Collapse of late endosomal pH elicits a rapid Rab7 response via V-ATPase and RILP

Endosomal-lysosomal trafficking is accompanied by the acidification of endosomal compartments by the H+-V-ATPase to reach low lysosomal pH. Disruption of proper pH impairs lysosomal function and the balance of protein synthesis and degradation (proteostasis). We used the small dipeptide LLOMe, which is known to permeabilize lysosomal membranes, and find that LLOMe also impacts late endosomes (LEs) by neutralizing their pH without causing membrane permeabilization. We show that LLOMe leads to hyper-activation of Rab7 and disruption of tubulation and mannose-6-phosphate receptor (CI-M6PR) recycling on pH-neutralized LEs. Either pH neutralization (NH4Cl) or Rab7 hyper-active mutants alone can phenocopy the alterations in tubulation and CI-M6PR trafficking. Mechanistically, pH neutralization increases the assembly of the V1G1 subunit of the V-ATPase on endosomal membranes, which stabilizes GTP-bound Rab7 via RILP, a known interactor of Rab7 and V1G1. We propose a novel pathway by which V-ATPase and RILP modulate LE pH and Rab7 activation in concert. This pathway might broadly contribute to pH control during physiologic endosomal maturation or starvation and during pathologic pH neutralization, which occurs via lysosomotropic compounds or in disease states.

A Practical Guide to QI Data Analysis: Run and Statistical Process Control Charts

Data analysis utilizing run charts and statistical process control (SPC) charts is a mainstay of quality improvement (QI) work. These types of time series analyses allow QI teams to evaluate patterns in data that may not be apparent with pre- and postintervention analysis. A run chart is most useful at the onset of a project when data points may be limited; points can be added prospectively to monitor for changes. An SPC chart is needed to determine if the system is "out of control," indicating an instance of special cause variation, and is recommended for more robust data analysis. These charts are valuable tools in identifying patterns of change, but cannot indicate what caused the change. QI teams can further investigate significant patterns to identify the impact of interventions and promote continued change or sustainability. In this article, we will provide a practical guide to the basics of run and SPC charts, including how to create and interpret them. The reader can use the supplemental data tables to gain the skills needed to build their own charts with readily available software. Finally, we will review more specialized software options that can assist in creation of run and SPC charts.

Geographic Variation in Acute Pediatric Mental Health Utilization

OBJECTIVE

To identify locations with higher need for acute pediatric mental health (MH) interventions or services and describe these communities' socio-demographic characteristics.

METHODS

This single-center retrospective study included patients 5 to 18 years old with an emergency department (ED) or hospital admission between 2017 and 2019 for a primary known MH diagnosis or symptoms. We extracted visit data from the electronic medical record, mapped patients to their home census tract, calculated normalized visit rates by census tract, and performed spatial analysis to identify nonrandom geographic clusters and outliers of high utilization. Census tract utilization rates were stratified into quartiles, and socioeconomic and demographic characteristics obtained from the US Census Bureau were compared using analysis of variance, chi-square tests, and multivariable analysis.

RESULTS

There were 10,866 qualifying visits across 617 census tracts. ED and hospital admission rates ranged from 2.7 to 428.6 per 1000 children. High utilization clusters localized to neighborhoods with lower socioeconomic status (p < .05). Southern regions with high utilizers were more likely to have fewer children per neighborhood, higher rates of teen births, and lower socioeconomic status. Multivariate analysis showed regions with high utilizers had fewer children per neighborhood, lower median household income, and more families that lacked computer access.

CONCLUSION

ED and hospital utilization for pediatric MH concerns varied significantly by neighborhood and demographics. Divergent social factors map onto these locations and are related to MH utilization. Leveraging geography can be a powerful tool in the development of targeted, culturally tailored interventions to decrease acute pediatric MH utilization and advance child MH equity.

Parental Factors Affecting Pediatric Medication Management in Underserved Communities

BACKGROUND

Medication errors and adverse drug events are common in the pediatric population. Limited English proficiency and low health literacy have been associated with decreased medication adherence, increased medication errors, and worse health outcomes. This study explores parental factors affecting medication management in underserved communities.

