Sequence-dependent mechanochemical coupling of helicase translocation and unwinding at single-nucleotide resolution.

We used single-molecule picometer-resolution nanopore tweezers (SPRNT) to resolve the millisecond single-nucleotide steps of superfamily 1 helicase PcrA as it translocates on, or unwinds, several kilobase-long DNA molecules. We recorded more than two million enzyme steps under various assisting and opposing forces in diverse adenosine tri- and diphosphate conditions to comprehensively explore the mechanochemistry of PcrA motion. Forces applied in SPRNT mimic forces and physical barriers PcrA experiences in vivo, such as when the helicase encounters bound proteins or duplex DNA. We show how PcrA's kinetics change with such stimuli. SPRNT allows for direct association of the underlying DNA sequence with observed enzyme kinetics. Our data reveal that the underlying DNA sequence passing through the helicase strongly influences the kinetics during translocation and unwinding. Surprisingly, unwinding kinetics are not solely dominated by the base pairs being unwound. Instead, the sequence of the single-stranded DNA on which the PcrA walks determines much of the kinetics of unwinding.

Drug-Induced and Malignancy-Associated Neutrophilic Dermatoses in Patients with Hematologic Malignancies: A Single Institution Experience.

INTRODUCTION: Neutrophilic dermatoses (NDs) often occur secondary to inflammatory conditions, medication exposure, and hematologic malignancy. While malignancy-associated NDs (MA-NDs) have been well reported among those with hematologic cancers, little is known about drug-induced NDs (DI-NDs) within this population. The objective of this study was to compare the presentations and outcomes of patients with hematologic malignancies who developed MA-NDs and DI-NDs. METHODS: Cases of ND occurring between 2013 and 2023 among those with hematologic malignancies were identified from the electronic medical records of our institution. Patient characteristics, recent medication exposures, cancer mutations, and disease outcomes were reviewed. Patients were categorized with DI-ND if they were recently exposed to one of four medications known to be commonly associated with ND or were otherwise categorized with MA-ND. We report a descriptive analysis of cases of DI-ND and MA-ND. RESULTS: We identified 52 patients with ND and co-occurring hematologic malignancy including 16 cases of DI-ND (30.8%) and 36 cases of MA-ND (69.2%). The most common ND in both groups was Sweet's syndrome. Chronic underlying conditions including solid tumors, inflammatory disorders, chronic viral infection, and tobacco use were more common among those with MA-ND. Among those with DI-ND, tyrosine kinase inhibitors were the most commonly associated drugs (43.8%). The most common cancer mutation among those with DI-ND was FLT3 (43.8%), while the most common mutation among those with MA-ND was TP-53 (19.4%). Among those who had died at the time of data collection, 90.0% of those with DI-ND and 66.7% of those with MA-ND died within 1 year of ND diagnosis. CONCLUSION: Most cases of ND occurring with hematologic malignancies develop secondary to cancer rather than drug exposure. Different cancer mutations may predispose to DI-ND and MA-ND. Further research is needed to establish diagnostic criteria for DI-ND and to determine the pathogenic role of specific cancer mutations, particularly FLT3, in the development of ND.

Mortality and Autopsy Findings in Patients with Pyoderma Gangrenosum: A Multi-Institutional Series.

INTRODUCTION: Pyoderma gangrenosum (PG) is a rare ulcerative skin condition with an increased risk of mortality compared to the general population. The causes of this increased risk are not well understood. Misdiagnosis is common in PG, and many studies are limited by the inclusion of misdiagnosed cases. The goal of this study was to review autopsy findings, identify causes of death, and identify factors that may worsen outcomes among deceased patients confirmed to have PG. METHODS: Data was retrospectively reviewed from the electronic medical records at five academic hospitals. A search was conducted for deceased patients with a diagnosis of PG who had an autopsy performed between 2010 and 2020. We report a descriptive analysis of 11 patients and their clinical characteristics, causes of death, and autopsy findings. RESULTS: The average age of death was 62.9 years. Seven patients had at least one underlying condition known to be associated with PG including inflammatory bowel disease, inflammatory arthritis, or a hematologic disorder. The most common cause of death was infection (n = 6, 54.5%), followed by pulmonary embolism (n = 3, 27.3%), and myelodysplastic syndrome (n = 2, 18.2%). Six patients (54.5%) were taking systemic steroids at the time of death. CONCLUSION: The development of PG may shorten life expectancy among those with underlying conditions associated with PG, and common treatments for PG may contribute to the risk of fatal complications. Awareness of the risk of infection, thrombosis, and malignancy among those with PG is necessary for proper management. Further research is needed to explore the relationship between PG and thromboembolism.

Epidemiologic Evaluation of Retinopathy of Prematurity Severity in a Large Telemedicine Program in India Using Artificial Intelligence.

PURPOSE: Epidemiological changes in retinopathy of prematurity (ROP) depend on neonatal care, neonatal mortality, and the ability to carefully titrate and monitor oxygen. We evaluate whether an artificial intelligence (AI) algorithm for assessing ROP severity in babies can be used to evaluate changes in disease epidemiology in babies from South India over a 5-year period. DESIGN: Retrospective cohort study. PARTICIPANTS: Babies (3093) screened for ROP at neonatal care units (NCUs) across the Aravind Eye Care System (AECS) in South India. METHODS: Images and clinical data were collected as part of routine tele-ROP screening at the AECS in India over 2 time periods: August 2015 to October 2017 and March 2019 to December 2020. All babies in the original cohort were matched 1:3 by birthweight (BW) and gestational age (GA) with babies in the later cohort. We compared the proportion of eyes with moderate (type 2) or treatment-requiring (TR) ROP, and an AI-derived ROP vascular severity score (from retinal fundus images) at the initial tele-retinal screening exam for all babies in a district, VSS), in the 2 time periods. MAIN OUTCOME MEASURES: Differences in the proportions of type 2 or worse and TR-ROP cases, and VSS between time periods. RESULTS: Among BW and GA matched babies, the proportion [95% confidence interval {CI}] of babies with type 2 or worse and TR-ROP decreased from 60.9% [53.8%-67.7%] to 17.1% [14.0%-20.5%] (P < 0.001) and 16.8% [11.9%-22.7%] to 5.1% [3.4%-7.3%] (P < 0.001), over the 2 time periods. Similarly, the median [interquartile range] VSS in the population decreased from 2.9 [1.2] to 2.4 [1.8] (P < 0.001). CONCLUSIONS: In South India, over a 5-year period, the proportion of babies developing moderate to severe ROP has dropped significantly for babies at similar demographic risk, strongly suggesting improvements in primary prevention of ROP. These results suggest that AI-based assessment of ROP severity may be a useful epidemiologic tool to evaluate temporal changes in ROP epidemiology. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.