Opioid Use Disorder among Hospitalized Adults in North Carolina: Analysis from the 2000-2020 NC State Inpatient Database.

OBJECTIVES: Opioid use disorder (OUD) is characterized as a chronic condition that was first outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and now the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision. It encompasses frequent opioid usage, cravings, the development of tolerance, withdrawal symptoms upon discontinuation, unsuccessful attempts to quit or reduce use, and recurrent use even when faced with negative consequences. Both national- and state-level data show that overdose deaths associated with prescription opioids are increasing at an alarming rate. The increasing overdose deaths from illicitly manufactured fentanyl and other synthetic opioids compound this epidemic's burden. The present study sought to determine the prevalence and potential factors associated with OUD in North Carolina. METHODS: Using the State Inpatient Database, a retrospective cross-sectional study was conducted to identify OUD-related discharges between 2000 and 2020. Descriptive statistics and rates of OUD per 1000 discharges were calculated. Simple and multivariable logistic regression models were used to identify factors associated with increased odds of having an opioid use disorder diagnosis at discharge. The deviance-Pearson goodness of fit statistic was also used. Variables were identified using International Classification of Diseases, Ninth Revision, Clinical Modification, and International Classification of Diseases, Tenth Revision, Clinical Modification, codes in the discharge records. RESULTS: Of 19,370,483 hospitalizations that occurred between 2000 and 2020 in North Carolina, 483,250 were associated with OUD, a prevalence rate of 24.9 cases per 1000 discharges. The highest OUD rates were seen among adults who self-paid for their hospitalization, those with Medicaid, and those with other types of payors such as Workers' Compensation and the Indian Health Service; individuals between 25 and 54 years old; tobacco and alcohol users; Native American patients; patients located in urban areas; patients with lower household income; White patients; and female patients. OUD also was associated with increased odds of having one or more comorbid psychiatric disorders when controlling for other factors. CONCLUSIONS: Although preventive measures are crucial, including policies that discourage prescribing opioids for noncancer pain and those that target the manufacturing and distribution of synthetic opioids, providing integrated care for patients with OUD and co-occurring psychiatric and/or physical disorders is equally important. These findings suggest the need for a system-wide public health response focused on the expansion of primary prevention and treatment efforts, including crisis services, harm reduction services, and recovery programs.

Cost analysis of one-time intravenous antibiotic doses in the emergency department.

BACKGROUND: Research shows that one-time doses of intravenous (IV) antibiotics do not improve resolution of infection. Providers, however, continue to use them - especially in the emergency department. Very few studies have aimed to quantify the cost of this practice. OBJECTIVES: The primary objective was to evaluate the difference in average total cost of emergency department (ED) stay between patients who received a one-time dose of intravenous antibiotics in the ED before discharging on oral antibiotics and patients who were just discharged on oral antibiotics. Secondary objectives were to evaluate the differences in durations of stay between the two groups, as well as the differences in adverse drug effects and need for healthcare contact after discharge. METHODS: Chart review was conducted to identify patients who received and did not receive a one-time dose of IV antibiotics in the ED between April 30, 2020, and April 30, 2022. A micro-costing approach was used to determine ED-associated costs per patient. Comparisons in primary and secondary outcomes were performed using statistical inferential tests. RESULTS: A total of 102 patients were analyzed in each group. Patients who received a one-time dose of intravenous antibiotics in the emergency department before being discharged on oral antibiotics had an average length of stay of 4.55 hours, as opposed to patients who did not receive a one-time dose of intravenous antibiotics before being discharged on oral antibiotics who had an average length of stay of 2.82 hours (absolute difference: 1.73 hours, p < 0.001). One-time dosing of intravenous antibiotics in the emergency department incurred an additional cost of approximately $556 per patient, totaling to over $56,000 in our study cohort. CONCLUSION: The use of one-time intravenous antibiotics in the emergency department did not confer any additional benefits to patients. Use of one-time doses resulted in significantly reduced throughput in the emergency department and significantly increased healthcare costs.

A Modular Framework for Implicit 3D-0D Coupling in Cardiac Mechanics.

