A histological survey of green fluorescent protein expression in 'green' mice: implications for stem cell research

AIMS: The transgenic enhanced green fluorescent protein (EGFP) expressing 'green' mouse (C57BL/6-TgN(ACTbEGFP)1Osb) is a widely used tool in stem cell research, where the ubiquitous nature of EGFP expression is critical to track the fate of single or small groups of transplanted haematopoietic stem cells (HSC). Our aim was to investigate this assumed ubiquitous expression by performing a detailed histological survey of EGFP expression in these mice. METHODS: Fluorescent microscopy of frozen tissue sections was used to perform a detailed histological survey of the pattern of EGFP expression in these mice. Flow cytometry was also used to determine the expression pattern in blood and bone marrow. RESULTS: Three patterns of EGFP expression were noted. In most tissues there was an apparently stochastic variegation of the transgene, with individual cell types demonstrating highly variable rates of EGFP expression. Certain specific cell types such as pancreatic ductal epithelium, cerebral cortical neurones and glial cells and glomerular mesangial cells consistently lacked EGFP expression, while others, including pancreatic islet cells, expressed EGFP only at extremely low levels, barely distinguishable from background. Lastly, in the colon and stomach the pattern of EGFP expression was suggestive of clonal inactivation. Only cardiac and skeletal muscle showed near ubiquitous expression. CONCLUSIONS: These findings raise questions regarding the 'ubiquitous' expression of EGFP in these transgenic mice and suggest caution in relying overly on EGFP alone as an infallible marker of donor cell origin.     

Arguments Used in Public Comments to Support or Oppose the US Department of Agriculture’s Minimum Stocking Requirements: A Content Analysis

Background

In 2016, the US Department of Agriculture (USDA)’s Supplemental Nutrition Assistance Program (SNAP) Retailer Rule proposed several changes for SNAP-authorized retailers, including: requiring retailers to have at least 85% of their food sales come from items that are not cooked or heated on site before or after purchase; requiring stores to stock seven varieties of qualifying foods from four staple food groups; requiring stores to carry perishable foods in three of the four staple groups; requiring stores to carry six units of qualifying foods at all times (depth of stock); disqualifying multiple ingredient foods and accessory foods from counting toward depth of stock requirements.

Intracellular pharmacokinetics of once versus twice daily zidovudine and lamivudine in adolescents

Zidovudine (ZDV) and lamivudine (3TC) metabolism to triphosphates (TP) is necessary for antiviral activity. The aims of this study were to compare ZDV-TP and 3TC-TP concentrations in adolescents receiving twice daily (BID) and once daily (QD) regimens and to determine the metabolite concentrations of ZDV and 3TC during chronic therapy on a QD regimen. Human immunodeficiency virus-infected patients (12 to 24 years) taking ZDV (600 mg/day) and 3TC (300 mg/day) as part of a highly active antiretroviral therapy regimen received QD and BID regimens of ZDV and 3TC for 7 to 14 days in a crossover design. Serial blood samples were obtained over 24 h on the QD regimen. Intracellular mono-, di-, and triphosphates for ZDV and 3TC were measured. The median ratio of BID/QD for ZDV-TP predose concentrations was 1.28 (95% confidence interval [CI] = 1.00 to 2.45) and for 3TC-TP was 1.12 (95% CI = 0.81 to 1.96). The typical population estimated half-lives (+/- the standard error of the mean) were 9.1 +/- 0.859 h for ZDV-TP and 17.7 +/- 2.8 h for 3TC-TP. Most patients had detectable levels of the TP of ZDV (24 of 27) and 3TC (24 of 25) 24 h after dosing, and half-lives on a QD regimen were similar to previously reported values when the drugs were given BID. Lower, but not significantly different, concentrations of ZDV-TP were demonstrated in the QD regimen compared to the BID regimen (P = 0.056). Although findings were similar between the BID and QD groups, the lower concentrations of ZDV and the number of patients below the level of detection after 24 h suggests that ZDV should continue to be administered BID.     

