Lineage tracing reveals B cell antibody class switching is stochastic, cell-autonomous, and tuneable.

To optimize immunity to pathogens, B lymphocytes generate plasma cells with functionally diverse antibody isotypes. By lineage tracing single cells within differentiating B cell clones, we identified the heritability of discrete fate controlling mechanisms to inform a general mathematical model of B cell fate regulation. Founder cells highly influenced clonal plasma-cell fate, whereas class switch recombination (CSR) was variegated within clones. In turn, these CSR patterns resulted from independent all-or-none expression of both activation-induced cytidine deaminase (AID) and IgH germline transcription (GLT), with the latter being randomly re-expressed after each cell division. A stochastic model premised on these molecular transition rules accurately predicted antibody switching outcomes under varied conditions in vitro and during an immune response in vivo. Thus, the generation of functionally diverse antibody types follows rules of autonomous cellular programming that can be adapted and modeled for the rational control of antibody classes for potential therapeutic benefit.

Pomalidomide for Epistaxis in Hereditary Hemorrhagic Telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is characterized by extensive telangiectasias and arteriovenous malformations. The primary clinical manifestation is epistaxis that results in iron-deficiency anemia and reduced health-related quality of life. METHODS: We conducted a randomized, placebo-controlled trial to evaluate the safety and efficacy of pomalidomide for the treatment of HHT. We randomly assigned patients, in a 2:1 ratio, to receive pomalidomide at a dose of 4 mg daily or matching placebo for 24 weeks. The primary outcome was the change from baseline through week 24 in the Epistaxis Severity Score (a validated bleeding score in HHT; range, 0 to 10, with higher scores indicating worse bleeding). A reduction of 0.71 points or more is considered clinically significant. A key secondary outcome was the HHT-specific quality-of-life score (range, 0 to 16, with higher scores indicating more limitations). RESULTS: The trial was closed to enrollment in June 2023 after a planned interim analysis met a prespecified threshold for efficacy. A total of 144 patients underwent randomization; 95 patients were assigned to receive pomalidomide and 49 to receive placebo. The baseline mean (±SD) Epistaxis Severity Score was 5.0±1.5, a finding consistent with moderate-to-severe epistaxis. At 24 weeks, the mean difference between the pomalidomide group and the placebo group in the change from baseline in the Epistaxis Severity Score was -0.94 points (95% confidence interval [CI], -1.57 to -0.31; P = 0.004). The mean difference in the changes in the HHT-specific quality-of-life score between the groups was -1.4 points (95% CI, -2.6 to -0.3). Adverse events that were more common in the pomalidomide group than in the placebo group included neutropenia, constipation, and rash. CONCLUSIONS: Among patients with HHT, pomalidomide treatment resulted in a significant, clinically relevant reduction in epistaxis severity. No unexpected safety signals were identified. (Funded by the National Heart, Lung, and Blood Institute; PATH-HHT Clinicaltrials.gov number, NCT03910244).

Opposing roles for Egalitarian and Staufen in transport, anchoring and localization of oskar mRNA in the Drosophila oocyte.

Localization of oskar mRNA includes two distinct phases: transport from nurse cells to the oocyte, a process typically accompanied by cortical anchoring in the oocyte, followed by posterior localization within the oocyte. Signals within the oskar 3' UTR directing transport are individually weak, a feature previously hypothesized to facilitate exchange between the different localization machineries. We show that alteration of the SL2a stem-loop structure containing the oskar transport and anchoring signal (TAS) removes an inhibitory effect such that in vitro binding by the RNA transport factor, Egalitarian, is elevated as is in vivo transport from the nurse cells into the oocyte. Cortical anchoring within the oocyte is also enhanced, interfering with posterior localization. We also show that mutation of Staufen recognized structures (SRSs), predicted binding sites for Staufen, disrupts posterior localization of oskar mRNA just as in staufen mutants. Two SRSs in SL2a, one overlapping the Egalitarian binding site, are inferred to mediate Staufen-dependent inhibition of TAS anchoring activity, thereby promoting posterior localization. The other three SRSs in the oskar 3' UTR are also required for posterior localization, including two located distant from any known transport signal. Staufen, thus, plays multiple roles in localization of oskar mRNA.