In numerical simulations of cardiac mechanics, coupling the heart to a model of the circulatory system is essential for capturing physiological cardiac behavior. A popular and efficient technique is to use an electrical circuit analogy, known as a lumped parameter network or zero-dimensional (0D) fluid model, to represent blood flow throughout the cardiovascular system. Due to the strong physical interaction between the heart and the blood circulation, developing accurate and efficient numerical coupling methods remains an active area of research. In this work, we present a modular framework for implicitly coupling three-dimensional (3D) finite element simulations of cardiac mechanics to 0D models of blood circulation. The framework is modular in that the circulation model can be modified independently of the 3D finite element solver, and vice versa. The numerical scheme builds upon a previous work that combines 3D blood flow models with 0D circulation models (3D fluid - 0D fluid). Here, we extend it to couple 3D cardiac tissue mechanics models with 0D circulation models (3D structure - 0D fluid), showing that both mathematical problems can be solved within a unified coupling scheme. The effectiveness, temporal convergence, and computational cost of the algorithm are assessed through multiple examples relevant to the cardiovascular modeling community. Importantly, in an idealized left ventricle example, we show that the coupled model yields physiological pressure-volume loops and naturally recapitulates the isovolumic contraction and relaxation phases of the cardiac cycle without any additional numerical techniques. Furthermore, we provide a new derivation of the scheme inspired by the Approximate Newton Method of Chan (1985), explaining how the proposed numerical scheme combines the stability of monolithic approaches with the modularity and flexibility of partitioned approaches.

Blocking FSH induces thermogenic adipose tissue and reduces body fat.

Menopause is associated with bone loss and enhanced visceral adiposity. A polyclonal antibody that targets the ß-subunit of the pituitary hormone follicle-stimulating hormone (Fsh) increases bone mass in mice. Here, we report that this antibody sharply reduces adipose tissue in wild-type mice, phenocopying genetic haploinsufficiency for the Fsh receptor gene Fshr. The antibody also causes profound beiging, increases cellular mitochondrial density, activates brown adipose tissue and enhances thermogenesis. These actions result from the specific binding of the antibody to the ß-subunit of Fsh to block its action. Our studies uncover opportunities for simultaneously treating obesity and osteoporosis.

Peer Network Counseling Effects on Substance Use: an Individual Participant Data Meta-Analysis Integrating Three Randomized Controlled Trials.

The current study describes an individual participant data meta-analysis (IPDMA) testing the efficacy of a peer-network counseling (PNC) intervention for preventing substance use escalation in adolescents and young adults. PNC has shown efficacy in reducing substance use among adolescents and young adults across small-scale randomized controlled trials (RCTs). Identifying expected large-scale effects and moderators is an important next step in guiding use of PNC in practice. To this end, we combine three small-scale RCTs to test PNC intervention effects on substance use change in a combined sample of 421 adolescents and young adults (50% intervention, 55% female, 69% Black/African-American, M age [SD] = 17.3 [2.2] years). Our approach combines latent change score modeling in a structural equation modeling (SEM) framework with study-level fixed effects to obtain (a) a more generalizable PNC effect than we could obtain with each constituent sample and (b) greater power and precision for individual-level moderation of treatment effects. We found that although PNC main effects on substance use outcomes (past 30-day cannabis, alcohol, tobacco, and drug use) were not significant, PNC effects were moderated by individual-level pre-intervention substance use frequency. PNC more strongly reduced drug use at the 1-month follow-up and cannabis use at the 3-month follow-up among participants who showed higher baseline use of these substances. Implications of our approach and findings for prevention researchers are discussed.

Unraveling quad fever: Severe hyperthermia after traumatic cervical spinal cord injury.

