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.
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.
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.
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.
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.
Aim
To describe the global insulin market.
Methods
Market intelligence data, United Nations Commodity Trade Statistics for insulin trade, the International Medical Products Price Guide for prices of ...human insulin and additional web searches were used as data sources. These sources were combined to gain further insight into possible links among market, trade flows and prices. Descriptive statistics and Spearman's rank order correlation were used for the analysis.
Results
A total of 34 insulin manufacturers were identified. Most countries and territories are reliant on a limited number of supplying countries. The overall median (interquartile range) government procurement price for a 10‐ml, 100‐IU/ml vial during the period 1996–2013 equivalent was US$4.3 (US$ 3.8–4.8), with median prices in Africa (US$ 4.7) and low‐ (US$ 6.9) and low‐ to middle‐ (US$ 4.7) income countries being higher over this period. The relationships between price and quantity of insulin (Spearman's r=0.046; P>0.1) and number of import links (Spearman's r=0.032; P>0.1) were weak. The links between price and percentage of total insulin from a country where a ‘big three' manufacturer produces insulin (Spearman's r=0.294; P<0.05) and total insulin from the main import link (Spearman's r=–0.392; P<0.05) were stronger.
Conclusions
This research shows the high variability of insulin prices and the reliance on a few sources, both companies and countries, for global supply. In addressing access to insulin, countries need to use existing price data to negotiate prices, and mechanisms need to be developed to foster competition and security of supply of insulin, given the limited number of truly global producers.
What's new?
Very little is known about the global insulin market and its possible impact on access to insulin in a given country.
Current evidence, using traditional methodological approaches, suggests poor availability and affordability of insulin in specific contexts.
Insight is provided into the insulin market in terms of numbers of insulin‐producing companies, trade flows of insulin, global prices of insulin and the possible impact of different factors on the price of insulin for individual countries.
This study uses data sources traditionally not used in health research and offers a perspective on how to gain a better understanding of the global pharmaceutical market and access to medicines.
Aim
It is well‐known that enterococci are abundant in the environment; however, the role of surface water as a reservoir of antimicrobial‐resistant enterococci remains largely undefined. In this ...study, surface water samples were collected over a 2‐year period from the Upper Oconee watershed, Athens, GA to examine enterococci and their antimicrobial resistance.
Methods and Results
Approximately 97% (445/458) of the samples were positive for enterococci and a total of 637 enterococci were isolated. The predominant species were Enterococcus casseliflavus (33·6%) followed by Enterococcus faecalis (26·5%) and Enterococcus hirae (13·2%). Regardless of species, the highest levels of resistance were to lincomycin (88·5%) and tetracycline (13%); isolates also exhibited resistance to newer antimicrobials, daptomycin (8·9%) and tigecycline (6·4%). Multidrug resistance (resistance ≥3 antimicrobial classes) was observed to as many as five classes of antimicrobials. Resistant enterococci appeared to be randomly dispersed over the seasons rather than clustered by species or antimicrobial resistance.
Conclusions
This study demonstrated that surface waters contain a large population of diverse species of antimicrobial‐resistant enterococci, including resistance to new antimicrobials.
Significance and Impact of the Study
These results may indicate the potential of human intestinal illness and/or colonization of the human gut with resistant enterococci as enterococci correlate with increased disease risk to humans during recreational exposure to water.
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.
The Norway rat (Rattus norvegicus) is a reservoir of many zoonotic pathogens and lives in close proximity to humans in urban environments. Human infection with rodent-borne disease occurs either ...directly through contact with a rat or its excreta, or indirectly via arthropod vectors such as fleas and ticks. Here, we report on the diversity and abundance of ectoparasitic arthropod species and associated pathogenic bacteria from 133 Norway rats trapped over a 10-mo period in Manhattan, New York, NY. Norway rats were host to the tropical rat mite Ornithonyssus bacoti (Hirst), the spiny rat mite (Laelaps echidnina Berlese), Laelaps nuttalli Hirst, the spined rat louse Polyplax spinulosa (Burmeister), and the Oriental rat flea (Xenopsylla cheopis) (Rothschild), with an average of 1.7 species per individual. A flea index of 4.1 X. cheopis was determined, whereas previous studies in New York City reported 0.22 fleas per rat. Multiple species of pathogenic Bartonella were identified from Oriental rat fleas that were related to Bartonella tribocorum, Bartonella rochalimae, and Bartonella elizabethae. However, no evidence of Yersinia pestis or Rickettsia spp. infection was detected in fleas. The identification of multiple medically important ectoparasite species in New York City underscores the need for future efforts to fully characterize the diversity and distribution of ectoparasites on Norway rats, and assess the risk to humans of vector-borne disease transmission.