Hexavalent sperm-binding IgG antibody released from vaginal film for development of potent on-demand nonhormonal female contraception.

Nonhormonal products for on-demand contraception are a global health technology gap; this unmet need motivated us to pursue the use of sperm-binding monoclonal antibodies to enable effective on-demand contraception. Here, using the cGMP-compliant Nicotiana-expression system, we produced an ultrapotent sperm-binding IgG antibody possessing 6 Fab arms per molecule that bind a well-established contraceptive antigen target, CD52g. We term this hexavalent antibody "Fab-IgG-Fab" (FIF). The Nicotiana-produced FIF had at least 10-fold greater sperm-agglutination potency and kinetics than the parent IgG, while preserving Fc-mediated trapping of individual spermatozoa in mucus. We formulated the Nicotiana-produced FIF into a polyvinyl alcohol-based water-soluble contraceptive film and evaluated its potency in reducing progressively motile sperm in the sheep vagina. Two minutes after vaginal instillation of human semen, no progressively motile sperm were recovered from the vaginas of sheep receiving FIF Film. Our work supports the potential of multivalent contraceptive antibodies to provide safe, effective, on-demand nonhormonal contraception.

Therapy for Argentine hemorrhagic fever in nonhuman primates with a humanized monoclonal antibody.

The COVID-19 pandemic has reemphasized the need to identify safe and scalable therapeutics to slow or reverse symptoms of disease caused by newly emerging and reemerging viral pathogens. Recent clinical successes of monoclonal antibodies (mAbs) in therapy for viral infections demonstrate that mAbs offer a solution for these emerging biothreats. We have explored this with respect to Junin virus (JUNV), an arenavirus classified as a category A high-priority agent and the causative agent of Argentine hemorrhagic fever (AHF). There are currently no Food and Drug Administration-approved drugs available for preventing or treating AHF, although immune plasma from convalescent patients is used routinely to treat active infections. However, immune plasma is severely limited in quantity, highly variable in quality, and poses significant safety risks including the transmission of transfusion-borne diseases. mAbs offer a highly specific and consistently potent alternative to immune plasma that can be manufactured at large scale. We previously described a chimeric mAb, cJ199, that provided protection in a guinea pig model of AHF. To adapt this mAb to a format more suitable for clinical use, we humanized the mAb (hu199) and evaluated it in a cynomolgus monkey model of AHF with two JUNV isolates, Romero and Espindola. While untreated control animals experienced 100% lethality, all animals treated with hu199 at 6 d postinoculation (dpi) survived, and 50% of animals treated at 8 dpi survived. mAbs like hu199 may offer a safer, scalable, and more reproducible alternative to immune plasma for rare viral diseases that have epidemic potential.

Different roles for the adjoining and structurally similar A-rich and poly(A) domains of oskar mRNA: Only the A-rich domain is required for oskar noncoding RNA function, which includes MTOC positioning.