PURPOSE: There are many infectious and inflammatory causes for elevated core-body temperatures, though they rarely pass 40 â„ƒ (104 ℉). The term "quad fever" is used for extreme hyperpyrexia in the setting of acute cervical spinal cord injuries (SCIs). The traditional methods of treating hyperpyrexia are often ineffective and reported morbidity and mortality rates approach 100%. This study aims to identify the incidence of elevated temperatures in SCIs at our institution and assess the effectiveness of using a non-invasive dry water temperature management system as a treatment modality with mortality. METHODS: A retrospective analysis of acute SCI patients requiring surgical intensive care unit admission who experienced fevers ≥ 40 â„ƒ (104 ℉) were compared to patients with maximum temperatures < 40 â„ƒ. Patients ≥18 years old who sustained an acute traumatic SCI were included in this study. Patients who expired in the emergency department; had a SCI without radiologic abnormality; had neuropraxia; were admitted to any location other than the surgical intensive care unit; or had positive blood cultures were excluded. SAS 9.4 was used to conduct statistical analysis. RESULTS: Over the 9-year study period, 35 patients were admitted to the surgical intensive care unit with a verified SCI. Seven patients experienced maximum temperatures of ≥ 40 â„ƒ. Six of those patients were treated with the dry water temperature management system with an overall mortality of 57.1% in this subgroup. The mortality rate for the 28 patients who experienced a maximum temperature of ≤ 40 â„ƒ was 21.4% (p = 0.16). CONCLUSION: The diagnosis of quad fever should be considered in patients with cervical SCI in the presence of hyperthermia. In this study, there was no significant difference in mortality between quad fever patients treated with a dry water temperature management system versus SCI patients without quad fever. The early use of a dry water temperature management system appears to decrease the mortality rate of quad fever.

The physics of knocking over LEGO minifigures with time reversal focused vibrations for use in a museum exhibit.

Time reversal (TR) is a method of focusing wave energy at a point in space. The optimization of a TR demonstration is described, which knocks over one selected LEGO minifigure among other minifigures by focusing the vibrations within an aluminum plate at the target minifigure. The aim is to achieve a high repeatability of the demonstration along with reduced costs to create a museum exhibit. By comparing the minifigure's motion to the plate's motion directly beneath its feet, it is determined that a major factor inhibiting the repeatability is that the smaller vibrations before the focal event cause the minifigure to bounce repeatedly and it ends up being in the air during the main vibrational focal event, which was intended to launch the minifigure. The deconvolution TR technique is determined to be optimal in providing the demonstration repeatability. The amplitude, frequency, and plate thickness are optimized in a laboratory setting. An eddy current sensor is then used to reduce the costs, and the impact on the repeatability is determined. A description is given of the implementation of the demonstration for a museum exhibit. This demonstration illustrates the power of the focusing acoustic waves, and the principles learned by optimizing this demonstration can be applied to other real-world applications.

Health professionals' attitudes toward medications for opioid use disorder.

Background: Research has shown that medications, especially opioid agonist treatments, are an effective way to treat opioid use disorder (OUD); however, negative attitudes held by health professionals contribute to their underutilization. Methods: A 23-year review of studies that examined health professionals' attitudes toward medications for OUD (MOUD) was conducted to describe the current state of knowledge and to inform future research and interventions. Results: Studies examined attitudes toward the use of methadone, buprenorphine, and naltrexone among various types of health professionals: prescribers, non-prescribing clinicians, pharmacists, and administrators. The characteristics and findings of the included studies were reviewed and synthesized. Findings indicate that attitudes toward MOUD affect access and utilization by influencing prescribing practices, referrals, and adoption within programs. Exposure, knowledge, and treatment orientation were found to be important factors related to attitudes toward MOUD across multiple studies of various types of health professionals. Conclusions: To increase access and utilization, continued efforts are needed to increase positive attitudes toward MOUD among various types of health professionals. Findings indicate that interventions should seek to increase knowledge about MOUD and foster interprofessional communication related to MOUD, especially between prescribers and behavioral health providers.

Procalcitonin-Guided Use of Antibiotics for Lower Respiratory Tract Infection.

