CryoEM structures of the human CLC-2 voltage-gated chloride channel reveal a ball-and-chain gating mechanism.

CLC-2 is a voltage-gated chloride channel that contributes to electrical excitability and ion homeostasis in many different tissues. Among the nine mammalian CLC homologs, CLC-2 is uniquely activated by hyperpolarization, rather than depolarization, of the plasma membrane. The molecular basis for the divergence in polarity of voltage gating among closely related homologs has been a long-standing mystery, in part because few CLC channel structures are available. Here, we report cryoEM structures of human CLC-2 at 2.46 - 2.76 Å, in the presence and absence of the selective inhibitor AK-42. AK-42 binds within the extracellular entryway of the Cl--permeation pathway, occupying a pocket previously proposed through computational docking studies. In the apo structure, we observed two distinct conformations involving rotation of one of the cytoplasmic C-terminal domains (CTDs). In the absence of CTD rotation, an intracellular N-terminal 15-residue hairpin peptide nestles against the TM domain to physically occlude the Cl--permeation pathway. This peptide is highly conserved among species variants of CLC-2 but is not present in other CLC homologs. Previous studies suggested that the N-terminal domain of CLC-2 influences channel properties via a "ball-and-chain" gating mechanism, but conflicting data cast doubt on such a mechanism, and thus the structure of the N-terminal domain and its interaction with the channel has been uncertain. Through electrophysiological studies of an N-terminal deletion mutant lacking the 15-residue hairpin peptide, we support a model in which the N-terminal hairpin of CLC-2 stabilizes a closed state of the channel by blocking the cytoplasmic Cl--permeation pathway.

Substance Use Among Patients With Incident Crohn's Disease in the United States, 2010 to 2019: A Medicaid Observational Study.

BACKGROUND AND AIMS: Substance use among persons with Crohn's disease (CD) is associated with symptomatic exacerbation and poorer quality of life. However, data on the prevalence of substance use among individuals with CD are limited. Therefore, our study aimed to estimate the burden of alcohol and drug use among individuals with incident CD in the United States. We also assessed the associations between CD-related interventions and substance use after CD diagnosis. METHODS: Our retrospective cohort study of the national Medicaid databases from 2010 to 2019 identified participants with newly diagnosed CD and defined substance use (ie, alcohol, opioids, cocaine, amphetamine, and cannabis) using diagnosis codes. Multivariable logistic regression models assessed the associations between CD-related interventions and substance use after CD diagnosis. RESULTS: Overall, 16.3% of Medicaid enrollees with incident CD had substance ever-use, most commonly alcohol or opioids (each 8.0%). Any substance use saw an absolute decrease of 3.8% after CD diagnosis, but changes were less than 1% in either direction for each substance. CD-related hospitalization was associated with increased alcohol or opioid use post-CD diagnosis. Surgery was associated with lower use post-CD of opioids but not alcohol. CD medications (except steroids) were generally associated with decreased post-CD alcohol or opioid use. CONCLUSION: Among Medicaid enrollees with incident CD, alcohol and opioid use were more frequent than previously published estimates for the general US population (6% and 4%, respectively, in 2019). Consequently, medical communities must be more aware of substance use by patients with CD to provide quality patient-centered care.

CryoEM structures of the human CLC-2 voltage gated chloride channel reveal a ball and chain gating mechanism.