Steroid-sparing maintenance immunosuppression is safe and effective after simultaneous liver-kidney transplantation

Optimization of maintenance immunosuppression (mIS) regimens in the transplant recipient requires a balance between sufficient potency to prevent rejection and avoidance of excessive immunosuppression to prevent toxicities and complications. The optimal regimen after simultaneous liver-kidney (SLK) transplantation remains unclear, but small single-center reports have shown success with steroid-sparing regimens. We studied 4184 adult SLK recipients using the Scientific Registry of Transplant Recipients, from March 1, 2002, to February 28, 2017, on tacrolimus-based regimens at 1 year post-transplant. We determined the association between mIS regimen and mortality and graft failure using Cox proportional hazard models. The use of steroid-sparing regimens increased post-transplant, from 16.1% at discharge to 88.0% at 5 years. Using multi-level logistic regression modeling, we found center-level variation to be the major contributor to choice of mIS regimen (ICC 44.5%; 95% CI: 36.2%-53.0%). In multivariate analysis, use of a steroid-sparing regimen at 1 year was associated with a 21% decreased risk of mortality compared to steroid-containing regimens (aHR 0.79, P = .01) and 20% decreased risk of liver graft failure (aHR 0.80, P = .01), without differences in kidney graft loss risk (aHR 0.92, P = .6). Among SLK recipients, the use of a steroid-sparing regimen appears to be safe and effective without adverse effects on patient or graft survival.     

Heart transplant recipients with confirmed 2019 novel coronavirus infection: The Detroit experience

A chronic immunosuppressed state as in solid organ transplant recipients is a reported risk factor for the novel 2019 coronavirus infection. Patients with a history of orthotopic heart transplant (OHT) at a tertiary care transplant center in Detroit, Michigan were retrospectively reviewed from March until May 2020. Clinical parameters and outcomes of 5 OHT recipients and one combined heart–lung recipient with confirmed SARS-CoV-2 were obtained. The cohort was predominately African American males with median age of 59 years (interquartile range, 48.25-73.25). All patients were classified as having mild–moderate disease; none required intubation or ICU admission with no deaths. The most common presenting symptoms were fever and shortness of breath 83% (n = 5), followed by cough and chills 67% (n = 4). All admitted patients (n = 5) received hydroxychloroquine and 3 received high-dose steroids. Antimetabolites were held for 2 patients (33.3%). The calcineurin inhibitor trough goal was decreased in only 1 patient; 3 other patients, without change in goal, required calcineurin inhibitor dosage reduction. Two patients requiring readmission presented 7 and 23 days after initial symptoms onset. In conclusion, our experience with OHT patients infected by the SARS-CoV-2 virus did not have an elevated risk of severe infection. Impact of modifying immunosuppression remains unclear.     

Changes in Burnout and Satisfaction With Work-Life Integration in Physicians and the General US Working Population Between 2011 and 2017

ObjectiveTo evaluate the prevalence of burnout and satisfaction with work-life integration among physicians and other US workers in 2017 compared with 2011 and 2014.Participants and MethodsBetween October 12, 2017, and March 15, 2018, we surveyed US physicians and a probability-based sample of the US working population using methods similar to our 2011 and 2014 studies. A secondary survey with intensive follow-up was conducted in a sample of nonresponders to evaluate response bias. Burnout and work-life integration were measured using standard tools.ResultsOf 30,456 physicians who received an invitation to participate, 5197 (17.1%) completed surveys. Among the 476 physicians in the secondary survey of nonresponders, 248 (52.1%) responded. A comparison of responders in the 2 surveys revealed no significant differences in burnout scores (P=.66), suggesting that participants were representative of US physicians. When assessed using the Maslach Burnout Inventory, 43.9% (2147 of 4893) of the physicians who completed the MBI reported at least one symptom of burnout in 2017 compared with 54.4% (3680 of 6767) in 2014 (P<.001) and 45.5% (3310 of 7227) in 2011 (P=.04). Satisfaction with work-life integration was more favorable in 2017 (42.7% [2056 of 4809]) than in 2014 (40.9% [2718 of 6651]; P<.001) but less favorable than in 2011 (48.5% [3512 of 7244]; P<.001). On multivariate analysis adjusting for age, sex, relationship status, and hours worked per week, physicians were at increased risk for burnout (odds ratio, 1.39; 95% CI, 1.26-1.54; P<.001) and were less likely to be satisfied with work-life integration (odds ratio, 0.77; 95% CI, 0.70-0.85; P<.001) than other working US adults.ConclusionBurnout and satisfaction with work-life integration among US physicians improved between 2014 and 2017, with burnout currently near 2011 levels. Physicians remain at increased risk for burnout relative to workers in other fields.