Adverse reproductive and developmental effects in Xenopus from insufficient boron

Frog embryo teratogenesis assay—Xenopus (FETAX) was utilized as a model system to evaluate the effects on embryo-larval development at various low boron (B) exposure levels in the culture media. Concentrations tested ranged from <1 to 5000 μg B/L. A statistically significant (P < 0.05) increase in malformations was observed at ≤ 3 μg B/L, but not at the greater concentrations. Abnormal development of the gut, craniofacial region and eye, visceral edema, and kinking of the tail musculature (abnormal myotome development) and notochord were observed. In subsequent studies, adult frogs were maintained for 28 d on two diets: (1) low B (LB, 62 μg B/kg) or (2) boric acid supplemented (BA, 1851 μg B/kg); the frogs were subsequently mated, and their offspring were cultured in media containing various levels of B. Results of the 28-d depletion studies indicated that frogs maintained under LB conditions produced a greater proportion of (1) necrotic eggs and (2) fertilized embryos, which abnormally gastrulated at a greater rate and were substantially less viable than embryos from frogs fed the BA diet. Malformations similar to those seen in the initial study were observed in embryos from the B-depleted adults maintained in an LB environment; 28 d on the LB diet enhanced the incidence of malformations associated with the LB culture media. These abnormalities were not observed in embryos cultured in ≥4 μg B/L from adults cultured on the BA diet. These studies showed that insufficient B reproducibly interfered with normalXenopus laevis development during organogenesis, substantially impaired normal reproductive function in adult frogs, and thus represent the first studies demonstrating the nutritional essentiality of B in an amphibian species.     

Staphylococcus aureus genetic loci impacting growth and survival in multiple infection environments

The Gram-positive bacterium Staphylococcus aureus infects diverse tissues and causes a wide spectrum of diseases, suggesting that it possesses a repertoire of distinct molecular mechanisms promoting bacterial survival in disparate in vivo environments. Signature-tag transposon mutagenesis screening of a 1520-member library identified numerous S. aureus genetic loci affecting growth and survival in four complementary animal infection models including mouse abscess, bacteraemia and wound and rabbit endocarditis. Of a total of 237 in vivo attenuated mutants identified by the murine models, less than 10% showed attenuation in all three models, emphasizing the advantage of screening in diverse disease environments. The largest gene class identified by these analyses encoded peptide and amino acid transporters, some of which were important for S. aureus survival in all animal infection models tested. The identification of staphylococcal loci affecting growth, persistence and virulence in multiple tissue environments provides insight into the complexities of human infection and on the molecular mechanisms that could be targeted by new antibacterial therapies.     

Beneficial effect of fluorocarbon emulsion media on the function of neuromuscular preparations in vitro

The effects of liquid fluorocarbons as bathing media were determined by use of in vitro neuromuscular preparations. Rat hemidiaphragms were bathed in either oxygenated fluorocarbon (FC) emulsion or standard oxygenated Krebs solution. Contractile force in response to simple supramaximal nerve stimuli as well as to high frequency stimulation was greater, while twitch:tetanus ratio was smaller in FC emulsion. With such medium, post-tetanic potentiation of contraction was also more consistently observed. Indirectly stimulated diaphragms survived longer in FC emulsion. After cessation of oxygenation, oxygen tension (ρO(2)) of the medium declined more rapidly with Krebs than with FC emulsion; ρO(2) directly correlated with force of contraction. Similarly, in the chick biventer cervicis preparation, FC emulsion enhanced nerve-stimulated force of contraction; returning the preparation to standard Krebs solution reversed this phenomenon. Dose-resonse curves of muscle contraction in response to acetycholine and KCl administration were shifted upward during FC emulsion superfusion. Frequency of miniature endplate potentials was lower in FC emulsion than that observed in Krebs solution, measured from the same cell of the rat diaphragm. Resting membrane potentials were also greater in muscle cells sampled from FC emulsion-bathed preparations. These data suggest that FC emulsion is superior to standard Krebs solution as a bathing medium for in vitro neuromuscular preparations by virtue of the high solubility of oxygen in it.     

Molecular subtyping and genomic profiling expand precision medicine in refractory metastatic triple-negative breast cancer: the FUTURE trial

Triple-negative breast cancer (TNBC) is a highly heterogeneous disease, and molecular subtyping may result in improved diagnostic precision and targeted therapies. Our previous study classified TNBCs into four subtypes with putative therapeutic targets. Here, we conducted the FUTURE trial (ClinicalTrials.gov identifier: {"type":"clinical-trial","attrs":{"text":"NCT03805399","term_id":"NCT03805399"}}NCT03805399), a phase Ib/II subtyping-based and genomic biomarker-guided umbrella trial, to evaluate the efficacy of these targets. Patients with refractory metastatic TNBC were enrolled and stratified by TNBC subtypes and genomic biomarkers, and assigned to one of these seven arms: (A) pyrotinib with capecitabine, (B) androgen receptor inhibitor with CDK4/6 inhibitor, (C) anti PD-1 with nab-paclitaxel, (D) PARP inhibitor included, (E) and (F) anti-VEGFR included, or (G) mTOR inhibitor with nab-paclitaxel. The primary end point was the objective response rate (ORR). We enrolled 69 refractory metastatic TNBC patients with a median of three previous lines of therapy (range, 1–8). Objective response was achieved in 20 (29.0%, 95% confidence interval (CI): 18.7%–41.2%) of the 69 intention-to-treat (ITT) patients. Our results showed that immunotherapy (arm C), in particular, achieved the highest ORR (52.6%, 95% CI: 28.9%–75.6%) in the ITT population. Arm E demonstrated favorable ORR (26.1%, 95% CI: 10.2%–48.4% in the ITT population) but with more high grade (≥ 3) adverse events. Somatic mutations of TOP2A and CD8 immunohistochemical score may have the potential to predict immunotherapy response in the immunomodulatory subtype of TNBC. In conclusion, the phase Ib/II FUTURE trial suggested a new concept for TNBC treatment, demonstrating the clinical benefit of subtyping-based targeted therapy for refractory metastatic TNBC.Subject terms: Breast cancer, Targeted therapies     