BACKGROUND: The effect of procalcitonin-guided use of antibiotics on treatment for suspected lower respiratory tract infection is unclear. METHODS: In 14 U.S. hospitals with high adherence to quality measures for the treatment of pneumonia, we provided guidance for clinicians about national clinical practice recommendations for the treatment of lower respiratory tract infections and the interpretation of procalcitonin assays. We then randomly assigned patients who presented to the emergency department with a suspected lower respiratory tract infection and for whom the treating physician was uncertain whether antibiotic therapy was indicated to one of two groups: the procalcitonin group, in which the treating clinicians were provided with real-time initial (and serial, if the patient was hospitalized) procalcitonin assay results and an antibiotic use guideline with graded recommendations based on four tiers of procalcitonin levels, or the usual-care group. We hypothesized that within 30 days after enrollment the total antibiotic-days would be lower - and the percentage of patients with adverse outcomes would not be more than 4.5 percentage points higher - in the procalcitonin group than in the usual-care group. RESULTS: A total of 1656 patients were included in the final analysis cohort (826 randomly assigned to the procalcitonin group and 830 to the usual-care group), of whom 782 (47.2%) were hospitalized and 984 (59.4%) received antibiotics within 30 days. The treating clinician received procalcitonin assay results for 792 of 826 patients (95.9%) in the procalcitonin group (median time from sample collection to assay result, 77 minutes) and for 18 of 830 patients (2.2%) in the usual-care group. In both groups, the procalcitonin-level tier was associated with the decision to prescribe antibiotics in the emergency department. There was no significant difference between the procalcitonin group and the usual-care group in antibiotic-days (mean, 4.2 and 4.3 days, respectively; difference, -0.05 day; 95% confidence interval [CI], -0.6 to 0.5; P=0.87) or the proportion of patients with adverse outcomes (11.7% [96 patients] and 13.1% [109 patients]; difference, -1.5 percentage points; 95% CI, -4.6 to 1.7; P<0.001 for noninferiority) within 30 days. CONCLUSIONS: The provision of procalcitonin assay results, along with instructions on their interpretation, to emergency department and hospital-based clinicians did not result in less use of antibiotics than did usual care among patients with suspected lower respiratory tract infection. (Funded by the National Institute of General Medical Sciences; ProACT ClinicalTrials.gov number, NCT02130986 .).

Reducing Risk for Adolescent Substance Misuse with Text-Delivered Counseling to Adolescents and Parents.

Background: Text-delivered prevention programs provide unique opportunities to deliver substance use prevention interventions to at-risk populations. Methods: A pilot randomized controlled trial was conducted to test the feasibility, acceptability, and preliminary efficacy of a 4-week, automated personalized text-messaging prevention program, designed to reduce risk factors and increase protective factors associated with adolescent substance use and misuse. Sixty-nine adolescents were recruited from a Federally Qualified Health Care clinic and randomized to a text-delivered intervention, or a wait-list control condition. Simultaneously, fifty-two parents of adolescent participants were enrolled into a parenting skills text-delivered intervention. Participants completed a baseline assessment and three follow-up surveys over three-months. Adolescent saliva specimens for drug testing were collected. Results: All intervention-allocated adolescents implemented at least one of the text-based counseling recommendations and 79% indicated that they found the texts helpful. Significant intervention effects were found on risk and protective factors for substance misuse. Adolescents in the intervention group reported reduced depression symptoms (d = -.63) and anxiety symptoms (d = -.57). Relative to controls, adolescents in the intervention group maintained a higher quality of parental relationship (d = .41) and parenting skills (d = .51), suggesting a prophylactic effect. Marginal decrease in the odds of positive drug tests were found for youth in intervention group (77.1% decrease, p = 0.07) but not with controls (54.3% decrease, p = 0.42,). Conclusions: Results provide preliminary evidence in the feasibility, acceptability, and efficacy of targeting risk and protective factors that are implicated in substance use via text-delivered interventions for high-risk populations.

Reducing Catheter-Associated Urinary Tract Infection: The Impact of Routine Screening in the Geriatric Hip Fracture Population.

BACKGROUND: Catheter-associated urinary tract infection (CAUTI) is a noted complication among geriatric hip fracture patients. This complication results in negative outcomes for both the patients and the institution providing care. Screening measures to identify predisposing factors, with early diagnosis and treatment of urinary tract infection (UTI) present on admission, may lead to reduced rates of CAUTI. OBJECTIVE: The goals of this study were to determine the prevalence of UTI on admission among geriatric hip fracture patients and whether routine screening for UTI or predisposing factors at presentation resulted in reduced rates of CAUTI. METHODS: A retrospective observational study of geriatric hip fracture patients from January 2017 to December 2018 at a Level I trauma center was performed. Rates of UTI on admission and CAUTI were calculated using routine admission urinalysis. RESULTS: Of the 183 patients in the sample, 36.1% had UTI on admission and 4.4% of patients developed CAUTI. There were no significant differences in patient demographics, comorbidities, and complications between those with UTI on admission and those without. CONCLUSIONS: Urinary tract infection on admission may be present among a large portion of geriatric hip fracture patients, leading to increased rates of CAUTI. Routine screening for UTI and its predisposing factors at admission can identify these patients earlier and lead to earlier treatments and prevention of CAUTI.

