EGLN1 Inhibition and Rerouting of α-Ketoglutarate Suffice for Remote Ischemic Protection.

Ischemic preconditioning is the phenomenon whereby brief periods of sublethal ischemia protect against a subsequent, more prolonged, ischemic insult. In remote ischemic preconditioning (RIPC), ischemia to one organ protects others organs at a distance. We created mouse models to ask if inhibition of the alpha-ketoglutarate (αKG)-dependent dioxygenase Egln1, which senses oxygen and regulates the hypoxia-inducible factor (HIF) transcription factor, could suffice to mediate local and remote ischemic preconditioning. Using somatic gene deletion and a pharmacological inhibitor, we found that inhibiting Egln1 systemically or in skeletal muscles protects mice against myocardial ischemia-reperfusion (I/R) injury. Parabiosis experiments confirmed that RIPC in this latter model was mediated by a secreted factor. Egln1 loss causes accumulation of circulating αKG, which drives hepatic production and secretion of kynurenic acid (KYNA) that is necessary and sufficient to mediate cardiac ischemic protection in this setting.

Growth differentiation factor 11 is a circulating factor that reverses age-related cardiac hypertrophy.

The most common form of heart failure occurs with normal systolic function and often involves cardiac hypertrophy in the elderly. To clarify the biological mechanisms that drive cardiac hypertrophy in aging, we tested the influence of circulating factors using heterochronic parabiosis, a surgical technique in which joining of animals of different ages leads to a shared circulation. After 4 weeks of exposure to the circulation of young mice, cardiac hypertrophy in old mice dramatically regressed, accompanied by reduced cardiomyocyte size and molecular remodeling. Reversal of age-related hypertrophy was not attributable to hemodynamic or behavioral effects of parabiosis, implicating a blood-borne factor. Using modified aptamer-based proteomics, we identified the TGF-ß superfamily member GDF11 as a circulating factor in young mice that declines with age. Treatment of old mice to restore GDF11 to youthful levels recapitulated the effects of parabiosis and reversed age-related hypertrophy, revealing a therapeutic opportunity for cardiac aging.

Young, proliferative thymic epithelial cells engraft and function in aging thymuses.

The thymus reaches its maximum size early in life and then begins to shrink, producing fewer T cells with increasing age. This thymic decline is thought to contribute to age-related T cell lymphopenias and hinder T cell recovery after bone marrow transplantation. Although several cellular and molecular processes have been implicated in age-related thymic involution, their relative contributions are not known. Using heterochronic parabiosis, we observe that young circulating factors are not sufficient to drive regeneration of the aged thymus. In contrast, we find that resupplying young, engraftable thymic epithelial cells (TECs) to a middle-aged or defective thymus leads to thymic growth and increased T cell production. Intrathymic transplantation and in vitro colony-forming assays reveal that the engraftment and proliferative capacities of TECs diminish early in life, whereas the receptivity of the thymus to TEC engraftment remains relatively constant with age. These results support a model in which thymic growth and subsequent involution are driven by cell-intrinsic changes in the proliferative capacity of TECs, and further show that young TECs can engraft and directly drive the growth of involuted thymuses.

Sarcomas induced in discrete subsets of prospectively isolated skeletal muscle cells.

Soft-tissue sarcomas are heterogeneous cancers that can present with tissue-specific differentiation markers. To examine the cellular basis for this histopathological variation and to identify sarcoma-relevant molecular pathways, we generated a chimeric mouse model in which sarcoma-associated genetic lesions can be introduced into discrete, muscle-resident myogenic and mesenchymal cell lineages. Expression of Kirsten rat sarcoma viral oncogene [Kras(G12V)] and disruption of cyclin-dependent kinase inhibitor 2A (CDKN2A; p16p19) in prospectively isolated satellite cells gave rise to pleomorphic rhabdomyosarcomas (MyoD-, Myogenin- and Desmin-positive), whereas introduction of the same oncogenetic hits in nonmyogenic progenitors induced pleomorphic sarcomas lacking myogenic features. Transcriptional profiling demonstrated that myogenic and nonmyogenic Kras; p16p19(null) sarcomas recapitulate gene-expression signatures of human rhabdomyosarcomas and identified a cluster of genes that is concordantly up-regulated in both mouse and human sarcomas. This cluster includes genes associated with Ras and mechanistic target of rapamycin (mTOR) signaling, a finding consistent with activation of the Ras and mTOR pathways both in Kras; p16p19(null) sarcomas and in 26-50% of human rhabdomyosarcomas surveyed. Moreover, chemical inhibition of Ras or mTOR signaling arrested the growth of mouse Kras; p16p19(null) sarcomas and of human rhabdomyosarcoma cells in vitro and in vivo. Taken together, these data demonstrate the critical importance of lineage commitment within the tumor cell-of-origin in determining sarcoma histotype and introduce an experimental platform for rapid dissection of sarcoma-relevant cellular and molecular events.

Guidance for prevention and management of COVID-19 in children and adolescents: A consensus statement from the Pediatric Infectious Diseases Society Pediatric COVID-19 Therapies Taskforce.

