Evolution of two distinct variable lymphocyte receptors in lampreys: VLRD and VLRE.

Jawless vertebrates possess an alternative adaptive immune system in which antigens are recognized by variable lymphocyte receptors (VLRs) generated by combinatorial assembly of leucine-rich repeat (LRR) cassettes. Three types of receptors, VLRA, VLRB, and VLRC, have been previously identified. VLRA- and VLRC-expressing cells are T cell-like, whereas VLRB-expressing cells are B cell-like. Here, we report two types of VLRs in lampreys, VLRD and VLRE, phylogenetically related to VLRA and VLRC. The germline VLRD and VLRE genes are flanked by 39 LRR cassettes used in the assembly of mature VLRD and VLRE, with cassettes from chromosomes containing the VLRA and VLRC genes also contributing to VLRD and VLRE assemblies. VLRD and VLRE transcription is highest in the triple-negative (VLRA-/VLRB-/VLRC-) population of lymphocytes, albeit also detectable in VLRA+ and VLRC+ populations. Tissue distribution studies suggest that lamprey VLRD+ and VLRE+ lymphocytes comprise T-like sublineages of cells.

Presynaptic Congenital Myasthenic Syndromes: Understanding Clinical Phenotypes through In vivo Models.

Presynaptic congenital myasthenic syndromes (CMS) are a group of genetic disorders affecting the presynaptic side of the neuromuscular junctions (NMJ). They can result from a dysfunction in acetylcholine (ACh) synthesis or recycling, in its packaging into synaptic vesicles, or its subsequent release into the synaptic cleft. Other proteins involved in presynaptic endplate development and maintenance can also be impaired.Presynaptic CMS usually presents during the prenatal or neonatal period, with a severe phenotype including congenital arthrogryposis, developmental delay, and apnoeic crisis. However, milder phenotypes with proximal muscle weakness and good response to treatment have been described. Finally, many presynaptic genes are expressed in the brain, justifying the presence of additional central nervous system symptoms.Several animal models have been developed to study CMS, providing the opportunity to identify disease mechanisms and test treatment options. In this review, we describe presynaptic CMS phenotypes with a focus on in vivo models, to better understand CMS pathophysiology and define new causative genes.

Analysis of financial challenges faced by graduate students in Canada.

Graduate students are vital to the creation of research and innovation in Canada. The National Graduate Student Finance Survey was launched in 2021 by the Ottawa Science Policy Network to investigate the financial realities of Canadian graduate students. Closing in April 2022, the survey received 1305 responses from graduate students representing various geographical locations, years of study, fields of education, and demographic backgrounds. The results capture a snapshot into graduate student finances, including an in-depth analysis of stipends, scholarships, debt, tuition, and living expenses. In its entirety, we found that the majority of graduate students are facing serious financial concerns. This is largely due to stagnant funding for students both from federal and provincial granting agencies and from within their institutions. This reality is even worse for international students, members of historically underrepresented communities, and those with dependents, all of whom experience additional challenges that impact their financial security. Based on our findings, we propose several recommendations to the Tri-Council agencies (Natural Sciences and Engineering Research Council, Social Science and Humanities Research Council, and Canadian Institute for Health Research) and academic institutions to strengthen graduate student finances and help sustain the future of research in Canada.

Inhibition of PANX1 Channels Reduces the Malignant Properties of Human High-Risk Neuroblastoma.

Pannexin 1 (PANX1) is expressed in many tissue types including tissues of neural origin. Neuroblastoma (NB) is a neural crest-derived malignancy mainly occurring in children. The majority of NB patients present with high-risk disease for which current therapies are ineffective. Here, we show that while PANX1 is expressed in NB of all stages, high PANX1 expression in high-risk NB is associated with a reduced survival probability. PANX1 channel inhibition using probenecid (PBN) or carbenoxolone (CBX) reduced the proliferation of our panel of high-risk NB cell lines. We show that expression of the Y10F PANX1 mutant, which cannot be phosphorylated on tyrosine 10 and acts in a dominant-negative manner, curtailed NB cell proliferation. Furthermore, PBN and CBX treatment halted the growth of NB spheroids and in some cases triggered the regression of established NB spheroids. Finally, both drugs reduced the progression of high-risk NB in vivo. Together our data indicate that PANX1 channels regulate human NB malignant properties and that the use of PBN or CBX may provide a new therapeutic approach for high-risk NB.

