidities, time to treatment, discharge destination and postdischarge mortality. DESIGN: Retrospective observational cohort study. PATIENTS: Severe hypernatraemia, (sodium concentration ≥ 155 mmol/L), at any time during a tertiary hospital admission in Melbourne, Australia, 1 January 2019 to 31 December 2019 (pre-COVID19). MEASUREMENTS: Deaths, Charlson Comorbidity Index (CCI), hypernatraemia causes, time to treatment, discharge destination. RESULTS: One hundred and one inpatients: 64 community-acquired, 37 hospital-acquired. In-hospital mortality was 38%, but cumulative mortality was 65% by 1 month after discharge, with only a minor further increase at 6 and 12 months. After adjusting for peak sodium concentration, the community acquired group had significantly reduced odds of in-hospital mortality (odds ratio 0.15, 95% confidence interval [0.04-0.54], p = .003). Iatrogenic factors were present in 57% (21/37) of the hospital-acquired group. Only 55% of all cases received active sodium directed treatment. Time to start treatment did not affect outcomes. High levels of comorbidity were present, median CCI (IQR) was 6 (5-8) in the community and 5 (4-7) in the hospital group. Dementia prevalence was higher in the community group, 66% (42/64) versus 19% (7/37) (p = .001). Infection was the most common precipitant with 52% (33/64) in the community and 32% (12/37) in the hospital group. Of the survivors, 32% who had been living independently required residential care after discharge. CONCLUSIONS: Mortality was high and loss of independence in survivors common. To potentially improve outcomes, hypernatraemia-specific guidelines should be formulated and efforts made to reduce system and iatrogenic factors.

Transmission of SARS-CoV-2 in domestic cats imposes a narrow bottleneck.

The evolutionary mechanisms by which SARS-CoV-2 viruses adapt to mammalian hosts and, potentially, undergo antigenic evolution depend on the ways genetic variation is generated and selected within and between individual hosts. Using domestic cats as a model, we show that SARS-CoV-2 consensus sequences remain largely unchanged over time within hosts, while dynamic sub-consensus diversity reveals processes of genetic drift and weak purifying selection. We further identify a notable variant at amino acid position 655 in Spike (H655Y), which was previously shown to confer escape from human monoclonal antibodies. This variant arises rapidly and persists at intermediate frequencies in index cats. It also becomes fixed following transmission in two of three pairs. These dynamics suggest this site may be under positive selection in this system and illustrate how a variant can quickly arise and become fixed in parallel across multiple transmission pairs. Transmission of SARS-CoV-2 in cats involved a narrow bottleneck, with new infections founded by fewer than ten viruses. In RNA virus evolution, stochastic processes like narrow transmission bottlenecks and genetic drift typically act to constrain the overall pace of adaptive evolution. Our data suggest that here, positive selection in index cats followed by a narrow transmission bottleneck may have instead accelerated the fixation of S H655Y, a potentially beneficial SARS-CoV-2 variant. Overall, our study suggests species- and context-specific adaptations are likely to continue to emerge. This underscores the importance of continued genomic surveillance for new SARS-CoV-2 variants as well as heightened scrutiny for signatures of SARS-CoV-2 positive selection in humans and mammalian model systems.

Integrating Functional Imaging and Molecular Profiling for Optimal Treatment Selection in Neuroendocrine Neoplasms (NEN).

PURPOSE OF REVIEW: Gastroenteropancreatic NEN (GEP-NEN) are group of malignancies with significant clinical, anatomical and molecular heterogeneity. High-grade GEP-NEN in particular present unique management challenges. RECENT FINDINGS: In the current era, multidisciplinary management with access to a combination of functional imaging and targeted molecular profiling can provide important disease characterisation, guide individualised management and improve patient outcome. Multiple treatment options are now available, and combination and novel therapies are being explored in clinical trials. Precision medicine is highly relevant for a heterogenous disease like NEN. The integration of dual-tracer functional PET/CT imaging, molecular histopathology and genomic data has the potential to be used to gain a more comprehensive understanding of an individual patient's disease biology for precision diagnosis, prognostication and optimal treatment allocation.

Empiric radioiodine for hyperthyroidism: Outcomes, prescribing patterns, and its place in the modern era of theranostics.