Drosophila oskar (osk) mRNA has both coding and noncoding functions, with the latter required for progression through oogenesis. Noncoding activity is mediated by the osk 3' UTR. Three types of cis elements act most directly and are clustered within the final ~120 nucleotides of the 3' UTR: multiple binding sites for the Bru1 protein, a short highly conserved region, and A-rich sequences abutting the poly(A) tail. Here we extend the characterization of these elements and their functions, providing new insights into osk noncoding RNA function and the makeup of the cis elements. We show that all three elements are required for correct positioning of the microtubule organizing center (MTOC), a defect not previously reported for any osk mutant. Normally, the MTOC is located at the posterior of the oocyte during previtellogenic stages of oogenesis, and this distribution underlies the strong posterior enrichment of many mRNAs transported into the oocyte from the nurse cells. When osk noncoding function was disrupted the MTOC was dispersed in the oocyte and osk mRNA failed to be enriched at the posterior, although transport to the oocyte was not affected. A previous study did not detect loss of posterior enrichment for certain osk mutants lacking noncoding activity (Kanke et al., 2015). This discrepancy may be due to use of imaging aimed at monitoring transport to the oocyte rather than posterior enrichment. Involvement in MTOC positioning suggests that the osk noncoding function may act in conjunction with genes whose loss has similar effects, and that osk function may extend to other processes requiring those genes. Further characterization of the cis elements required for osk noncoding function included completion of saturation mutagenesis of the most highly conserved region, providing critical information for evaluating the possible contribution of candidate binding factors. The 3'-most cis element is a cluster of A-rich sequences, the ARS. The close juxtaposition and structural similarity of the ARS and poly(A) tail raised the possibility that they comprise an extended A-rich element required for osk noncoding function. We found that absence of the poly(A) tail did not mimic the effects of mutation of the ARS, causing neither arrest of oogenesis nor mispositioning of osk mRNA in previtellogenic stage oocytes. Thus, the ARS and the poly(A) tail are not interchangeable for osk noncoding RNA function, suggesting that the role of the ARS is not in recruitment of Poly(A) binding protein (PABP), the protein that binds the poly(A) tail. Furthermore, although PABP has been implicated in transport of osk mRNA from the nurse cells to the oocyte, mutation of the ARS in combination with loss of the poly(A) tail did not disrupt transport of osk mRNA into the oocyte. We conclude that PABP acts indirectly in osk mRNA transport, or is associated with osk mRNA independent of an A-rich binding site. Although the poly(A) tail was not required for osk mRNA transport into the oocyte, its absence was associated with a novel osk mRNA localization defect later in oogenesis, potentially revealing a previously unrecognized step in the localization process.

Synergy in IR-Hybrid CT/C-arm in the setting of critical trauma.

Access to multi-detector computed tomography (MDCT) scanning for interventional procedures can prove to be logistically challenging as resources are often in different areas within the hospital. At some institutions, interventional radiology suites have moved to the operating room, separate from the diagnostic radiology department. At these institutions, complex interventional procedures requiring both fluoroscopy and MDCT may pose logistical challenges, especially as they pertain to timely patient transfers. Hybrid CT/fluoroscopy suite provides rapid, reliable MDCT assessment of trauma patients before and after emergent surgery, as well as access to the entire spectrum of emergent image-guided interventions in the same suite.

Hereditary Hemorrhagic Telangiectasia: The Convergence of Genotype, Phenotype, and Imaging in Modern Diagnosis and Management of a Multisystem Disease.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disease that manifests as vascular malformations in the brain, lung, liver, gastrointestinal tract, nasal mucosa, and skin. Diagnosis and management of HHT is guided in large part by imaging studies, making it a condition with which the radiology community needs familiarity. Proper screening and care lead to improved morbidity and mortality in patients with HHT. International guidelines were recently updated and form the basis for a detailed discussion of the role of imaging and image-guided therapy in HHT. © RSNA, 2021 Online supplemental material is available for this article.

Speculations on the evolution of humoral adaptive immunity.

The protection of a multicellular organism from infection, at both cell and humoral levels, has been a tremendous driver of gene selection and cellular response strategies. Here we focus on a critical event in the development of humoral immunity: The transition from principally innate responses to a system of adaptive cell selection, with all the attendant mechanical problems that must be solved in order for it to work effectively. Here we review recent advances, but our major goal is to highlight that the development of adaptive immunity resulted from the adoption, reuse and repurposing of an ancient, autonomous cellular program that combines and exploits three titratable cellular fate timers. We illustrate how this common cell machinery recurs and appears throughout biology, and has been essential for the evolution of complex organisms, at many levels of scale.