Why marginal CO2 emissions are not decreasing for US electricity: Estimates and implications for climate policy.

Marginal emissions of CO2 from the electricity sector are critical for evaluating climate policies that rely on shifts in electricity demand or supply. This paper provides estimates of marginal CO2 emissions from US electricity generation using the most recently available and comprehensive data. The estimates vary by region, hour of the day, and year to year over the last decade. We identify an important and somewhat counterintuitive finding: While average emissions have decreased substantially over the last decade (28% nationally), marginal emissions have increased (7% nationally). We show that underlying these trends is primarily a shift toward greater reliance on coal to satisfy marginal electricity use. We apply our estimates to an analysis of the Biden administration's target of having electric vehicles (EVs) make up 50% of new vehicle purchases by 2030. We find that, without significant and concurrent changes to the electricity sector, the increase in electricity emissions is likely to offset more than half of the emission reductions from having fewer gasoline-powered vehicles on the road. Moreover, using average rather than marginal emissions to predict the impacts significantly overestimates the emission benefits. Overall, we find that the promise of EVs for reducing emissions depends, to a large degree, on complementary policies that decarbonize both average and marginal emissions in the electricity sector.

Trust and The Acquisition and Use of Public Health Information.

Information is clearly vital to public health, but the acquisition and use of public health data elicit serious privacy concerns. One strategy for navigating this dilemma is to build 'trust' in institutions responsible for health information, thereby reducing privacy concerns and increasing willingness to contribute personal data. This strategy, as currently presented in public health literature, has serious shortcomings. But it can be augmented by appealing to the philosophical analysis of the concept of trust. Philosophers distinguish trust and trustworthiness from cognate attitudes, such as confident reliance. Central to this is value congruence: trust is grounded in the perception of shared values. So, the way to build trust in institutions responsible for health data is for those institutions to develop and display values shared by the public. We defend this approach from objections, such as that trust is an interpersonal attitude inappropriate to the way people relate to organisations. The paper then moves on to the practical application of our strategy. Trust and trustworthiness can reduce privacy concerns and increase willingness to share health data, notably, in the context of internal and external threats to data privacy. We end by appealing for the sort of empirical work our proposal requires.

Clinical predictors of nonadherence to positive airway pressure therapy in children: a retrospective cohort study.

STUDY OBJECTIVES: Despite the importance of treating sleep-disordered breathing, positive airway pressure adherence rates in children are low. Identifying readily available predictors of nonadherence would enable the development of targeted interventions and supports, but literature is limited. Our objective was to identify baseline clinical predictors of 6-month positive airway pressure therapy nonadherence in children with SDB through a retrospective cohort study. METHODS: This study evaluated children (ages 8-17 years) prescribed positive airway pressure therapy for sleep-disordered breathing between 2011 and 2017 at a single pediatric tertiary hospital. The primary outcome was nonadherence at 6 months, measured using both machine downloads and self-report. Candidate baseline predictors included demographics, comorbidities, and sleep-disordered breathing characteristics. Relative risks (RR) and 95% confidence intervals (CI) were estimated using a modified Poisson regression. Missing data were imputed prior to analysis. RESULTS: The study included 104 children. The independent predictors most strongly associated with greater nonadherence were older age (RR = 1.08 for a 1-year increase; 95% CI, 1.00-1.16) and higher oxygen saturation nadir (RR = 1.03 for a 1% increase; 95% CI, 1.00-1.05), whereas those most strongly associated with lower nonadherence were higher arousal index (RR = 0.97 for a 1 event/h increase; 95% CI, 0.95-1.00), developmental delay (RR = 0.58; 95% CI, 0.30-1.13), and asthma (RR = 0.72; 95% CI, 0.44-1.17). CONCLUSIONS: Overall, children who are older, have less-severe sleep-disordered breathing, or less-disrupted sleep at baseline are more likely to be nonadherent to positive airway pressure therapy and may benefit from additional supports to acclimatize to therapy. As clinical predictors were only weakly associated with nonadherence, nonclinical characteristics may play a larger role in predicting adherence.