METHODS

Using qualitative methods, we identified factors believed to affect medication management among parents. We conducted focus group discussions between December 2019 and September 2020. We recruited parents and health care professionals from local community partners and a tertiary care children's hospital. Sessions were recorded and transcribed. Three investigators created the coding scheme. Two investigators independently coded each focus group and organized results into themes using thematic analysis.

RESULTS

Eleven focus groups were held (n = 45): 4 English-speaking parent groups (n = 18), 3 Spanish-speaking parent groups (n = 11), and 4 health care professional groups (n = 16). We identified 4 main factors that could impact medication delivery: 1) limited health literacy among parents and feeling inadequate at medication administration (knowledge/skill gap), 2) poor communication between caregivers (regarding medication delivery, dosage, frequency, and purpose) and between providers (regarding what has been prescribed), 3) lack of pediatric medication education resources, and 4) personal attitudes and beliefs that influence one's medication-related decisions.

CONCLUSIONS

The compounding effect of these factors - knowledge, communication, resource, and personal belief - may put families living in underserved communities at greater risk for medication errors and suboptimal health outcomes. These findings can be used to guide future interventions and may help optimize medication delivery for pediatric patients.

Detection of Neisseria gonorrhoeae from Joint Aspirate by Metagenomic Sequencing in Disseminated Gonococcal Infection

Disseminated gonococcal infection (DGI) often manifests as gonococcal arthritis and may carry significant morbidity. However, diagnosis remains elusive due to limited sensitivity of available diagnostic tests. We used metagenomic next-generation sequencing to detect Neisseria gonorrhoeae from culture-negative joint aspirates of 2 patients with clinically diagnosed DGI.

Optimistic expectations have benefits for effort and emotion with little cost

The present investigation examined the potential benefits and costs of optimistic expectations about future events through the lens of error management theory (EMT). Decades of evidence have shown that optimism about the likelihood of future events is pervasive and difficult to correct. From an EMT perspective, this perpetuation of inaccurate beliefs is possible because optimism offers benefits greater than the costs. The present investigation examined this possibility for controllable important life events with a known time at which they would occur. College students taking their first exam (n = 1,061) and medical students being matched with residency placements (n = 182) reported their expectations and emotions weeks before the event and their responses after they knew the outcome of the event. Optimistic expectations predicted the quality of effort investment before an event occurred-students were more satisfied with their studying, medical students were more satisfied with their decision making, and optimism predicted better performance. Optimistic expectations also predicted less emotional distress before the event. There was no evidence that optimistic expectations related to longer-term greater distress when participants experienced an unexpected negative outcome; the valence of the outcome itself predicted distress. These results are consistent with the EMT-derived hypothesis that optimistic expectations have benefits for effort and emotion before an event occurs, with little cost after the outcome occurs. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

A Quality Improvement Initiative To Improve Postdischarge Antimicrobial Adherence

OBJECTIVES

Bedside delivery of discharge medications improves caregiver understanding and experience. Less is known about its impact on medication adherence. We aimed to improve antimicrobial adherence by increasing on-time first home doses for patients discharged from the pediatric hospital medicine service from 33% to 80% over 1 year via creation of a discharge medication delivery and counseling "Meds to Beds" (M2B) program.

METHODS

Using sequential plan-do-study-act cycles, an interprofessional workgroup implemented M2B on select pediatric hospital medicine units at our quaternary children's hospital from October 2017 through December 2018. Scripted telephone surveys were conducted with caregivers of patients prescribed antimicrobial agents at discharge. The primary outcome measure was on-time administration of the first home antimicrobial dose, defined as a dose given within the time of the inpatient dose equivalent plus 25%. Process measures primarily assessed caregiver report of barriers to adherence. Run charts, statistical process control charts, and inferential statistics were used for data analysis.

RESULTS

Caregiver survey response rate was 35% (207 of 585). Median on-time first home antimicrobial doses increased from 33% to 67% (P < .001). Forty percent of M2B prescriptions were adjusted before discharge because of financial or insurance barriers. M2B participants reported significantly less difficulty in obtaining medications compared with nonparticipants (1% vs 17%, P < .001).

CONCLUSIONS

The M2B program successfully increased parental report of timely administration of first home antimicrobial doses, a component of overall adherence. The program enabled providers to identify and resolve prescription problems before discharge. Importantly, caregivers reported reduced barriers to medication adherence.