Risk of type 2 diabetes mellitus by antimuscarinic agents among adult females receiving care in the military health system.

PURPOSE: To explore patterns of antimuscarinic medication as a risk factor for type 2 diabetes mellitus (T2DM). METHODS: This is a retrospective cohort study of females 18 years or older within the Military Health System from 2006 to 2016. Administrative and claims data were used to select patients who initiated therapy with tolterodine, fesoterodine, oxybutynin, darifenacin, solifenacin, or trospium. Patients with no documented history of T2DM were followed for the occurrence of T2DM, the end of the study or loss of eligibility. Rates of T2DM were calculated for the overall population, by duration of therapy and by individual drugs. Crude and adjusted Cox proportional hazards were calculated to assess differences by duration of use and specific muscarinic antagonist. RESULTS: Over 2.6 million antimuscarinic prescriptions were dispensed to 241 829 females (mean age/SD, 62 ± 18 years). Patients exposed to M3 selective antagonists had highest risk of developing T2DM compared to those exposed to nonselective antagonists. Using oxybutynin, a nonselective antagonist as a comparator, adjusted rate ratios of T2DM were 57% (HR 1.57, 95%CI 1.48-1.67) and 29% (HR 1.29, 95%CI 1.24-1.35) significantly higher for darifenacin and solifenacin, respectively (both M3 selective). CONCLUSIONS: We found exposure to M3 selective antagonists darifenacin and solifenacin had the highest risk of developing T2DM compared to nonselective antagonist oxybutynin. This is supported by well described physiologic mechanisms and may allow for more informed prescribing decisions, particularly if minimizing risk of T2DM is a priority.

Disparate levels of beta-catenin activity determine nephron progenitor cell fate.

Formation of a functional kidney depends on the balance between renewal and differentiation of nephron progenitors. Failure to sustain this balance can lead to kidney failure or stem cell tumors. For nearly 60 years, we have known that signals from an epithelial structure known as the ureteric bud were essential for maintaining this balance. More recently it was discovered that one molecule, Wnt9b, was necessary for both renewal and differentiation of the nephron progenitor cells. How one ligand signaling through one transcription factor promoted two seemingly contradictory cellular processes was unclear. In this study, we show that Wnt9b/beta-catenin signaling alone is sufficient to promote both renewal and differentiation. Moreover, we show that discrete levels of beta-catenin can promote these two disparate fates, with low levels fostering progenitor renewal and high levels driving differentiation. These results provide insight into how Wnt9b regulates distinct target genes that balance nephron progenitor renewal and differentiation.

Biotransformation of organic acids to their corresponding alcohols by Thermoanaerobacter pseudoethanolicus.

Higher order alcohols, such as 1-butanol and 1-hexanol, have a large number of applications but are currently prepared from non-renewable feedstocks. Here, the ability of Thermoanaerobacter pseudoethanolicus to reduce short-chain fatty acids to their corresponding alcohols using reducing potential generated by glucose catabolism with yields between 21.0 and 61.0%. 13C-labelled acetate, 1-propionate and 1-butyrate demonstrates that exogenously added fatty acids are indeed reduced to their corresponding alcohols. This mode of producing primary alcohols from fatty acids using a thermophilic anaerobe opens the door for the production of such alcohols from low-value materials using an inexpensive source of reducing potential.

Mechanistic target of rapamycin: integrating growth factor and nutrient signaling in the collecting duct.

The renal collecting duct and other postmacula densa sites are the primary tubular regions for fine-tuning of electrolyte homeostasis in the body. A role for the mechanistic target of rapamycin (mTOR), a serine-threonine kinase, has recently been appreciated in this regulation. mTOR exists in two distinct multiprotein functional complexes, i.e., mTORC1 and mTORC2. Upregulation of mTORC1, by growth factors and amino acids, is associated with cell cycle regulation and hypertrophic changes. In contrast, mTORC2 has been demonstrated to have a role in regulating Na+ and K+ reabsorptive processes, including those downstream of insulin and serum- and glucocorticoid-regulated kinase (SGK). In addition, mTORC2 can upregulate mTORC1. A number of elegant in vitro and in vivo studies using cell systems and genetically modified mice have revealed mechanisms underlying activation of the epithelial Na+ channel (ENaC) and the renal outer medullary K+ channel (ROMK) by mTORC2. Overall, mTOR in its systematic integration of phosphorylative signaling facilitates the delicate balance of whole body electrolyte homeostasis in the face of changes in metabolic status. Thus, inappropriate regulation of renal mTOR has the potential to result in electrolyte disturbances, such as acidosis/alkalosis, hyponatremia, and hypertension. The goal of this minireview is to highlight the physiological role of mTOR in its complexes in regulating electrolyte homeostasis in the aldosterone-sensitive distal nephron.