CLC-2 is a voltage-gated chloride channel that contributes to electrical excitability and ion homeostasis in many different mammalian tissues and cell types. Among the nine mammalian CLC homologs, CLC-2 is uniquely activated by hyperpolarization, rather than depolarization, of the plasma membrane. The molecular basis for the divergence in polarity of voltage gating mechanisms among closely related CLC homologs has been a long-standing mystery, in part because few CLC channel structures are available, and those that exist exhibit high conformational similarity. Here, we report cryoEM structures of human CLC-2 at 2.46 - 2.76 Å, in the presence and absence of the potent and selective inhibitor AK-42. AK-42 binds within the extracellular entryway of the Cl--permeation pathway, occupying a pocket previously proposed through computational docking studies. In the apo structure, we observed two distinct apo conformations of CLC-2 involving rotation of one of the cytoplasmic C-terminal domains (CTDs). In the absence of CTD rotation, an intracellular N-terminal 15-residue hairpin peptide nestles against the TM domain to physically occlude the Cl--permeation pathway from the intracellular side. This peptide is highly conserved among species variants of CLC-2 but is not present in any other CLC homologs. Previous studies suggested that the N-terminal domain of CLC-2 influences channel properties via a "ball-and-chain" gating mechanism, but conflicting data cast doubt on such a mechanism, and thus the structure of the N-terminal domain and its interaction with the channel has been uncertain. Through electrophysiological studies of an N-terminal deletion mutant lacking the 15-residue hairpin peptide, we show that loss of this short sequence increases the magnitude and decreases the rectification of CLC-2 currents expressed in mammalian cells. Furthermore, we show that with repetitive hyperpolarization WT CLC-2 currents increase in resemblance to the hairpin-deleted CLC-2 currents. These functional results combined with our structural data support a model in which the N-terminal hairpin of CLC-2 stabilizes a closed state of the channel by blocking the cytoplasmic Cl--permeation pathway.

Data Science as a Core Competency in Undergraduate Medical Education in the Age of Artificial Intelligence in Health Care.

The increasingly sophisticated and rapidly evolving application of artificial intelligence in medicine is transforming how health care is delivered, highlighting a need for current and future physicians to develop basic competency in the data science that underlies this topic. Medical educators must consider how to incorporate central concepts in data science into their core curricula to train physicians of the future. Similar to how the advent of diagnostic imaging required the physician to understand, interpret, and explain the relevant results to patients, physicians of the future should be able to explain to patients the benefits and limitations of management plans guided by artificial intelligence. We outline major content domains and associated learning outcomes in data science applicable to medical student curricula, suggest ways to incorporate these themes into existing curricula, and note potential implementation barriers and solutions to optimize the integration of this content.

Tobacco use in Crohn's disease patients and association with disease outcomes in the United States Medicaid population, 2010-2019.

Background and Aim: To identify demographic factors associated with tobacco use in Crohn's disease (CD) patients in the US Medicaid population and examine how tobacco use affects disease outcomes. Methods: We included Medicaid-eligible patients who had ≥1 ICD code for CD, and 1 year of eligibility before and after the initial encounter. We used ICD codes to identify tobacco use with respect to the time of diagnosis and used logistic regression to identify the association between age, sex, and race with tobacco use at any point before diagnosis and after diagnosis, and determine the association of tobacco use before and after diagnosis on disease outcomes. Results: We identified 98 176 eligible patients; 74.5% had no documented use of tobacco and 25.5% used tobacco at some point; 21.1% had used tobacco before their CD diagnosis and 11.8% had used tobacco after diagnosis. The population that used tobacco had a higher proportion of women, those who were White, non-Hispanic, and those in their middle ages (21-60) than the group that did not use tobacco. Tobacco use before diagnosis resulted in higher risk of hospitalization and surgery (OR: 1.85 and 1.36, respectively). Conclusion: Within the CD Medicaid population, tobacco use is more common in women than men, which differs from the general population, which is possibly a result of using diagnostic codes rather than survey data. Smoking cessation efforts should especially be directed at younger people who are at risk for CD, due to increased risk for more adverse outcomes among those who use tobacco before diagnosis.

Human-Centered Design of a Clinical Decision Support for Anemia Screening in Children with Inflammatory Bowel Disease.