Nestin in immature embryonic neurons affects axon growth cone morphology and Semaphorin3a sensitivity

Correct wiring in the neocortex requires that responses to an individual guidance cue vary among neurons in the same location, and within the same neuron over time. Nestin is an atypical intermediate filament expressed strongly in neural progenitors and is thus used widely as a progenitor marker. Here we show a subpopulation of embryonic cortical neurons that transiently express nestin in their axons. Nestin expression is thus not restricted to neural progenitors, but persists for 2-3 d at lower levels in newborn neurons. We found that nestin-expressing neurons have smaller growth cones, suggesting that nestin affects cytoskeletal dynamics. Nestin, unlike other intermediate filament subtypes, regulates cdk5 kinase by binding the cdk5 activator p35. Cdk5 activity is induced by the repulsive guidance cue Semaphorin3a (Sema3a), leading to axonal growth cone collapse in vitro. Therefore, we tested whether nestin-expressing neurons showed altered responses to Sema3a. We find that nestin-expressing newborn neurons are more sensitive to Sema3a in a roscovitine-sensitive manner, whereas nestin knockdown results in lowered sensitivity to Sema3a. We propose that nestin functions in immature neurons to modulate cdk5 downstream of the Sema3a response. Thus, the transient expression of nestin could allow temporal and/or spatial modulation of a neuron's response to Sema3a, particularly during early axon guidance.

Integrating Undergraduate Patient Partners into Diabetes self-management education: Evaluating a free clinic pilot program for the Underserved

BACKGROUND

Diabetes self-management education (DSME) improves glycemic control and health outcomes in patients with diabetes.

OBJECTIVE

A process evaluation of a two-year pilot intervention examined the feasibility and acceptability of undergraduate volunteers as Patient Partners to foster DSME participation among the underserved.Design setting, and participants. In the setting of a student-run free clinic, 22 patients enrolled in DSME were paired with 16 undergraduate volunteers. During the DSME courses, Patient Partners assisted patients during classes, called patients weekly, and accompanied patients to clinic appointments.Key process evaluation results. Average attendance at DSME classes was 79.4% and 94.7% for patients and Patient Partners, respectively. Sixty-three percent of phone calls were successful and Patient Partners attended 50% of appointments with their patients. Focus groups demonstrated resounding acceptability of the Patient Partner role.

CONCLUSIONS

Volunteer undergraduate Patient Partners are a beneficial adjunct to DSME delivery in the resource-constrained environment of a student-run free clinic.

An examination of child temperament as a predictor of parental post-operative analgesic administration

BACKGROUND/PURPOSE

The purpose of this study was to examine children's temperament as a predictor of post-operative analgesics administered by parents after controlling for post-operative pain severity, surgery severity, and parental misconceptions regarding pain medication for children.

METHODS

Participants included 286 Spanish- and English-speaking parents of children ages 1-18 (IQR: 3-8) undergoing outpatient elective surgery. Parents completed measures of baseline temperament, parental medication attitudes, and demographics preceding their child's surgery and recorded pain intensity and doses of analgesics administered (nonopioid and opioid) on postoperative days 1, 3, and 7.

RESULTS

Pearson product-moment correlations revealed that emotionality was significantly associated with acetaminophen, ibuprofen and hydrocodone and shyness was significantly associated with acetaminophen and hydrocodone. Hierarchical linear regression analysis revealed emotionality as a significant independent predictor of acetaminophen, ibuprofen and hydrocodone administered (F(4, 72)=2.82, F(4, 73)=1.53, F(4, 58)=8.75, respectively).

CONCLUSION

Dimensions of children's temperament, specifically emotionality, predict analgesic administration by parents following surgery even after controlling for confounding variables. These findings highlight the need for tailored interventions targeting management of children's pain in the home setting and suggest that both proximal (e.g., pain severity) and distal (e.g., child temperament) factors may be necessary intervention components.

CXCR4/IgG-expressing plasma cells are associated with human gastrointestinal tissue inflammation

BACKGROUND

We previously reported abnormalities in circulating B cells in patients with chronic granulomatous disease (CGD) and those with HIV infection. Gastrointestinal complications are common to both diseases and likely involve perturbation of immune cells, including plasma cells (PCs). IgA is the most abundant immunoglobulin in the human body, with roles in protection and maintenance of intestinal homeostasis. IgA is produced primarily by PCs residing in mucosal tissues that are also thought to circulate in the blood.