p53 Enables metabolic fitness and self-renewal of nephron progenitor cells.

Contrary to its classic role in restraining cell proliferation, we demonstrate here a divergent function of p53 in the maintenance of self-renewal of the nephron progenitor pool in the embryonic mouse kidney. Nephron endowment is regulated by progenitor availability and differentiation potential. Conditional deletion of p53 in nephron progenitor cells (Six2Cre(+);p53(fl/fl)) induces progressive depletion of Cited1(+)/Six2(+) self-renewing progenitors and loss of cap mesenchyme (CM) integrity. The Six2(p53-null) CM is disorganized, with interspersed stromal cells and an absence of a distinct CM-epithelia and CM-stroma interface. Impaired cell adhesion and epithelialization are indicated by decreased E-cadherin and NCAM expression and by ineffective differentiation in response to Wnt induction. The Six2Cre(+);p53(fl/fl) cap has 30% fewer Six2(GFP(+)) cells. Apoptotic index is unchanged, whereas proliferation index is significantly reduced in accordance with cell cycle analysis showing disproportionately fewer Six2Cre(+);p53(fl/fl) cells in the S and G2/M phases compared with Six2Cre(+);p53(+/+) cells. Mutant kidneys are hypoplastic with fewer generations of nascent nephrons. A significant increase in mean arterial pressure is observed in early adulthood in both germline and conditional Six2(p53-null) mice, linking p53-mediated defects in kidney development to hypertension. RNA-Seq analyses of FACS-isolated wild-type and Six2(GFP(+)) CM cells revealed that the top downregulated genes in Six2Cre(+);p53(fl/fl) CM belong to glucose metabolism and adhesion and/or migration pathways. Mutant cells exhibit a ∼ 50% decrease in ATP levels and a 30% decrease in levels of reactive oxygen species, indicating energy metabolism dysfunction. In summary, our data indicate a novel role for p53 in enabling the metabolic fitness and self-renewal of nephron progenitors.

LectureKeepr: A novel approach to studying in the adaptive curriculum.

As medical students search for ways to squeeze more hours of learning into their day, many have turned to technology for quick and efficient ways to study. Most commonly this includes based apps for purchase that involve visual tasks, mental review and repetition. Tasks involve flashcard creation, answering multiple choice questions (MCQs) and schedule planning. They typically require students to visually interact with a computer or smartphone screen. Alternatively, auditory apps may not only offer the benefit of enhanced learning through review and repetition, but also address convenience, portability, and metacognitive development without physical and temporal requirements of visual presentation. Auditory learning is eyes and "hands-free" allowing the learner to contiguously engage in other activities such as physical exercise, traveling, eating, etc. In this randomized, case-comparison study, half of the students were exposed to audio lecture content before class using a mobile application called LectureKeepr (LK) and half were exposed to lecture content before class via written material prepared by the professor. Pre- and post-MCQ quizzes were used to measure differences between groups in knowledge improvement. In addition, student perceptions of the auditory learning experience were assessed by an on-line survey. ANOVA with repeated measures revealed that students in the LK intervention group performed better on the postquiz than the students in the written materials group.

Next-Generation Probiotics Targeting Clostridium difficile through Precursor-Directed Antimicrobial Biosynthesis.