The immunogenetics of sexual parasitism.

Sexual parasitism has evolved as a distinctive mode of reproduction among deep-sea anglerfishes. The permanent attachment of males to host females observed in these species represents a form of anatomical joining, which is otherwise unknown in nature. Pronounced modifications to immune facilities are associated with this reproductive trait. The genomes of species with temporarily attaching males lack functional aicda genes that underpin affinity maturation of antibodies. Permanent attachment is associated with additional alterations, culminating in the loss of functional rag genes in some species, abolishing somatic diversification of antigen receptor genes, the hallmark of canonical adaptive immunity. In anglerfishes, coevolution of innate and adaptive immunity has been disentangled, implying that an alternative form of immunity supported the emergence of this evolutionarily successful group of vertebrates.

Cytidine deaminase 2 is required for VLRB antibody gene assembly in lampreys.

The antibodies of jawless vertebrates consist of leucine-rich repeat arrays encoded by somatically assembled VLRB genes. It is unknown how the incomplete germline VLRB loci are converted into functional antibody genes during B lymphocyte development in lampreys. In Lampetra planeri larvae lacking the cytidine deaminase CDA2 gene, VLRB assembly fails, whereas the T lineage-associated VLRA and VLRC antigen receptor gene assemblies occur normally. Thus, CDA2 acts in a B cell lineage-specific fashion to support the somatic diversification of VLRB antibody genes. CDA2 is closely related to activation-induced cytidine deaminase (AID), which is essential for the elaboration of immunoglobulin gene repertoires in jawed vertebrates. Our results thus identify a convergent mechanism of antigen receptor gene assembly and diversification that independently evolved in the two sister branches of vertebrates.

IL-21/type I interferon interplay regulates neutrophil-dependent innate immune responses to Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major hospital- and community-acquired pathogen, but the mechanisms underlying host-defense to MRSA remain poorly understood. Here, we investigated the role of IL-21 in this process. When administered intra-tracheally into wild-type mice, IL-21 induced granzymes and augmented clearance of pulmonary MRSA but not when neutrophils were depleted or a granzyme B inhibitor was added. Correspondingly, IL-21 induced MRSA killing by human peripheral blood neutrophils. Unexpectedly, however, basal MRSA clearance was also enhanced when IL-21 signaling was blocked, both in Il21r KO mice and in wild-type mice injected with IL-21R-Fc fusion-protein. This correlated with increased type I interferon and an IFN-related gene signature, and indeed anti-IFNAR1 treatment diminished MRSA clearance in these animals. Moreover, we found that IFNß induced granzyme B and promoted MRSA clearance in a granzyme B-dependent fashion. These results reveal an interplay between IL-21 and type I IFN in the innate immune response to MRSA.

Stages of life: A new metaphysics of conceptionism.

When a human being comes into existence is crucial in bioethics. Conceptionism is the view that a human being comes into existence at conception. The twinning argument is an influential objection to this view. All versions of the twinning argument rely on a metaphysics of material objects, namely, endurantism. Given this, a strategy for defending conceptionism against the twinning argument is to deny endurantism and adopt an alternative metaphysics of material objects. A version of this strategy which has been debated in this journal is to adopt perdurantism, or the 'multiple occupancy view', on which monozygotic twins share the zygote region as a temporal part. We present a novel version of this strategy: conceptionists can evade the twinning argument by adopting an exdurantist metaphysics of material objects. We suggest reasons for thinking that this is a plausible and, indeed, preferable way for conceptionists to avoid the twinning argument.