BACKGROUND: The modern era of radioiodine (I-131) theranostics for metastatic differentiated thyroid cancer requires us to rationalize the role of traditional empiric prescription in nonmalignant thyroid disease. We currently practice empiric I-131 prescription for treatment of hyperthyroidism. This study aims to assess outcomes after treatment of hyperthyroidism by empiric I-131 prescription at our centre, evaluate factors that impact on outcomes and prescribing practice, and gain insight into whether there is a place for theranostically-guided prescription in hyperthyroidism. PATIENTS AND METHODS: A retrospective review was undertaken of all patients with Graves' disease, toxic multinodular goitre (MNG) and toxic adenoma treated with I-131 between 2016 and 2021. Associations between clinical or scintigraphic variables and remission (euthyroid or hypothyroid) or persistence of hyperthyroidism at follow-up were performed using standard t test as well as Pearson's product correlation. RESULTS: Of 146 patients with a mean follow-up of 13.6 months, 80.8% achieved remission of hyperthyroidism. This was highest in toxic nodules (90.1%), compared with Graves' disease (73.8%) and toxic MNG (75.5%). In patients with Graves' disease, higher administered activity was associated with remission (p = .035). There was a weak inverse correlation between the Tc-99m pertechnetate uptake vs prescribed activity in Graves' disease (r = -0.33; p = .009). Only one patient (0.7%) had an I-131 induced flare of thyrotoxicosis. CONCLUSION: Traditional empiric I-131 prescription is a safe and effective treatment of hyperthyroidism and suitable for most patients. However, there may be a role for personalized I-131 prescription by theranostic guidance in selected patients with high thyroid hyperactivity.

Managing hyponatraemia secondary to primary polydipsia: beware too rapid correction of hyponatraemia.

We describe three cases of severe hyponatraemia in the setting of primary polydipsia that were managed in our centre in 2016. Despite receiving different solute loads, large volume diuresis and rapid correction of serum sodium occurred in all cases. Given the potentially catastrophic consequence of osmotic demyelination, we highlight the judicious use of desmopressin and hypotonic fluid infusion to mitigate sodium overcorrection in this setting.

Multi-omic analysis of SDHB-deficient pheochromocytomas and paragangliomas identifies metastasis and treatment-related molecular profiles.

Hereditary SDHB-mutant pheochromocytomas (PC) and paragangliomas (PG) are rare tumours with a high propensity to metastasize although their clinical behaviour is unpredictable. To characterize the genomic landscape of these tumours and identify metastasis biomarkers, we performed multi-omic analysis on 94 tumours from 79 patients using seven molecular methods. Sympathetic (chromaffin cell) and parasympathetic (non-chromaffin cell) PCPG had distinct molecular profiles reflecting their cell-of-origin and biochemical profile. TERT and ATRX-alterations were associated with metastatic PCPG and these tumours had an increased mutation load, and distinct transcriptional and telomeric features. Most PCPG had quiet genomes with some rare co-operative driver events observed, including EPAS1/HIF-2α mutations. Two mechanisms of acquired resistance to DNA alkylating chemotherapies were also detected - MGMT overexpression and mismatch repair-deficiency causing hypermutation. Our comprehensive multi-omic analysis of SDHB-mutant PCPG therefore identified features of metastatic disease and treatment response, expanding our understanding of these rare neuroendocrine tumours.

Hypervitaminosis D Secondary to a CYP24A1 Loss-of-Function Mutation: An Unusual Cause of Hypercalcemia in Two Siblings.

Hypervitaminosis D as a cause of hypercalcemia may be due to vitamin D intoxication, granulomatous diseases, or abnormalities of vitamin D metabolism. The CYP24A1 gene encodes for the 24-hydroxylase enzyme, which is responsible for the catabolism of 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D). Mutations in CYP24A1 can result in elevated 1,25(OH)2D causing parathyroid hormone (PTH)-independent hypercalcemia, hypercalciuria, nephrolithiasis, and nephrocalcinosis. We present the cases of two siblings exhibiting hypercalcemia secondary to a CYP24A1 loss-of-function mutation. Case 1 presented initially with PTH-dependent hypercalcemia, with localization of a left upper parathyroid adenoma on parathyroid technetium sestamibi (99mTc-MIBI) uptake study. Despite parathyroidectomy (180 mg adenoma), hypercalcemia, hypercalciuria, and low normal PTH levels persisted. A repeat parathyroid 99mTc-MIBI uptake study localized a second adenoma and a right inferior parathyroidectomy was performed (170 mg adenoma). PTH subsequently became undetectable, however hypercalcemia and hypercalciuria persisted. A new presentation of PTH-independent hypercalcemia found to be secondary to a CYP24A1 loss-of-function mutation in his sibling, Case 2, signaled the underlying cause. Cascade testing confirmed both siblings were homozygous for the pathogenic variant c.1186C>T, p.Arg396Trp (R396W) of CYP24A1 (NM_000782.5). In clinical practice CYP24A1 loss-of-function mutations should be considered in patients presenting with PTH-independent hypercalcemia, hypercalciuria, and 1,25(OH)2D levels in the upper normal or elevated range. Although in our case assays of 24,25(OH)2D were not available, calculation of the 25(OH)D:24,25(OH)2D ratio can assist in the diagnostic process. Possible treatments to manage the risk of hypercalcemia in patients with a CYP24A1 loss-of-function mutation include avoidance of vitamin D oversupplementation and excessive sun exposure. Hydration and bisphosphonate therapy can be useful in managing the hypercalcemia. Although not utilized in our cases, treatment with ketoconazole, fluconazole, and rifampicin have been described as potential therapeutic options. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Wolbachia -mediated resistance to Zika virus infection in Aedes aegypti is dominated by diverse transcriptional regulation and weak evolutionary pressures.

