Polycomb contraction differentially regulates terminal human hematopoietic differentiation programs

Background

Lifelong production of the many types of mature blood cells from less differentiated progenitors is a hierarchically ordered process that spans multiple cell divisions. The nature and timing of the molecular events required to integrate the environmental signals, transcription factor activity, epigenetic modifications, and changes in gene expression involved are thus complex and still poorly understood. To address this gap, we generated comprehensive reference epigenomes of 8 phenotypically defined subsets of normal human cord blood.

Results

We describe a striking contraction of H3K27me3 density in differentiated myelo-erythroid cells that resembles a punctate pattern previously ascribed to pluripotent embryonic stem cells. Phenotypically distinct progenitor cell types display a nearly identical repressive H3K27me3 signature characterized by large organized chromatin K27-modification domains that are retained by mature lymphoid cells but lost in terminally differentiated monocytes and erythroblasts. We demonstrate that inhibition of polycomb group members predicted to control large organized chromatin K27-modification domains influences lymphoid and myeloid fate decisions of primary neonatal hematopoietic progenitors in vitro. We further show that a majority of active enhancers appear in early progenitors, a subset of which are DNA hypermethylated and become hypomethylated and induced during terminal differentiation.

Conclusion

Primitive human hematopoietic cells display a unique repressive H3K27me3 signature that is retained by mature lymphoid cells but is lost in monocytes and erythroblasts. Intervention data implicate that control of this chromatin state change is a requisite part of the process whereby normal human hematopoietic progenitor cells make lymphoid and myeloid fate decisions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01315-1.

Prediction Model Performance With Different Imputation Strategies: A Simulation Study Using a North American ICU Registry

OBJECTIVES

To evaluate the performance of pragmatic imputation approaches when estimating model coefficients using datasets with varying degrees of data missingness.

DESIGN

Performance in predicting observed mortality in a registry dataset was evaluated using simulations of two simple logistic regression models with age-specific criteria for abnormal vital signs (mentation, systolic blood pressure, respiratory rate, WBC count, heart rate, and temperature). Starting with a dataset with complete information, increasing degrees of biased missingness of WBC and mentation were introduced, depending on the values of temperature and systolic blood pressure, respectively. Missing data approaches evaluated included analysis of complete cases only, assuming missing data are normal, and multiple imputation by chained equations. Percent bias and root mean square error, in relation to parameter estimates obtained from the original data, were evaluated as performance indicators.

SETTING

Data were obtained from the Virtual Pediatric Systems, LLC, database (Los Angeles, CA), which provides clinical markers and outcomes in prospectively collected records from 117 PICUs in the United States and Canada.

PATIENTS

Children admitted to a participating PICU in 2017, for whom all required data were available.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Simulations demonstrated that multiple imputation by chained equations is an effective strategy and that even a naive implementation of multiple imputation by chained equations significantly outperforms traditional approaches: the root mean square error for model coefficients was lower using multiple imputation by chained equations in 90 of 99 of all simulations (91%) compared with discarding cases with missing data and lower in 97 of 99 (98%) compared with models assuming missing values are in the normal range. Assuming missing data to be abnormal was inferior to all other approaches.

CONCLUSIONS

Analyses of large observational studies are likely to encounter the issue of missing data, which are likely not missing at random. Researchers should always consider multiple imputation by chained equations (or similar imputation approaches) when encountering even only small proportions of missing data in their work.

Mobile Text Messaging to Improve Medication Adherence and Viral Load in a Vulnerable Canadian Population Living With Human Immunodeficiency Virus: A Repeated Measures Study

Background

Combination antiretroviral therapy (cART) as treatment for human immunodeficiency virus (HIV) infection is effective and available, but poor medication adherence limits benefits, particularly in vulnerable populations. In a Kenyan randomized controlled trial, a weekly text-messaging intervention (WelTel) improved cART adherence and HIV viral load (VL). Despite growing evidence for short message service (SMS) text-message interventions in HIV care, there is a paucity of data utilizing these interventions in marginalized or female cohorts.

Objective

This study was undertaken to assess whether the standardized WelTel SMS text-message intervention applied to a vulnerable, predominantly female, population improved cART adherence and VL.

Methods

We conducted a repeated measures study of the WelTel intervention in high-risk HIV-positive persons by measuring change in VL, CD4 count, and self-reported adherence 12 months before and 12 months after the WelTel intervention was introduced. Inclusion criteria included VL ≥200 copies/mL, indication for treatment, and meeting vulnerability criteria. Participants were given a mobile phone with unlimited texting (where required), and weekly check-in text messages were sent for one year from the WelTel computer platform. Clinical data were collected for control and intervention years. Participants were followed by a multidisciplinary team in a clinical setting. Outcomes were assessed using Wilcoxon signed ranks tests for change in CD4 and VL from control year to study end and mixed-effects logistic regressions for change in cART adherence and appointment attendance. A secondary analysis was conducted to assess the effect of response rate on the outcome by modeling final log₁₀ VL by number of responses while controlling for mean log₁₀ VL in the control year.

Results

Eighty-five participants enrolled in the study, but 5 withdrew (final N=80). Participants were predominantly female (90%, 72/80) with a variety of vulnerabilities. Mean VL decreased from 1098 copies/mL in the control year to 439 copies/mL at study end (P=.004). Adherence to cART significantly improved (OR 1.14, IQR 1.10-1.18; P<.001), whereas appointment attendance decreased slightly with the intervention (OR 0.81, IQR 0.67-0.99; P=.03). A response was received for 46.57% (1753/3764) of messages sent and 9.62% (362/3764) of text messages sent were replied to with a problem. An outcome analysis examining relationship between reply rate and VL did not meet statistical significance (P=.07), but may be worthy of investigating further in a larger study.

Conclusions

WelTel may be an effective tool for improving cART adherence and reducing VLs among high-risk, vulnerable HIV-positive persons.

Trial Registration

Clinicaltrials.gov NCT02603536; https://clinicaltrials.gov/ct2/show/NCT02603536 (Archived by WebCite at http://www.webcitation.org/6qK57zCwv)

An online tests catalog for clinical laboratories

An attempt to integrate an online catalog for clinical laboratory tests in a university hospital medical computing environment is presented here. The need for such a catalog is evident, due to the dynamic changes in the area, new tests, and new test methods. Physicians are able to access the catalog through department terminals. The catalog has been designed and implemented as a relational database, including seven tables. Context-sensitive help screens are available at any step, as well as specific instructions for each laboratory.

Rates of sickness absenteeism among employees of a modern hospital: the role of demographic and occupational factors

Sickness absenteeism, of hospital employees particularly, is a problem of concern due to its negative economic and morale impacts. The aim of the first stage of the study was to identify according to some demographic (sex, age, marital status) and occupational (occupational group, duration of hospital employment) variables those groups of hospital employees who are at higher risk of sickness absenteeism. A comparison with the data of the study performed in the same hospital about 15 years ago showed a rise in the duration of absences with a simultaneous reduction in their incidence. Sickness absenteeism was higher among female, mainly unskilled, workers, presently or previously married, aged from 45 to 60, and employed in the hospital for over ten years. Continuous social and medical surveillance of these employees is suggested as a promising way of reducing sickness absenteeism.