IGG4-RELATED OPHTHALMIC DISEASE PRESENTING AS CHOROIDAL AND ORBITAL LESIONS.

PURPOSE: To report a case of IgG4-related ophthalmic disease (IgG4-ROD) which presented as choroidal and orbital lesions. METHODS: Case report. RESULTS: A 64-year-old man presented with left eye photopsias and a history of IgG4-related perirenal fibrosis. Fundoscopic examination showed multiple bilateral yellow choroidal lesions, and optical coherence tomography showed multiple choroidal lesions. Magnetic resonance imaging of the orbits showed an enhancing lesion present circumferential to the optic nerve, but greater medially, abutting the posterior surface of the left globe. Workup for infectious, autoimmune, and malignant etiologies was negative, and the patient has responded well to treatment with rituximab. CONCLUSION: IgG4-related disease is a systemic fibroinflammatory disease, which often presents in another location, as in our patient. In cases of uncertain choroidal and orbital lesions, a thorough workup for other etiologies is indicated, and lymphoma must be ruled out. Steroids are the mainstay of treatment for IgG4-ROD, however, small case series and our patient responded well to rituximab. To our knowledge, this is the first reported case of choroidal and orbital lesions secondary to IgG4-ROD.

Diversification of AID/APOBEC-like deaminases in metazoa: multiplicity of clades and widespread roles in immunity.

AID/APOBEC deaminases (AADs) convert cytidine to uridine in single-stranded nucleic acids. They are involved in numerous mutagenic processes, including those underpinning vertebrate innate and adaptive immunity. Using a multipronged sequence analysis strategy, we uncover several AADs across metazoa, dictyosteliida, and algae, including multiple previously unreported vertebrate clades, and versions from urochordates, nematodes, echinoderms, arthropods, lophotrochozoans, cnidarians, and porifera. Evolutionary analysis suggests a fundamental division of AADs early in metazoan evolution into secreted deaminases (SNADs) and classical AADs, followed by diversification into several clades driven by rapid-sequence evolution, gene loss, lineage-specific expansions, and lateral transfer to various algae. Most vertebrate AADs, including AID and APOBECs1-3, diversified in the vertebrates, whereas the APOBEC4-like clade has a deeper origin in metazoa. Positional entropy analysis suggests that several AAD clades are diversifying rapidly, especially in the positions predicted to interact with the nucleic acid target motif, and with potential viral inhibitors. Further, several AADs have evolved neomorphic metal-binding inserts, especially within loops predicted to interact with the target nucleic acid. We also observe polymorphisms, driven by alternative splicing, gene loss, and possibly intergenic recombination between paralogs. We propose that biological conflicts of AADs with viruses and genomic retroelements are drivers of rapid AAD evolution, suggesting a widespread presence of mutagenesis-based immune-defense systems. Deaminases like AID represent versions "institutionalized" from the broader array of AADs pitted in such arms races for mutagenesis of self-DNA, and similar recruitment might have independently occurred elsewhere in metazoa.

Expansions, diversification, and interindividual copy number variations of AID/APOBEC family cytidine deaminase genes in lampreys.