Objective
To assess the effectiveness of introducing condom‐catheter uterine balloon tamponade (UBT) for postpartum haemorrhage (PPH) management in low‐ and middle‐income settings.
Design
Stepped ...wedge, cluster‐randomised trial.
Setting
Eighteen secondary‐level hospitals in Uganda, Egypt and Senegal.
Population
Women with vaginal delivery from October 2016 to March 2018.
Methods
Use of condom‐catheter UBT for PPH management was introduced using a half‐day training and provision of pre‐packaged UBT kits. Hospitals were randomised to when UBT was introduced. The incident rate (IR) of study outcomes was compared in the control (i.e. before UBT) and intervention (i.e. after UBT) periods. Mixed effects regression models accounted for clustering (random effect) and time period (fixed effect).
Main outcome measures
Combined IR of PPH‐related invasive surgery and/or maternal death.
Results
There were 28 183 and 31 928 deliveries in the control and intervention periods, respectively. UBT was used for 9/1357 and 55/1037 women diagnosed with PPH in control and intervention periods, respectively. PPH‐related surgery or maternal death occurred in 19 women in the control period (IR = 6.7/10 000 deliveries) and 37 in the intervention period (IR = 11.6/10 000 deliveries). The adjusted IR ratio was 4.08 (95% confidence interval 1.07–15.58). Secondary outcomes, including rates of transfer and blood transfusion, were similar in the trial periods.
Conclusions
Introduction of condom‐catheter UBT in these settings did not improve maternal outcomes and was associated with an increase in the combined incidence of PPH‐related surgery and maternal death. The lack of demonstrated benefit of UBT introduction with respect to severe outcomes warrants reflection on its role.
Tweetable
Stepped wedge trial shows UBT introduction does not reduce the combined incidence of PPH‐related surgery or death.
Tweetable
Stepped wedge trial shows UBT introduction does not reduce the combined incidence of PPH‐related surgery or death.
Quail (Coturnix japonica) is processed and marketed as fresh meat, with limited shelf life. The objective of this study was to evaluate the efficacy of antimicrobial interventions during slaughter on ...reducing Salmonella and Campylobacter contamination and to determine the microbiological shelf life of quail during refrigerated (4°C) storage. Three antimicrobials, peracetic acid (400 ppm; PAA), Citrilow (pH 1.2), and Cecure (cetylpyridinium chloride CPC, 450 ppm), along with a water and no-treatment control were evaluated. Quail carcasses (n = 75) were inoculated with a cocktail of nalidixic acid–resistant Salmonella Typhimurium and gentamicin-resistant Campylobacter coli. After 30 min of attachment time, quail carcasses were submerged in each antimicrobial solution for 20 s with air agitation. Noninoculated quail carcasses (n = 25) were similarly treated, packaged, and stored under refrigeration (4°C). Aerobic plate counts (APC), psychrotroph counts (PC), Enterobacteriaceae counts (ENT), total coliform counts (TCC), and Escherichia coli counts on quail carcasses were determined on 1, 4, 7, and 10 d. Salmonella and Campylobacter populations were determined by plating on Petrifilm APC supplemented with 200-ppm nalidixic acid and Campy Cefex agar supplemented with 200-ppm gentamycin, respectively. No significant reductions in (P > 0.01 log cfu/mL) in APC, PC, ENT, TCC, and E. coli counts were observed on carcasses submerged in water. However, treatments with PAA, Citrilow, and CPC significantly reduced (P ≤ 0.05) Salmonella and Campylobacter coli contamination. Citrilow showed greater (P ≤ 0.05) reduction in Salmonella and Campylobacter population (1.90 and 3.82 log cfu/mL reduction, respectively) to PAA and CPC. Greater (P ≤ 0.05) reductions in APC, PC, ENT, TCC, and E. coli counts (2.22, 1.26, 1.47, 1.52, and 1.59 log cfu/mL, respectively) were obtained with the application of CPC. Application of antimicrobial interventions resulted in a reduction in Campylobacter and Salmonella, APC, PC, and ENT populations after treatments (day 0) and throughout the storage period (day 10). Use of antimicrobial interventions after slaughter can improve the microbiological safety and shelf life of quail.
