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In this paper, I discuss dual collective action problems in which a resource pool has simultaneous common pool and public good aspects in its usage, such as hunting (consumption) and conservation of wildlife. I then implement laboratory experiments to evaluate how spillovers between the two related uses of nature affect the consumption and conservation habits of stakeholders. The Nash predictions suggest that even the most selfish of profit-maximizing agents have an incentive to provide equally towards resource consumption and conservation when resource spillovers are present. Results from laboratory experiments are consistent with this hypothesis. As a policy intervention, I introduced and later revoked a common pool licensing policy based on U.S. hunting and fishing licensing. Under the same theoretical framework, removing a common pool licensing policy would increase welfare for all resource stakeholders. Contrary to this, experimental evidence indicates no overall change in welfare.

Norway rats (Rattus norvegicus) are globally distributed and concentrate in urban environments, where they live and feed in closer proximity to human populations than most other mammals. Despite the potential role of rats as reservoirs of zoonotic diseases, the microbial diversity present in urban rat populations remains unexplored. In this study, we used targeted molecular assays to detect known bacterial, viral, and protozoan human pathogens and unbiased high-throughput sequencing to identify novel viruses related to agents of human disease in commensal Norway rats in New York City. We found that these rats are infected with bacterial pathogens known to cause acute or mild gastroenteritis in people, including atypical enteropathogenic Escherichia coli, Clostridium difficile, and Salmonella enterica, as well as infectious agents that have been associated with undifferentiated febrile illnesses, including Bartonella spp., Streptobacillus moniliformis, Leptospira interrogans, and Seoul hantavirus. We also identified a wide range of known and novel viruses from groups that contain important human pathogens, including sapoviruses, cardioviruses, kobuviruses, parechoviruses, rotaviruses, and hepaciviruses. The two novel hepaciviruses discovered in this study replicate in the liver of Norway rats and may have utility in establishing a small animal model of human hepatitis C virus infection. The results of this study demonstrate the diversity of microbes carried by commensal rodent species and highlight the need for improved pathogen surveillance and disease monitoring in urban environments. Importance: The observation that most emerging infectious diseases of humans originate in animal reservoirs has led to wide-scale microbial surveillance and discovery programs in wildlife, particularly in the developing world. Strikingly, less attention has been focused on commensal animals like rats, despite their abundance in urban centers and close proximity to human populations. To begin to explore the zoonotic disease risk posed by urban rat populations, we trapped and surveyed Norway rats collected in New York City over a 1-year period. This analysis revealed a striking diversity of known pathogens and novel viruses in our study population, including multiple agents associated with acute gastroenteritis or febrile illnesses in people. Our findings indicate that urban rats are reservoirs for a vast diversity of microbes that may affect human health and indicate a need for increased surveillance and awareness of the disease risks associated with urban rodent infestation.

We aimed to determine the risk of postpartum infection and increased pain associated with use of condom-catheter uterine balloon tamponade (UBT) among women diagnosed with postpartum hemorrhage (PPH) in three low- and middle-income countries (LMICs). We also sought women's opinions on their overall experience of PPH care. This prospective cohort study compared women diagnosed with PPH who received and did not receive UBT (UBT group and no-UBT group, respectively) at 18 secondary level hospitals in Uganda, Egypt, and Senegal that participated in a stepped wedge, cluster-randomized trial assessing UBT introduction. Key outcomes were reported pain (on a scale 0-10) in the immediate postpartum period and receipt of antibiotics within four weeks postpartum (a proxy for postpartum infection). Outcomes related to satisfaction with care and aspects women liked most and least about PPH care were also reported. Among women diagnosed with PPH, 58 were in the UBT group and 2188 in the no-UBT group. Self-reported, post-discharge antibiotic use within four weeks postpartum was similar in the UBT (3/58, 5.6%) and no-UBT groups (100/2188, 4.6%, risk ratio = 1.22, 95% confidence interval [CI]: 0.45-3.35). A high postpartum pain score of 8-10 was more common among women in the UBT group (17/46, 37.0%) than in the no-UBT group (360/1805, 19.9%, relative risk ratio = 3.64, 95% CI:1.30-10.16). Most women were satisfied with their care (1935/2325, 83.2%). When asked what they liked least about care, the most common responses were that medications (580/1511, 38.4%) and medical supplies (503/1511, 33.3%) were unavailable. UBT did not increase the risk of postpartum infection among this population. Women who receive UBT may experience higher degrees of pain compared to women who do not receive UBT. Women's satisfaction with their care and stockouts of medications and other supplies deserve greater attention when introducing new technologies like UBT.