Cytidine deaminases of the AID/APOBEC family catalyze C-to-U nucleotide transitions in mRNA or DNA. Members of the APOBEC3 branch are involved in antiviral defense, whereas AID contributes to diversification of antibody repertoires in jawed vertebrates via somatic hypermutation, gene conversion, and class switch recombination. In the extant jawless vertebrate, the lamprey, two members of the AID/APOBEC family are implicated in the generation of somatic diversity of the variable lymphocyte receptors (VLRs). Expression studies linked CDA1 and CDA2 genes to the assembly of VLRA/C genes in T-like cells and the VLRB genes in B-like cells, respectively. Here, we identify and characterize several CDA1-like genes in the larvae of different lamprey species and demonstrate that these encode active cytidine deaminases. Structural comparisons of the CDA1 variants highlighted substantial differences in surface charge; this observation is supported by our finding that the enzymes require different conditions and substrates for optimal activity in vitro. Strikingly, we also found that the number of CDA-like genes present in individuals of the same species is variable. Nevertheless, irrespective of the number of different CDA1-like genes present, all lamprey larvae have at least one functional CDA1-related gene encoding an enzyme with predicted structural and chemical features generally comparable to jawed vertebrate AID. Our findings suggest that, similar to APOBEC3 branch expansion in jawed vertebrates, the AID/APOBEC family has undergone substantial diversification in lamprey, possibly indicative of multiple distinct biological roles.

Evolution of Alternative Adaptive Immune Systems in Vertebrates.

Adaptive immunity in jawless fishes is based on antigen recognition by three types of variable lymphocyte receptors (VLRs) composed of variable leucine-rich repeats, which are differentially expressed by two T-like lymphocyte lineages and one B-like lymphocyte lineage. The T-like cells express either VLRAs or VLRCs of yet undefined antigen specificity, whereas the VLRB antibodies secreted by B-like cells bind proteinaceous and carbohydrate antigens. The incomplete VLR germline genes are assembled into functional units by a gene conversion-like mechanism that employs flanking variable leucine-rich repeat sequences as templates in association with lineage-specific expression of cytidine deaminases. B-like cells develop in the hematopoietic typhlosole and kidneys, whereas T-like cells develop in the thymoid, a thymus-equivalent region at the gill fold tips. Thus, the dichotomy between T-like and B-like cells and the presence of dedicated lymphopoietic tissues emerge as ancestral vertebrate features, whereas the somatic diversification of structurally distinct antigen receptor genes evolved independently in jawless and jawed vertebrates.

Direct detection of neural activity in vitro using magnetic resonance electrical impedance tomography (MREIT).

We describe a sequence of experiments performed in vitro to verify the existence of a new magnetic resonance imaging contrast - Magnetic Resonance Electrical Impedance Tomography (MREIT) -sensitive to changes in active membrane conductivity. We compared standard deviations in MREIT phase data from spontaneously active Aplysia abdominal ganglia in an artificial seawater background solution (ASW) with those found after treatment with an excitotoxic solution (KCl). We found significant increases in MREIT treatment cases, compared to control ganglia subject to extra ASW. This distinction was not found in phase images from the same ganglia using no imaging current. Further, significance and effect size depended on the amplitude of MREIT imaging current used. We conclude that our observations were linked to changes in cell conductivity caused by activity. Functional MREIT may have promise as a more direct method of functional neuroimaging than existing methods that image correlates of blood flow such as BOLD fMRI.

Trust and Its Role in the Medical Encounter.

This paper addresses two research questions. The first is theoretical: What is trust? In the first half of this paper we present a distinctive tripartite analysis. We describe three attitudes, here called reliance, specific trust and general trust, each of which is characterised and illustrated. We argue that these attitudes are related, but not reducible, to one another. We suggest that the current impasse in the analysis of trust is in part due to the fact that some writers allude to these distinctions, but unclearly so, whilst others elide them altogether. The second research question focuses on doctor-patient interaction. Trust is often said to be central in medical encounters but this strikes us as too vague. The success of doctor-patient relations in part depends on adopting the most appropriate of the three attitudes we delineate. We argue that reliance is the appropriate attitude for most medical encounters. When circumstances do require trust, the distinction between specific trust and general trust is crucial. We describe medical encounters requiring specific trust. General trust is less often required in medicine; but it is appropriate in some cases and, when called for, it is called for strongly.