A promising candidate for arbovirus control and prevention relies on replacing arbovirus-susceptible Aedes aegypti populations with mosquitoes that have been colonized by the intracellular bacterium Wolbachia and thus have a reduced capacity to transmit arboviruses. This reduced capacity to transmit arboviruses is mediated through a phenomenon referred to as pathogen blocking. Pathogen blocking has primarily been proposed as a tool to control dengue virus (DENV) transmission, however it works against a range of viruses, including Zika virus (ZIKV). Despite years of research, the molecular mechanisms underlying pathogen blocking still need to be better understood. Here, we used RNA-seq to characterize mosquito gene transcription dynamics in Ae. aegypti infected with the w Mel strain of Wolbachia that are being released by the World Mosquito Program in Medellín, Colombia. Comparative analyses using ZIKV-infected, uninfected tissues, and mosquitoes without Wolbachia revealed that the influence of w Mel on mosquito gene transcription is multifactorial. Importantly, because Wolbachia limits, but does not completely prevent, replication of ZIKV and other viruses in coinfected mosquitoes, there is a possibility that these viruses could evolve resistance to pathogen blocking. Therefore, to understand the influence of Wolbachia on within-host ZIKV evolution, we characterized the genetic diversity of molecularly barcoded ZIKV virus populations replicating in Wolbachia -infected mosquitoes and found that within-host ZIKV evolution was subject to weak purifying selection and, unexpectedly, loose anatomical bottlenecks in the presence and absence of Wolbachia . Together, these findings suggest that there is no clear transcriptional profile associated with Wolbachia -mediated ZIKV restriction, and that there is no evidence for ZIKV escape from this restriction in our system. Author Summary: When Wolbachia bacteria infect Aedes aegypti mosquitoes, they dramatically reduce the mosquitoes' susceptibility to infection with a range of arthropod-borne viruses, including Zika virus (ZIKV). Although this pathogen-blocking effect has been widely recognized, its mechanisms remain unclear. Furthermore, because Wolbachia limits, but does not completely prevent, replication of ZIKV and other viruses in coinfected mosquitoes, there is a possibility that these viruses could evolve resistance to Wolbachia -mediated blocking. Here, we use host transcriptomics and viral genome sequencing to examine the mechanisms of ZIKV pathogen blocking by Wolbachia and viral evolutionary dynamics in Ae. aegypti mosquitoes. We find complex transcriptome patterns that do not suggest a single clear mechanism for pathogen blocking. We also find no evidence that Wolbachia exerts detectable selective pressures on ZIKV in coinfected mosquitoes. Together our data suggest that it may be difficult for ZIKV to evolve Wolbachia resistance, perhaps due to the complexity of the pathogen blockade mechanism.

Wolbachia-mediated resistance to Zika virus infection in Aedes aegypti is dominated by diverse transcriptional regulation and weak evolutionary pressures.

A promising candidate for arbovirus control and prevention relies on replacing arbovirus-susceptible Aedes aegypti populations with mosquitoes that have been colonized by the intracellular bacterium Wolbachia and thus have a reduced capacity to transmit arboviruses. This reduced capacity to transmit arboviruses is mediated through a phenomenon referred to as pathogen blocking. Pathogen blocking has primarily been proposed as a tool to control dengue virus (DENV) transmission, however it works against a range of viruses, including Zika virus (ZIKV). Despite years of research, the molecular mechanisms underlying pathogen blocking still need to be better understood. Here, we used RNA-seq to characterize mosquito gene transcription dynamics in Ae. aegypti infected with the wMel strain of Wolbachia that are being released by the World Mosquito Program in Medellín, Colombia. Comparative analyses using ZIKV-infected, uninfected tissues, and mosquitoes without Wolbachia revealed that the influence of wMel on mosquito gene transcription is multifactorial. Importantly, because Wolbachia limits, but does not completely prevent, replication of ZIKV and other viruses in coinfected mosquitoes, there is a possibility that these viruses could evolve resistance to pathogen blocking. Therefore, to understand the influence of Wolbachia on within-host ZIKV evolution, we characterized the genetic diversity of molecularly barcoded ZIKV virus populations replicating in Wolbachia-infected mosquitoes and found that within-host ZIKV evolution was subject to weak purifying selection and, unexpectedly, loose anatomical bottlenecks in the presence and absence of Wolbachia. Together, these findings suggest that there is no clear transcriptional profile associated with Wolbachia-mediated ZIKV restriction, and that there is no evidence for ZIKV escape from this restriction in our system.