ProteoPlex optimizes buffer conditions for the isolation and purification of macromolecular complexes. The concurrent complex stabilization is beneficial for structure determination using X-ray crystallography or cryo-electron microscopy. Molecular machines or macromolecular complexes are supramolecular assemblies of biomolecules with a variety of functions. Structure determination of these complexes in a purified state is often tedious owing to their compositional complexity and the associated relative structural instability. To improve the stability of macromolecular complexes in vitro , we present a generic method that optimizes the stability, homogeneity and solubility of macromolecular complexes by sparse-matrix screening of their thermal unfolding behavior in the presence of various buffers and small molecules. The method includes the automated analysis of thermal unfolding curves based on a biophysical unfolding model for complexes. We found that under stabilizing conditions, even large multicomponent complexes reveal an almost ideal two-state unfolding behavior. We envisage an improved biochemical understanding of purified macromolecules as well as a substantial boost in successful macromolecular complex structure determination by both X-ray crystallography and cryo-electron microscopy.

Significance The anaphase-promoting complex/cyclosome (APC) is a multisubunit RING E3 ubiquitin (Ub) ligase that regulates mitosis, meiosis, and numerous facets of neurobiology by targeting key regulatory proteins for Ub-mediated degradation. Despite great importance, it remains unclear how APC, or most of the other 600 RING E3s in humans, targets Ub to lysines in disordered substrates. Here, we report the structural and molecular basis for substrate ubiquitination by APC and its partner E2, UBCH10. UBCH10 is recruited to APC, activated for ubiquitination, and positioned for substrate targeting through multisite interactions with the APC cullin–RING core. We propose that many RING E3–E2 assemblies work similarly, with multisite interactions establishing specificity, harnessing ubiquitination machineries to accelerate searching for target lysines, and facilitating regulation. For many E3 ligases, a mobile RING (Really Interesting New Gene) domain stimulates ubiquitin (Ub) transfer from a thioester-linked E2∼Ub intermediate to a lysine on a remotely bound disordered substrate. One such E3 is the gigantic, multisubunit 1.2-MDa anaphase-promoting complex/cyclosome (APC), which controls cell division by ubiquitinating cell cycle regulators to drive their timely degradation. Intrinsically disordered substrates are typically recruited via their KEN-box, D-box, and/or other motifs binding to APC and a coactivator such as CDH1. On the opposite side of the APC, the dynamic catalytic core contains the cullin-like subunit APC2 and its RING partner APC11, which collaborates with the E2 UBCH10 (UBE2C) to ubiquitinate substrates. However, how dynamic RING–E2∼Ub catalytic modules such as APC11–UBCH10∼Ub collide with distally tethered disordered substrates remains poorly understood. We report structural mechanisms of UBCH10 recruitment to APC Cᴰᴴ¹ and substrate ubiquitination. Unexpectedly, in addition to binding APC11’s RING, UBCH10 is corecruited via interactions with APC2, which we visualized in a trapped complex representing an APC Cᴰᴴ¹–UBCH10∼Ub–substrate intermediate by cryo-electron microscopy, and in isolation by X-ray crystallography. To our knowledge, this is the first structural view of APC, or any cullin–RING E3, with E2 and substrate juxtaposed, and it reveals how tripartite cullin–RING–E2 interactions establish APC’s specificity for UBCH10 and harness a flexible catalytic module to drive ubiquitination of lysines within an accessible zone. We propose that multisite interactions reduce the degrees of freedom available to dynamic RING E3–E2∼Ub catalytic modules, condense the search radius for target lysines, increase the chance of active-site collision with conformationally fluctuating substrates, and enable regulation.