BACKGROUND: Since November 2019, the SARS-CoV-2 pandemic has created challenges for preventing and managing COVID-19 in children and adolescents. Most research to develop new therapeutic interventions or to repurpose existing ones has been undertaken in adults, and although most cases of infection in pediatric populations are mild, there have been many cases of critical and fatal infection. Understanding the risk factors for severe illness and the evidence for safety, efficacy, and effectiveness of therapies for COVID-19 in children is necessary to optimize therapy. METHODS: A panel of experts in pediatric infectious diseases, pediatric infectious diseases pharmacology, and pediatric intensive care medicine from 21 geographically diverse North American institutions was re-convened. Through a series of teleconferences and web-based surveys and a systematic review with meta-analysis of data for risk factors, a guidance statement comprising a series of recommendations for risk stratification, treatment, and prevention of COVID-19 was developed and refined based on expert consensus. RESULTS: There are identifiable clinical characteristics that enable risk stratification for patients at risk for severe COVID-19. These risk factors can be used to guide the treatment of hospitalized and non-hospitalized children and adolescents with COVID-19 and to guide preventative therapy where options remain available.

Protective behavioral strategies and alcohol-related outcomes: The moderating effects of drinking refusal self-efficacy and sex.

The investigation of drinking refusal self-efficacy and alcohol protective behavioral strategies (PBSA) has revealed inconsistent results. Sex may be one factor that plays a role in these results given the demonstrable differences between the alcohol use behaviors of men and women. The current study examined the moderating effects of drinking refusal self-efficacy and sex on the relationships that PBSA subtypes have with alcohol outcomes for traditional age undergraduate students (18-25 years of age; 81% women; 60% White). Results showed negative associations between manner of drinking PBSA and alcohol consumption for individuals with high levels of drinking refusal self-efficacy but not low levels of drinking refusal self-efficacy. However, manner of drinking PBSA was positively associated with alcohol-related negative consequences for men but not for women. Results also showed negative associations between stopping and limiting drinking PBSA and alcohol related negative consequences for individuals with high levels of drinking refusal self-efficacy but not low levels of drinking refusal self-efficacy. It appears that addressing drinking refusal self-efficacy within the context of PBSA is valuable for traditional college students.

Optimizing accuracy of sampling protocols to measure nutrient content of solid manure.

Precise applications of manure to cropland can help optimize productivity and minimize environmental nutrient losses. Applying manure precisely is a challenge because the nutrient content of manures is inherently variable and the accuracy of sampling protocols are unknown. This study aimed to quantify the accuracy of sampling protocols for static solid manure piles considering both the number and depth of grab samples entering a composite sample. Over 35 grab samples were collected from each of ten static piles of dairy manure in California's Central Valley. Grab samples were individually analyzed for dry matter (DM), ash, total nitrogen, potassium, and phosphorous concentrations. Resampling simulations quantified the precision and bias of sampling protocols varying in both grab sample number and depth. Results showed that number of grab samples required for measurements to meet an accuracy standard of ±10% of the true value varied significantly by pile makeup. Over 25 grab samples were often required for multi-source manure piles, where an average of six grab samples were required from single source piles. The DM concentration of manure piles decreased at depths greater than 0.4 m, and sampling simulations showed that measurements were biased unless 70-80% of grab samples were collected from the pile interior. Both the number and location of grab samples necessary to create a representative composite require resource investments by farmers, and should be considered to manage nutrient applications cropland.

Optimizing accuracy of protocols for measuring dry matter and nutrient yield of forage crops.

Farmers around the world must precisely manage nutrients applied to and removed from crop fields to maintain production and without causing nutrient pollution. This study is the first to quantify the baseline accuracy of current industry measurement protocols and achievable accuracy from intensifying protocols for measuring dry matter (DM), nitrogen (N), potassium (K), and phosphorus (P) yields from forage crops harvested for silage. The 'true' DM and nutrient yields of three fields each of corn, sorghum, and small grain were intensively measured by weighing and sampling every truckload of harvested forage. Simulations quantified the accuracy of practical sampling protocols by repeatedly subsampling the complete dataset for each field to measure average truckload weight and average DM and nutrient concentrations. Then uncertainty was propagated to DM, N, P, and K yield calculations using standard error equations. Yields measured using current industry protocols diverged from the true yields of some fields by more than ±40%, emphasizing the need for improved protocols. This study shows that improving average DM and nutrient concentration measurements is unlikely to improve accuracy of yield measurements if average load weight is not precisely measured. Accuracy did not come within 27% of true yields without weighing all truckloads on some fields even when DM and nutrient concentration measurements were perfectly accurate. Once all truckloads were weighed, the timing of forage sample collection to measure average DM concentration had the greatest impact on accuracy; precision improved by an average of 6.2% when >3 samples were evenly spaced throughout the harvest compared to the same number of consecutive samples. All crop fields are affected by within field variation in growing conditions that results in heterogeneity in DM and nutrient yield. Globally, this study provides foundational methodology to quantitatively evaluate and improve yield measurement protocols that ultimately support sustainable crop production.