BACKGROUND: Inflammatory bowel disease (IBD) commonly leads to iron deficiency anemia (IDA). Rates of screening and treatment of IDA are often low. A clinical decision support system (CDSS) embedded in an electronic health record could improve adherence to evidence-based care. Rates of CDSS adoption are often low due to poor usability and fit with work processes. One solution is to use human-centered design (HCD), which designs CDSS based on identified user needs and context of use and evaluates prototypes for usefulness and usability. OBJECTIVES: this study aimed to use HCD to design a CDSS tool called the IBD Anemia Diagnosis Tool, IADx. METHODS: Interviews with IBD practitioners informed creation of a process map of anemia care that was used by an interdisciplinary team that used HCD principles to create a prototype CDSS. The prototype was iteratively tested with "Think Aloud" usability evaluation with clinicians as well as semi-structured interviews, a survey, and observations. Feedback was coded and informed redesign. RESULTS: Process mapping showed that IADx should function at in-person encounters and asynchronous laboratory review. Clinicians desired full automation of clinical information acquisition such as laboratory trends and analysis such as calculation of iron deficit, less automation of clinical decision selection such as laboratory ordering, and no automation of action implementation such as signing medication orders. Providers preferred an interruptive alert over a noninterruptive reminder. CONCLUSION: Providers preferred an interruptive alert, perhaps due to the low likelihood of noticing a noninterruptive advisory. High levels of desire for automation of information acquisition and analysis with less automation of decision selection and action may be generalizable to other CDSSs designed for chronic disease management. This underlines the ways in which CDSSs have the potential to augment rather than replace provider cognitive work.

Implementation and cost validation of a real-time benefit tool.

OBJECTIVES: To assess the accuracy of a real-time benefit tool (RTBT) that is compliant with the standards of the National Council for Prescription Drug Programs (NCPDP) in a large academic medical center. STUDY DESIGN: Observational study of electronic health records and pharmacy records from July 14, 2019, through January 14, 2020, across all ambulatory clinics and outpatient pharmacies in the health system. METHODS: Main assessments included (1) demographic characteristics of patients in whom the RTBT was used and those in whom it was not used, (2) types of changes most frequently made to medication orders upon reviewing the RTBT, and (3) comparison of the out-of-pocket costs for prescriptions vs the RTBT-generated estimates. RESULTS: The most common modifications made to prescriptions due to RTBT use were changes in days' supply (44%) and the quantity of medication (69%). In more than 98% of prescription orders, patients' out-of-pocket costs were either equivalent to or lower than the estimates generated by the RTBT. CONCLUSIONS: Current standards established by NCPDP yield accurate patient out-of-pocket estimates and could serve as a national standard for all Part D sponsors.

Boat encounter with the 2019 Java bioluminescent milky sea: Views from on-deck confirm satellite detection.

"Milky seas" are massive swaths of uniformly and steadily glowing ocean seen at night. The phenomenon is thought to be caused by luminous bacteria, but details of milky sea composition, structure, cause, and implications in nature remain largely uncertain. Between late July and early September 2019, specialized low-light satellite sensors detected a possible bioluminescent milky sea south of Java, Indonesia, spanning >100,000 km2. Upon learning of these findings, crew members of the yacht Ganesha reached out to confirm and share details of their personal encounter with this same event. Here, we document Ganesha's experience as recalled by the crew, compare their course to satellite data, and assess their photography of this milky sea.

Honing in on bioluminescent milky seas from space.

Milky seas are a rare form of marine bioluminescence where the nocturnal ocean surface produces a widespread, uniform and steady whitish glow. Mariners have compared their appearance to a daylit snowfield that extends to all horizons. Encountered most often in remote waters of the northwest Indian Ocean and the Maritime Continent, milky seas have eluded rigorous scientific inquiry, and thus little is known about their composition, formation mechanism, and role within the marine ecosystem. The Day/Night Band (DNB), a new-generation spaceborne low-light imager, holds potential to detect milky seas, but the capability has yet to be demonstrated. Here, we show initial examples of DNB-detected milky seas based on a multi-year (2012-2021) search. The massive bodies of glowing ocean, sometimes exceeding 100,000 km2 in size, persist for days to weeks, drift within doldrums amidst the prevailing sea surface currents, and align with narrow ranges of sea surface temperature and biomass in a way that suggests water mass isolation. These findings show how spaceborne assets can now help guide research vessels toward active milky seas to learn more about them.