Enterococcus cecorum has been implicated as a possible cause of disease in poultry. However, the characteristics that contribute to pathogenesis of Ent. cecorum in poultry have not been defined. In ...this study, Ent. cecorum from carcass rinsates (n = 75) and diseased broilers and broiler breeders (n = 30) were compared based upon antimicrobial resistance phenotype, the presence of virulence determinants and genetic relatedness using pulsed‐field gel electrophoresis (PFGE). Of the 16 antimicrobials tested, Ent. cecorum from carcass rinsates and clinical cases were resistant to ten and six of the antimicrobials, respectively. The majority of Ent. cecorum from carcass rinsates was resistant to lincomycin (54/75; 72%) and tetracycline (46/75; 61·3%) while the highest level of resistance among clinical Ent. cecorum was to tetracycline (22/30; 73·3%) and erythromycin (11/30; 36·7%). Multidrug resistance (resistance to ≥2 antimicrobials) was identified in Ent. cecorum from carcass rinsates (53/75; 70·7%) and diseased poultry (18/30; 60%). Of the virulence determinants tested, efaAfm was present in almost all of the isolates (104/105; 99%). Using PFGE, the majority of clinical isolates clustered together; however, a few clinical isolates grouped with Ent. cecorum from carcass rinsates. These data suggest that distinguishing the two groups of isolates is difficult based upon the characterization criteria used. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, antimicrobial resistance phenotype, virulence gene profile and genetic relatedness of Enterococcus cecorum isolated from diseased broiler chickens and poultry carcass rinsates were determined. The majority of isolates from both groups were multidrug resistant and harboured few virulence determinants. Results from this study suggest that clinical Ent. cecorum and Ent. cecorum from poultry carcass rinsates may share a common genetic background; clinical Ent. cecorum possess virulence determinants that have not been previously described for this species. Elucidation of those unknown virulence determinants is important for understanding the pathogenesis of Ent. cecorum infections in poultry.
Salmonella enterica is not able to grow at water activity (aw) levels below 0.94, but it can survive in low-aw foods for long periods of time. Temperature, aw, substrate, and serotype affect its ...persistence. The aim of this study was to evaluate the influence of temperature and aw on the relative persistence among four serotypes of Salmonella enterica in low-aw whey protein powder. Whey protein powder was equilibrated to aws 0.18 ± 0.02 and 0.54 ± 0.03, inoculated with a cocktail of Salmonella serovars (Agona, Tennessee, Montevideo, and Typhimurium), vacuum sealed, and stored at 36°C for 6 months and at 70°C for 48 h. Presumptive Salmonella colonies (30 to 32) were randomly picked from each plate at the end of each survival study. PCR multiplex serotyping was used to identify the isolates. A multinomial mixed logistic model with Salmonella Tennessee as a reference was used to test for significant differences in frequency distribution of the surviving serotypes. Salmonella Tennessee and Salmonella Agona were the most prevalent surviving serotypes, followed in decreasing order by Salmonella Montevideo and Salmonella Typhimurium. Statistical analysis indicated that temperature (P = 0.003) and aw (P = 0.012) influenced the relative prevalence of the Salmonella serotypes. If other environmental conditions are equal, Salmonella Tennessee is better able to survive than Salmonella Montevideo and Salmonella Typhimurium at higher temperatures and higher aw levels in low-aw whey protein powder held at 36 and 70°C. The relative prevalence of Salmonella Agona to Salmonella Tennessee did not change with increasing temperature (P = 0.211) or aw (P = 0.453). These results should be considered in risk assessment and when developing predictive models for survival of Salmonella in low-aw foods.
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