Multiplexed Division Tracking Dyes for Proliferation-Based Clonal Lineage Tracing.

The generation of cellular heterogeneity is an essential feature of immune responses. Understanding the heritability and asymmetry of phenotypic changes throughout this process requires determination of clonal-level contributions to fate selection. Evaluating intraclonal and interclonal heterogeneity and the influence of distinct fate determinants in large numbers of cell lineages, however, is usually laborious, requiring familial tracing and fate mapping. In this study, we introduce a novel, accessible, high-throughput method for measuring familial fate changes with accompanying statistical tools for testing hypotheses. The method combines multiplexing of division tracking dyes with detection of phenotypic markers to reveal clonal lineage properties. We illustrate the method by studying in vitro-activated mouse CD8+ T cell cultures, reporting division and phenotypic changes at the level of families. This approach has broad utility as it is flexible and adaptable to many cell types and to modifications of in vitro, and potentially in vivo, fate monitoring systems.

Barriers and facilitators to retaining a cohort of street-based cisgender female sex workers recruited in Baltimore, Maryland, USA: results from the SAPPHIRE study.

BACKGROUND: Despite experiencing HIV/STIs, violence, and other morbidities at higher rates than the general public, street-based female sex workers are often absent from public health research and surveillance due to the difficulty and high costs associated with engagement and retention. The current study builds on existing literature by examining barriers and facilitators of retaining a street-based cohort of cisgender female sex workers recruited in a mobile setting in Baltimore, Maryland who participated in the SAPPHIRE study. Participants completed interviews and sexual health testing at baseline, 3-, 6-, 9-, and 12-months. METHODS: Retention strategies are described and discussed in light of their benefits and challenges. Strategies included collecting several forms of participant contact information, maintaining an extensive field presence by data collectors, conducting social media outreach and public record searches, and providing cash and non-cash incentives. We also calculated raw and adjusted retention proportions at each follow-up period. Lastly, baseline sample characteristics were compared by number of completed visits across demographic, structural vulnerabilities, work environment, and substance use variables using F-tests and Pearson's chi-square tests. RESULTS: Although there were drawbacks to each retention strategy, each method was useful in tandem in achieving a successful follow-up rate. While direct forms of contact such as phone calls, social media outreach, and email were useful for retaining more stable participants, less stable participants required extensive field-based efforts such as home and site visits that increase the likelihood of random encounters. Overall, adjusted retention exceeded 70% for the duration of the 12-month study. Participants who were younger, recently experienced homelessness, and injected drugs daily were less likely to have completed all or most follow-up visits. CONCLUSION: Retention of street-based female sex workers required the simultaneous use of diverse retention strategies that were tailored to participant characteristics. With familiarity of the dynamic nature of the study population characteristics, resources can be appropriately allocated to strategies most likely to result in successful retention.

Rapid, climate-driven changes in outlet glaciers on the Pacific coast of East Antarctica.

Observations of ocean-terminating outlet glaciers in Greenland and West Antarctica indicate that their contribution to sea level is accelerating as a result of increased velocity, thinning and retreat. Thinning has also been reported along the margin of the much larger East Antarctic ice sheet, but whether glaciers are advancing or retreating there is largely unknown, and there has been no attempt to place such changes in the context of localized mass loss or climatic or oceanic forcing. Here we present multidecadal trends in the terminus position of 175 ocean-terminating outlet glaciers along 5,400 kilometres of the margin of the East Antarctic ice sheet, and reveal widespread and synchronous changes. Despite large fluctuations between glaciers--linked to their size--three epochal patterns emerged: 63 per cent of glaciers retreated from 1974 to 1990, 72 per cent advanced from 1990 to 2000, and 58 per cent advanced from 2000 to 2010. These trends were most pronounced along the warmer western South Pacific coast, whereas glaciers along the cooler Ross Sea coast experienced no significant changes. We find that glacier change along the Pacific coast is consistent with a rapid and coherent response to air temperature and sea-ice trends, linked through the dominant mode of atmospheric variability (the Southern Annular Mode). We conclude that parts of the world's largest ice sheet may be more vulnerable to external forcing than recognized previously.