The 21st Century CURES Act in Pediatric Gastroenterology: Problems, Solutions, and Preliminary Guidance.

ABSTRACT: The information blocking (IB) prohibition component of the 21st Century CURES Act (21CCA) comes into effect April 5, 2021, which gives patients and their families near-instant access to almost all clinical notes, lab results, and health data. Exceptions to IB prohibition include risk of harm and patient privacy, but violations can be punished by a fine of up to $1,000,000.00. A committee of pediatric gastroenterologists reviewed the 21CCA regulation and compared local practice policies. Pediatric practitioners need to understand how age will affect local information release policies and to know which note types are released, paying special consideration to trainee notes and confidential information. Extraneous detail should be removed from notes, emotional labeling be avoided, and objective statements be made when referring to the care of other providers. Awareness of the 21CCA provides pediatric gastroenterologists with the opportunity to adapt their medical documentation practices to accommodate the new law.

Telemedicine Expansion in Pediatric Gastroenterology in Response to COVID-19: Early Results of an International Physician Survey.

The COVID-19 pandemic triggered an unprecedented expansion of telemedicine, leading to development of new workflows. We conducted a survey of telemedicine practice among pediatric gastroenterology practitioners on March 26, 2020. Responses were coded and analyzed. The survey garnered 33 responses. Most centers were 3 weeks into the implementation. The most commonly used telemedicine software was Zoom followed by FaceTime, telephone, and Epic software. Provider education was through online meetings, webinars, and tip sheets. Patient education was by nonclinical staff at the time of visit scheduling or tip sheets. A major barrier was the need for patients to enroll in an electronic portal. Two thirds of practices offered telemedicine to both new and return patients. Most sites billed based on time. This represents a record of the very early response of the pediatric gastroenterology community to the COVID-19 telemedicine expansion and can inform follow-up studies.

Evaluation of a Training Program to Improve Organizational Capacity for Health Systems Analytics.

OBJECTIVE: The Leadership in Analytics and Data Science (LEADS) course was evaluated for effectiveness. LEADS was a 6-month program for working biomedical and health informatics (BMHI) professionals designed to improve analytics skills, knowledge of enterprise applications, data stewardship, and to foster an analytics community of practice through lectures, hands-on skill building workshops, networking events, and small group projects. METHODS: The effectiveness of the LEADS course was evaluated using the Kirkpatrick Model by assessing pre- and postcourse knowledge, analytics capabilities, goals, practice, class lecture reaction, and change in the size of participant professional networks. Differences in pre- and postcourse responses were analyzed with a Wilcoxon signed rank test to determine significance, and effect sizes were computed using a z-statistic. RESULTS: Twenty-nine students completed the course with 96% of respondents reporting that they were "very" or "extremely" likely to recommend the course. Participants reported improvement in several analytics capabilities including Epic data warehousing (p = 0.017), institutional review board policy (p = 0.005), and data stewardship (p = 0.007). Changes in practice patterns mirrored those in self-reported capability. On average, the participant professional network doubled. CONCLUSION: LEADS was the first course targeted to working BMHI professional at a large academic medical center to have a formal effectiveness evaluation be published in the literature. The course achieved the goals of expansion of BMHI knowledge, skills, and professional networks. The LEADS course provides a template for continuing education of working BMHI professionals.

Anemia Screening, Prevalence, and Treatment in Pediatric Inflammatory Bowel Disease in the United States, 2010-2014.