Integration of antibiotic and probiotic therapy has the potential to lessen the public health burden of antimicrobial-associated diseases. Clostridium difficile infection (CDI) represents an important example where the rational design of next-generation probiotics is being actively pursued to prevent disease recurrence. Because intrinsic resistance to clinically relevant antibiotics used to treat CDI (vancomycin, metronidazole, and fidaxomicin) is a desired trait in such probiotic species, we screened several bacteria and identified Lactobacillus reuteri to be a promising candidate for adjunct therapy. Human-derived L. reuteri bacteria convert glycerol to the broad-spectrum antimicrobial compound reuterin. When supplemented with glycerol, strains carrying the pocR gene locus were potent reuterin producers, with L. reuteri 17938 inhibiting C. difficile growth at a level on par with the level of growth inhibition by vancomycin. Targeted pocR mutations and complementation studies identified reuterin to be the precursor-induced antimicrobial agent. Pathophysiological relevance was demonstrated when the codelivery of L. reuteri with glycerol was effective against C. difficile colonization in complex human fecal microbial communities, whereas treatment with either glycerol or L. reuteri alone was ineffective. A global unbiased microbiome and metabolomics analysis independently confirmed that glycerol precursor delivery with L. reuteri elicited changes in the composition and function of the human microbial community that preferentially targets C. difficile outgrowth and toxicity, a finding consistent with glycerol fermentation and reuterin production. Antimicrobial resistance has thus been successfully exploited in the natural design of human microbiome evasion of C. difficile, and this method may provide a prototypic precursor-directed probiotic approach. Antibiotic resistance and substrate bioavailability may therefore represent critical new determinants of probiotic efficacy in clinical trials.

FOXD1 promotes nephron progenitor differentiation by repressing decorin in the embryonic kidney.

Forkhead transcription factors are essential for diverse processes in early embryonic development and organogenesis. Foxd1 is required during kidney development and its inactivation results in failure of nephron progenitor cell differentiation. Foxd1 is expressed in interstitial cells adjacent to nephron progenitor cells, suggesting an essential role for the progenitor cell niche in nephrogenesis. To better understand how cortical interstitial cells in general, and FOXD1 in particular, influence the progenitor cell niche, we examined the differentiation states of two progenitor cell subtypes in Foxd1(-/-) tissue. We found that although nephron progenitor cells are retained in a primitive CITED1-expressing compartment, cortical interstitial cells prematurely differentiate. To identify pathways regulated by FOXD1, we screened for target genes by comparison of Foxd1 null and wild-type tissues. We found that the gene encoding the small leucine-rich proteoglycan decorin (DCN) is repressed by FOXD1 in cortical interstitial cells, and we show that compound genetic inactivation of Dcn partially rescues the failure of progenitor cell differentiation in the Foxd1 null. We demonstrate that DCN antagonizes BMP/SMAD signaling, which is required for the transition of CITED1-expressing nephron progenitor cells to a state that is primed for WNT-induced epithelial differentiation. On the basis of these studies, we propose a mechanism for progenitor cell retention in the Foxd1 null in which misexpressed DCN produced by prematurely differentiated interstitial cells accumulates in the extracellular matrix, inhibiting BMP7-mediated transition of nephron progenitor cells to a compartment in which they can respond to epithelial induction signals.

Structural Basis of Native CXCL7 Monomer Binding to CXCR2 Receptor N-Domain and Glycosaminoglycan Heparin.

CXCL7, a chemokine highly expressed in platelets, orchestrates neutrophil recruitment during thrombosis and related pathophysiological processes by interacting with CXCR2 receptor and sulfated glycosaminoglycans (GAG). CXCL7 exists as monomers and dimers, and dimerization (~50 µM) and CXCR2 binding (~10 nM) constants indicate that CXCL7 is a potent agonist as a monomer. Currently, nothing is known regarding the structural basis by which receptor and GAG interactions mediate CXCL7 function. Using solution nuclear magnetic resonance (NMR) spectroscopy, we characterized the binding of CXCL7 monomer to the CXCR2 N-terminal domain (CXCR2Nd) that constitutes a critical docking site and to GAG heparin. We found that CXCR2Nd binds a hydrophobic groove and that ionic interactions also play a role in mediating binding. Heparin binds a set of contiguous basic residues indicating a prominent role for ionic interactions. Modeling studies reveal that the binding interface is dynamic and that GAG adopts different binding geometries. Most importantly, several residues involved in GAG binding are also involved in receptor interactions, suggesting that GAG-bound monomer cannot activate the receptor. Further, this is the first study that describes the structural basis of receptor and GAG interactions of a native monomer of the neutrophil-activating chemokine family.