Biological concepts in recurrent Plasmodium vivax malaria.

A curious aspect of the evolution of the hypnozoite theory of malarial relapse is its transmogrification from theory into 'fact', this being of historical, linguistic, scientific and sociological interest. As far as it goes, the hypnozoite explanation for relapse is almost certainly correct. I contend, however, that many of the genotypically homologous, non-reinfection, relapse-like Plasmodium vivax recurrences that researchers ascribe to hypnozoite activation are probably hypnozoite-independent. Indeed, some malariologists are starting to recognize that homologous P. vivax recurrences have most likely been overattributed to activation of hypnozoites. Hitherto identified, non-hypnozoite, possible plasmodial sources of recurrence that must be considered, besides circulating erythrocytic stages, include parasites in splenic dendritic cells, other cells in the spleen (in addition to infected erythrocytes there), bone marrow (importantly) and the skin. I argue that we need to take into account the possibility of a dual or multiple extra-vascular origin of P. vivax non-reinfection recurrences, not arbitrarily discount it. The existence of a P. vivax reservoir(s) is a topical subject and one of practical importance for malaria eradication. Pertinent drug-associated matters are also discussed, as is the dormancy-related significance of clues provided by blood-stage-induced malarial infection.

Multi-modal and short-range transmission loss in thin, ice-covered, near-shore Arctic waters.

In the past century, extensive research has been done regarding the sound propagation in Arctic ice sheets. The majority of this research has focused on low-frequency propagation over long distances. Due to changing climate conditions in these environments, experimentation is warranted to determine sound propagation characteristics in, through, and under first-year, thin ice sheets, in shallow water, over short distances. In April 2016 several experiments were conducted approximately 2 km off the coast of Barrow, Alaska on shore-fast, first-year ice, approximately 1 m thick. To determine the propagation characteristics of various sound sources, frequency response functions were measured between a source location and several receiver locations at various distances from 1 m to 1 km. The primary sources used for this experiment were, an underwater speaker with various tonal outputs, an instrumented impact hammer on the ice, and a propane cannon that produced an acoustic blast wave in air. The transmission loss (TL) characteristics of the multipath propagation (air, ice, water) are investigated and reported. Data indicate that TL in frequency bands between 125 and 2000 Hz varied from approximately 3-6 dB per doubling of distance which is consistent with geometrical spreading losses, cylindrical and spherical, respectively.

Percutaneous embolization of post traumatic splenic pseudoaneurysm.

Management of splenic pseudoaneurysms in hemodynamically stable patients has shifted toward nonoperative management, including watchful waiting and endovascular embolization. Standard of treatment does not include percutaneous embolization for splenic pseudoaneurysm repair. In this case report, we document a successful percutaneous embolization of a post traumatic splenic pseudoaneurysm with thrombin. Percutaneous embolization of splenic pseudoaneurysms can be considered a viable technique in patients who fail endovascular embolization or have lesions inaccessible to endovascular repair.

Geospatial analysis of household spread of Ebola virus in a quarantined village - Sierra Leone, 2014.

We performed a spatial-temporal analysis to assess household risk factors for Ebola virus disease (Ebola) in a remote, severely-affected village. We defined a household as a family's shared living space and a case-household as a household with at least one resident who became a suspect, probable, or confirmed Ebola case from 1 August 2014 to 10 October 2014. We used Geographic Information System (GIS) software to calculate inter-household distances, performed space-time cluster analyses, and developed Generalized Estimating Equations (GEE). Village X consisted of 64 households; 42% of households became case-households over the observation period. Two significant space-time clusters occurred among households in the village; temporal effects outweighed spatial effects. GEE demonstrated that the odds of becoming a case-household increased by 4·0% for each additional person per household (P < 0·02) and 2·6% per day (P < 0·07). An increasing number of persons per household, and to a lesser extent, the passage of time after onset of the outbreak were risk factors for household Ebola acquisition, emphasizing the importance of prompt public health interventions that prioritize the most populated households. Using GIS with GEE can reveal complex spatial-temporal risk factors, which can inform prioritization of response activities in future outbreaks.