In malignant glioma, cytotoxic drugs are often inhibited from accessing the tumor site due to the blood-tumor barrier (BTB). Ibrutinib, FDA-approved lymphoma agent, inhibits Bruton tyrosine kinase (BTK) and has previously been shown to independently impair aortic endothelial adhesion and increase rodent glioma model survival in combination with cytotoxic therapy. Yet additional research is required to understand ibrutinib’s effect on BTB function. In this study, we detail baseline BTK expression in glioma cells and its surrounding vasculature, then measure endothelial junctional expression/function changes with varied ibrutinib doses in vitro. Rat glioma cells and rodent glioma models were treated with ibrutinib alone (1–10 µM and 25 mg/kg) and in combination with doxil (10–100 µM and 3 mg/kg) to assess additive effects on viability, drug concentrations, tumor volume, endothelial junctional expression and survival. We found that ibrutinib, in a dose-dependent manner, decreased brain endothelial cell–cell adhesion over 24 h, without affecting endothelial cell viability ( p  < 0.005). Expression of tight junction gene and protein expression was decreased maximally 4 h after administration, along with inhibition of efflux transporter, ABCB1, activity. We demonstrated an additive effect of ibrutinib with doxil on rat glioma cells, as seen by a significant reduction in cell viability ( p  < 0.001) and increased CNS doxil concentration in the brain (56 ng/mL doxil alone vs. 74.6 ng/mL combination, p  < 0.05). Finally, Ibrutinib, combined with doxil, prolonged median survival in rodent glioma models (27 vs. 16 days, p  < 0.0001) with brain imaging showing a − 53% versus − 75% volume change with doxil alone versus combination therapy ( p  < 0.05). These findings indicate ibrutinib’s ability to increase brain endothelial permeability via junctional disruption and efflux inhibition, to increase BTB drug entry and prolong rodent glioma model survival. Our results motivate the need to identify other BTB modifiers, all with the intent of improving survival and reducing systemic toxicities.

Alcohol is the most commonly used drug in the United States and alcohol abuse can lead to alcohol use disorder. Alcohol use disorder is a persistent condition and relapse rates following successful remission are high. Many factors have been associated with relapse for alcohol use disorder, but identification of these factors has not been well translated into preventative utility. One potentially important factor, concurrent nicotine use, has not been well investigated as a causal factor in relapse for alcohol use disorder. Nicotine increases the value of other stimuli in the environment and may increase the value of alcohol. If nicotine increases the value of alcohol, then nicotine use during and after treatment may make relapse more probable. In the current study, we investigated the effect of continuous nicotine exposure (using osmotic minipumps to deliver nicotine or saline, depending on group, at a constant rate for 28 days) on resurgence of alcohol seeking in rats. Resurgence is a type of relapse preparation that consists of three phases: Baseline, Alternative Reinforcement, and Resurgence Testing. During Baseline, target responses produced a dipper of alcohol. During Alternative Reinforcement, target responses were extinguished and responses on a chain produced a chocolate pellet. During Resurgence Testing, responses on the chain were also extinguished and a return to responding on the target lever was indicative of resurgence. Multilevel modeling was used to analyze the effect of nicotine on resurgence. Both the nicotine and saline group showed resurgence of alcohol seeking, but there was no difference in the degree of resurgence across groups. Future directions could involve testing alternative drug delivery techniques.

Background A principal protective component of the mammalian blood–brain barrier (BBB) is the high expression of the multidrug efflux transporters P-glycoprotein (P-gp, encoded by ABCB1 ) and ABCG2 (encoded by ABCG2 ) on the lumenal surface of endothelial cells. The zebrafish P-gp homolog Abcb4 is expressed at the BBB and phenocopies human P-gp. Comparatively little is known about the four zebrafish homologs of the human ABCG2 gene: abcg2a , abcg2b , abcg2c , and abcg2d . Here we report the functional characterization and brain tissue distribution of zebrafish ABCG2 homologs. Methods To determine substrates of the transporters, we stably expressed each in HEK-293 cells and performed cytotoxicity and fluorescent efflux assays with known ABCG2 substrates. To assess the expression of transporter homologs, we used a combination of RNAscope in situ hybridization probes and immunohistochemistry to stain paraffin-embedded sections of adult and larval zebrafish. Results We found Abcg2a had the greatest substrate overlap with ABCG2, and Abcg2d appeared to be the least functionally similar. We identified abcg2a as the only homolog expressed at the adult and larval zebrafish BBB, based on its localization to claudin-5 positive brain vasculature. Conclusions These results demonstrate the conserved function of zebrafish Abcg2a and suggest that zebrafish may be an appropriate model organism for studying the role of ABCG2 at the BBB.