Modeling the epidemiological impact of the UNAIDS 2025 targets to end AIDS as a public health threat by 2030

BackgroundUNAIDS has established new program targets for 2025 to achieve the goal of eliminating AIDS as a public health threat by 2030. This study reports on efforts to use mathematical models to estimate the impact of achieving those targets.Methods and findingsWe simulated the impact of achieving the targets at country level using the Goals model, a mathematical simulation model of HIV epidemic dynamics that includes the impact of prevention and treatment interventions. For 77 high-burden countries, we fit the model to surveillance and survey data for 1970 to 2020 and then projected the impact of achieving the targets for the period 2019 to 2030. Results from these 77 countries were extrapolated to produce estimates for 96 others. Goals model results were checked by comparing against projections done with the Optima HIV model and the AIDS Epidemic Model (AEM) for selected countries. We included estimates of the impact of societal enablers (access to justice and law reform, stigma and discrimination elimination, and gender equality) and the impact of Coronavirus Disease 2019 (COVID-19). Results show that achieving the 2025 targets would reduce new annual infections by 83% (71% to 86% across regions) and AIDS-related deaths by 78% (67% to 81% across regions) by 2025 compared to 2010. Lack of progress on societal enablers could endanger these achievements and result in as many as 2.6 million (44%) cumulative additional new HIV infections and 440,000 (54%) more AIDS-related deaths between 2020 and 2030 compared to full achievement of all targets. COVID-19–related disruptions could increase new HIV infections and AIDS-related deaths by 10% in the next 2 years, but targets could still be achieved by 2025. Study limitations include the reliance on self-reports for most data on behaviors, the use of intervention effect sizes from published studies that may overstate intervention impacts outside of controlled study settings, and the use of proxy countries to estimate the impact in countries with fewer than 4,000 annual HIV infections.ConclusionsThe new targets for 2025 build on the progress made since 2010 and represent ambitious short-term goals. Achieving these targets would bring us close to the goals of reducing new HIV infections and AIDS-related deaths by 90% between 2010 and 2030. By 2025, global new infections and AIDS deaths would drop to 4.4 and 3.9 per 100,000 population, and the number of people living with HIV (PLHIV) would be declining. There would be 32 million people on treatment, and they would need continuing support for their lifetime. Incidence for the total global population would be below 0.15% everywhere. The number of PLHIV would start declining by 2023.

John Stover and co-workers assess the potential health impacts of UNAIDS’ HIV/AIDS targets.     

The beta -globin recombinational hotspot reduces the effects of strong selection around HbC, a recently arisen mutation providing resistance to malaria

Recombination is expected to reduce the effect of selection on the extent of linkage disequilibrium (LD), but the impact that recombinational hotspots have on sites linked to selected mutations has not been investigated. We empirically determine chromosomal linkage phase for 5.2 kb spanning the beta -globin gene and hotspot. We estimate that the HbC mutation, which is positively selected because of malaria, originated <5,000 years ago and that selection coefficients are 0.04-0.09. Despite strong selection and the recent origin of the HbC allele, recombination (crossing-over or gene conversion) is observed within 1 kb 5' of the selected site on more than one-third of the HbC chromosomes sampled. The rapid decay in LD upstream of the HbC allele demonstrates the large effect the ss-globin hotspot has in mitigating the effects of positive selection on linked variation.     

Interaction of C1q and mannan-binding lectin (MBL) with C1r, C1s, MBL-associated serine proteases 1 and 2, and the MBL-associated protein MAp19

Mannan-binding lectin (MBL) and C1q activate the complement cascade via attached serine proteases. The proteases C1r and C1s were initially discovered in a complex with C1q, whereas the MBL-associated serine proteases 1 and 2 (MASP-1 and -2) were discovered in a complex with MBL. There is controversy as to whether MBL can utilize C1r and C1s or, inversely, whether C1q can utilize MASP-1 and 2. Serum deficient in C1r produced no complement activation in IgG-coated microwells, whereas activation was seen in mannan-coated microwells. In serum, C1r and C1s were found to be associated only with C1q, whereas MASP-1, MASP-2, and a third protein, MAp19 (19-kDa MBL-associated protein), were found to be associated only with MBL. The bulk of MASP-1 and MAp19 was found in association with each other and was not bound to MBL or MASP-2. The interactions of MASP-1, MASP-2, and MAp19 with MBL differ from those of C1r and C1s with C1q in that both high salt concentrations and calcium chelation (EDTA) are required to fully dissociate the MASPs or MAp19 from MBL. In the presence of calcium, most of the MASP-1, MASP-2, and MAp19 emerged on gel-permeation chromatography as large complexes that were not associated with MBL, whereas in the presence of EDTA most of these components formed smaller complexes. Over 95% of the total MASPs and MAp19 found in serum are not complexed with MBL.