Development and usability testing of a web-based self-management intervention for oral cancer survivors and their family caregivers.

Oral cancer (OC) survivors experience debilitating side effects that affect their quality of life (QOL) and that of their caregivers. This study aimed to develop and evaluate a dyadic, web-based intervention to improve survivor self-management and survivor/caregiver QOL. A qualitative needs assessment (semi-structured interviews) with 13 OC survivors and 12 caregivers was conducted to discern information and support needs as well as preferences regarding website features and tools. Results using Grounded Theory analysis showed that OC survivors and caregivers: (1) want and need practical advice about managing side effects; (2) want to reach out to other survivors/caregivers for information and support; and (3) have both overlapping and unique needs and preferences regarding website features. Usability testing (N = 6 survivors; 5 caregivers) uncovered problems with the intuitiveness, navigation and design of the website that were subsequently addressed. Users rated the website favourably on the dimensions of attractiveness, controllability, efficiency, intuitiveness and learnability, and gave it a total usability score of 80/100. Overall, this study demonstrates that OC survivors and caregivers are interested in using an online programme to improve QOL, and that providing tailored website content and features based on the person's role as survivor or caregiver is important in this population.

CT-detected traumatic small artery extremity injuries: surgery, embolize, or watch? A 10-year experience.

Advances in computed tomography (CT) angiography have increased the sensitivity and specificity of detecting small branch arterial injuries in the extremities of trauma patients. However, it is unclear whether these patients should undergo surgery, angioembolization, or conservative watchful waiting. We hypothesized that uncomplicated small arterial branch injuries can be managed successfully with watchful waiting. A 10-year retrospective review of extremity CT angiograms with search findings of arterial "active extravasation" or "pseudoaneurysm" was performed at a level 1 county trauma center. Subgroup analysis was performed on those with isolated extremity injury and those with concurrent injuries. A total of 31 patients had CT-detected active extravasation (84 %) or pseudoaneurysm (16 %), 71 % of which were isolated vascular injuries. Of the patients evaluated, 71 % (n = 22) were managed with watchful waiting, 19 % (n = 6) with angioembolization, and 10 % (n = 3) with surgery. Watchful waiting complications included progression to alternative treatment (n = 1) and blood transfusions (n = 2). Complications of surgery included the inability to find active bleeding (n = 1) and postoperative psychosis (n = 1). Complications of angioembolization were limited to a postprocedure blood transfusion (n = 1). Patients with isolated vascular injuries had an average length of stay of 2.9 days, with management averages of the following: 2.7 days with watchful waiting (n = 16), 3.3 days with angioembolization (n = 3), and 3.7 days with surgery (n = 3). CT angiography has greatly increased the reported incidence of traumatic arterial injury in the extremity. We propose that small branch arterial injuries in the extremities can be managed successfully with watchful waiting and do not often require immediate embolization.

Bartonella quintana Aortitis in a Man with AIDS, Diagnosed by Needle Biopsy and 16S rRNA Gene Amplification.

A man with newly diagnosed AIDS presented with months of back pain and fever. Computed tomography (CT) results demonstrated aortitis with periaortic tissue thickening. DNA amplification of biopsy tissue revealed Bartonella quintana, and Bartonella serologies were subsequently noted to be positive. The patient improved with prolonged doxycycline and rifabutin treatment. This case illustrates how molecular techniques are increasingly important in diagnosing Bartonella infections.