PURPOSE: We examined the prevalence of anemia, annual screening for anemia, and treatment of anemia with iron among children with inflammatory bowel disease (IBD). METHODS: A retrospective study of U.S. pediatric patients with IBD was performed in the MarketScan commercial claims database from 2010-2014. Children (ages 1-21) with at least two inpatient or outpatient encounters for IBD who had available lab and pharmacy data were included in the cohort. Anemia was defined using World Health Organization criteria. We used logistic regression to determine differences in screening, incident anemia, and treatment based on age at first IBD encounter and sex. RESULTS: The cohort (n=2,446) included 1,560 Crohn's disease (CD) and 886 ulcerative colitis (UC). Approximately, 85% of CD and 81% of UC were screened for anemia. Among those screened, 51% with CD and 43% with UC had anemia. Only 24% of anemia patients with CD and 20% with UC were tested for iron deficiency; 85% were iron deficient. Intravenous (IV) iron was used to treat 4% of CD and 4% UC patients overall and 8% of those with anemia. CONCLUSION: At least 80% of children with IBD were screened for anemia, although most did not receive follow-up tests for iron deficiency. The 43%-50% prevalence of anemia was consistent with prior studies. Under-treatment with IV iron points to a potential target for quality improvement.

Epibiotic pressure contributes to biofouling invader success.

Reduced competition is a frequent explanation for the success of many introduced species. In benthic marine biofouling communities, space limitation leads to high rates of overgrowth competition. Some species can utilise other living organisms as substrate (epibiosis), proffering a competitive advantage for the epibiont. Additionally, some species can prevent or reduce epibiotic settlement on their surfaces and avoid being basibionts. To test whether epibiotic pressure differs between native and introduced species, we undertook ex situ experiments comparing bryozoan larval settlement to determine if introduced species demonstrate a greater propensity to settle as epibionts, and a reduced propensity to be basibionts, than native species. Here we report that introduced species opportunistically settle on any space (bare, native, or introduced), whereas native species exhibit a strong tendency to settle on and near other natives, but avoid settling on or near introduced basibionts. In addition, larvae of native species experience greater larval wastage (mortality) than introduced species, both in the presence and absence of living substrates. Introduced species' ability to settle on natives as epibionts, and in turn avoid epibiosis as basibionts, combined with significantly enhanced native larval wastage, provides a comprehensive suite of competitive advantages contributing to the invasion success of these biofouling species.

ER Chaperone BiP/GRP78 Is Required for Myelinating Cell Survival and Provides Protection during Experimental Autoimmune Encephalomyelitis.

Myelinating cells synthesize large amounts of membrane protein through the secretory pathway, which makes these cells particularly sensitive to perturbations of the endoplasmic reticulum (ER). Ig binding protein (BiP), also known as glucose-regulated protein 78 (GRP78), is a critical ER chaperone that also plays a pivotal role in controlling the cellular response to ER stress. To examine the potential importance of BiP to myelinating cells, we used a conditional knock-out approach to BiP gene inactivation in oligodendrocytes during development, in adulthood, and in response to experimental autoimmune encephalomyelitis (EAE), an animal model of the inflammatory demyelinating disorder multiple sclerosis (MS). During development, mice lacking functional BiP gene expression in oligodendrocytes developed tremors and ataxia and died before reaching maturity. When BiP gene inactivation in oligodendrocytes was initiated in adulthood, the mice displayed severe neurological symptoms including tremors and hind-limb paralysis. The inactivation of BiP in oligodendrocytes during development or in adulthood resulted in oligodendrocyte loss and corresponding severe myelin abnormalities. Mice heterozygous for the oligodendrocyte-specific inactivation of BiP, which were phenotypically normal without evidence of neuropathology, displayed an exacerbated response to EAE that correlated with an increased loss of oligodendrocytes. Furthermore, mice in which the BiP gene was specifically inactivated in developing Schwann cells displayed tremor that progressed to hindlimb paralysis, which correlated with diminished numbers of myelinating Schwann cells and severe PNS hypomyelination. These studies demonstrate that BiP is critical for myelinating cell survival and contributes to the protective response of oligodendrocyte against inflammatory demyelination.