Influenza A virus undergoes compartmentalized replication in vivo dominated by stochastic bottlenecks.

Transmission of influenza A viruses (IAV) between hosts is subject to numerous physical and biological barriers that impose genetic bottlenecks, constraining viral diversity and adaptation. The bottlenecks within hosts and their potential impacts on evolutionary pathways taken during infection are poorly understood. To address this, we created highly diverse IAV libraries bearing molecular barcodes on two gene segments, enabling high-resolution tracking and quantification of unique virus lineages within hosts. Here we show that IAV infection in lungs is characterized by multiple within-host bottlenecks that result in "islands" of infection in lung lobes, each with genetically distinct populations. We perform site-specific inoculation of barcoded IAV in the upper respiratory tract of ferrets and track viral diversity as infection spreads to the trachea and lungs. We detect extensive compartmentalization of discrete populations within lung lobes. Bottleneck events and localized replication stochastically sample individual viruses from the upper respiratory tract or the trachea that become the dominant genotype in a particular lobe. These populations are shaped strongly by founder effects, with limited evidence for positive selection. The segregated sites of replication highlight the jackpot-style events that contribute to within-host influenza virus evolution and may account for low rates of intrahost adaptation.

SARS-CoV-2 and other respiratory pathogens are detected in continuous air samples from congregate settings.

Two years after the emergence of SARS-CoV-2, there is still a need for better ways to assess the risk of transmission in congregate spaces. We deployed active air samplers to monitor the presence of SARS-CoV-2 in real-world settings across communities in the Upper Midwestern states of Wisconsin and Minnesota. Over 29 weeks, we collected 527 air samples from 15 congregate settings and detected 106 SARS-CoV-2 positive samples, demonstrating SARS-CoV-2 can be detected in air collected from daily and weekly sampling intervals. We expanded the utility of air surveillance to test for 40 other respiratory pathogens. Surveillance data revealed differences in timing and location of SARS-CoV-2 and influenza A virus detection in the community. In addition, we obtained SARS-CoV-2 genome sequences from air samples to identify variant lineages. Collectively, this shows air surveillance is a scalable, cost-effective, and high throughput alternative to individual testing for detecting respiratory pathogens in congregate settings.

SARS-CoV-2 and other respiratory pathogens are detected in continuous air samples from congregate settings.

Two years after the emergence of SARS-CoV-2, there is still a need for better ways to assess the risk of transmission in congregate spaces. We deployed active air samplers to monitor the presence of SARS-CoV-2 in real-world settings across communities in the Upper Midwestern states of Wisconsin and Minnesota. Over 29 weeks, we collected 527 air samples from 15 congregate settings. We detected 106 samples that were positive for SARS-CoV-2 viral RNA, demonstrating that SARS-CoV-2 can be detected in continuous air samples collected from a variety of real-world settings. We expanded the utility of air surveillance to test for 40 other respiratory pathogens. Surveillance data revealed differences in timing and location of SARS-CoV-2 and influenza A virus detection. In addition, we obtained SARS-CoV-2 genome sequences from air samples to identify variant lineages. Collectively, this shows air sampling is a scalable, high throughput surveillance tool that could be used in conjunction with other methods for detecting respiratory pathogens in congregate settings.

Estimating the capacity of Chamaecrista fasciculata for adaptation to change in precipitation.

Adaptation through natural selection may be the only means by which small and fragmented plant populations will persist through present day environmental change. A population's additive genetic variance for fitness (VA (W)) represents its immediate capacity to adapt to the environment in which it exists. We evaluated this property for a population of the annual legume Chamaecrista fasciculata through a quantitative genetic experiment in the tallgrass prairie region of the Midwestern United States, where changing climate is predicted to include more variability in rainfall. To reduce incident rainfall, relative to controls receiving ambient rain, we deployed rain exclusion shelters. We found significant VA (W) in both treatments. We also detected a significant genotype-by-treatment interaction for fitness, which suggests that the genetic basis of the response to natural selection will differ depending on precipitation. For the trait-specific leaf area, we detected maladaptive phenotypic plasticity and an interaction between genotype and environment. Selection for thicker leaves was detected with increased precipitation. These results indicate capacity of this population of C. fasciculata to adapt in situ to environmental change.

Transmission of SARS-CoV-2 in domestic cats imposes a narrow bottleneck.

The evolutionary mechanisms by which SARS-CoV-2 viruses adapt to mammalian hosts and, potentially, undergo antigenic evolution depend on the ways genetic variation is generated and selected within and between individual hosts. Using domestic cats as a model, we show that SARS-CoV-2 consensus sequences remain largely unchanged over time within hosts, while dynamic sub-consensus diversity reveals processes of genetic drift and weak purifying selection. We further identify a notable variant at amino acid position 655 in Spike (H655Y), which was previously shown to confer escape from human monoclonal antibodies. This variant arises rapidly and persists at intermediate frequencies in index cats. It also becomes fixed following transmission in two of three pairs. These dynamics suggest this site may be under positive selection in this system and illustrate how a variant can quickly arise and become fixed in parallel across multiple transmission pairs. Transmission of SARS-CoV-2 in cats involved a narrow bottleneck, with new infections founded by fewer than ten viruses. In RNA virus evolution, stochastic processes like narrow transmission bottlenecks and genetic drift typically act to constrain the overall pace of adaptive evolution. Our data suggest that here, positive selection in index cats followed by a narrow transmission bottleneck may have instead accelerated the fixation of S H655Y, a potentially beneficial SARS-CoV-2 variant. Overall, our study suggests species- and context-specific adaptations are likely to continue to emerge. This underscores the importance of continued genomic surveillance for new SARS-CoV-2 variants as well as heightened scrutiny for signatures of SARS-CoV-2 positive selection in humans and mammalian model systems.

Methylation of all BRCA1 copies predicts response to the PARP inhibitor rucaparib in ovarian carcinoma.

Accurately identifying patients with high-grade serous ovarian carcinoma (HGSOC) who respond to poly(ADP-ribose) polymerase inhibitor (PARPi) therapy is of great clinical importance. Here we show that quantitative BRCA1 methylation analysis provides new insight into PARPi response in preclinical models and ovarian cancer patients. The response of 12 HGSOC patient-derived xenografts (PDX) to the PARPi rucaparib was assessed, with variable dose-dependent responses observed in chemo-naive BRCA1/2-mutated PDX, and no responses in PDX lacking DNA repair pathway defects. Among BRCA1-methylated PDX, silencing of all BRCA1 copies predicts rucaparib response, whilst heterozygous methylation is associated with resistance. Analysis of 21 BRCA1-methylated platinum-sensitive recurrent HGSOC (ARIEL2 Part 1 trial) confirmed that homozygous or hemizygous BRCA1 methylation predicts rucaparib clinical response, and that methylation loss can occur after exposure to chemotherapy. Accordingly, quantitative BRCA1 methylation analysis in a pre-treatment biopsy could allow identification of patients most likely to benefit, and facilitate tailoring of PARPi therapy.

Molecular correlates of platinum response in human high-grade serous ovarian cancer patient-derived xenografts.

INTRODUCTION: Improvement in the ability to target underlying drivers and vulnerabilities of high-grade serous ovarian cancer (HG-SOC) requires the development of molecularly annotated pre-clinical models reflective of clinical responses. METHODS: We generated patient-derived xenografts (PDXs) from consecutive, chemotherapy-naïve, human HG-SOC by transplanting fresh human HG-SOC fragments into subcutaneous and intra-ovarian bursal sites of NOD/SCID IL2Rγ(null) recipient mice, completed molecular annotation and assessed platinum sensitivity. RESULTS: The success rate of xenografting was 83%. Of ten HG-SOC PDXs, all contained mutations in TP53, two were mutated for BRCA1, three for BRCA2, and in two, BRCA1 was methylated. In vivo cisplatin response, determined as platinum sensitive (progression-free interval ≥ 100 d, n = 4), resistant (progression-free interval <100 d, n = 3) or refractory (n = 3), was largely consistent with patient outcome. Three of four platinum sensitive HG-SOC PDXs contained DNA repair gene mutations, and the fourth was methylated for BRCA1. In contrast, all three platinum refractory PDXs overexpressed dominant oncogenes (CCNE1, LIN28B and/or BCL2). CONCLUSIONS: Because PDX platinum response reflected clinical outcome, these annotated PDXs will provide a unique model system for preclinical testing of novel therapies for HG-SOC.