OBJECTIVE

We sought to characterize and compare PCs in patients with infectious (HIV) and noninfectious (CGD and Crohn disease) diseases that have been associated with intestinal inflammation.

METHODS

Phenotypic and transcriptional analyses were performed on cells isolated from the blood and colon.

RESULTS

IgA-secreting CCR10-expressing PCs predominated in the guts of healthy subjects, whereas in patients with HIV, CGD, and Crohn disease, there was a significant increase in the proportion of IgG-secreting PCs. Where intestinal inflammation was present, IgG-secreting PCs expressed reduced levels of CCR10 and increased levels of CXCR4. The intensity of CXCR4 expression correlated with the frequency of IgG-expressing PCs and the frequency of CXCR4(+)/IgG(+) PCs was associated with the severity of intestinal inflammatory disease yet distinct from PCs and plasmablasts circulating in the blood.

CONCLUSIONS

These findings suggest that regardless of the underlying disease, the presence of CXCR4(+)/IgG(+) PCs in the gut is a strong yet localized indicator of intestinal inflammation. Furthermore, our findings suggest that CXCR4(+)/IgG(+) PCs might play a role in immune cell homeostasis during inflammatory processes of the gut.

A diffusion barrier maintains distribution of membrane proteins in polarized neurons

The asymmetric distribution of proteins to distinct domains in the plasma membrane is crucial to the function of many polarized cells. In epithelia, distinct apical and basolateral surfaces are maintained by tight junctions that prevent diffusion of proteins and lipids between the two domains. Polarized neurons maintain axonal and somatodendritic plasma membrane domains without an obvious physical barrier. Indeed, the artificial lipid Dil encounters no diffusion barrier at the presumptive domain boundary, the axon hillock. By measuring the lateral mobility of membrane proteins using optical tweezers, we show here that some membrane proteins exhibit markedly reduced mobility in the initial segment of the axon. Disruption of F-actin and low levels of dimethyl sulphoxide (DMSO) abolish this diffusion barrier and lead to redistribution of membrane markers that had previously been polarized. Immobilization in the initial segment may reflect, at least in part, differential tethering to cytoskeletal components. Therefore, the ability to maintain a polarized distribution of membrane proteins depends on a specialized domain at the initial segment of the axon, which restricts lateral mobility and serves as a new type of diffusion barrier that acts in the absence of cell-cell contact.

Analysis of a cortical cytoskeletal structure: a role for ezrin-radixin-moesin (ERM proteins) in the marginal band of chicken erythrocytes

We are studying how the cytoskeleton determines cell shape, using a simple model system, the marginal band of chicken erythrocytes. We previously identified a minor component of the marginal band by a monoclonal antibody, called 13H9 (Birgbauer and Solomon (1989). J. Cell Biol. 109, 1609–1620; Goslin et al. (1989). J. Cell Biol. 109, 1621–1631). mAb 13H9 also binds to the leading edges of fibroblasts and to neuronal growth cones and recognizes the cytoskeletal protein ezrin. In recent years, two proteins with a high degree of homology to ezrin were identified: moesin and radixin, together comprising the ERM protein family. We now show that the contiguous epitope sufficient for mAb 13H9 binding is a sequence present in each of the ERM proteins, as well as the product of the gene associated with neurofibromatosis 2, merlin or schwannomin. We used biochemical and immunological techniques, as well as PCR to characterize the expression and localization of the ERM proteins in chicken erythrocytes. The results demonstrate that radixin is the major ERM protein associated with the cytoskeleton. Both ezrin and radixin localize to the position of the marginal band. Our results suggest that the ERM proteins play functionally conserved roles in quite diverse organelles.

Association of ezrin isoforms with the neuronal cytoskeleton

We are studying the changes in the organization of the cytoskeleton which accompany expression of differentiated neuronal morphology. Of particular interest is the elaboration of growth cones, the motile domains of the neuronal plasma membrane, and the cytoskeletal structures that underlie them. A candidate for a component of the growth cone cytoskeleton of cultured hippocampal neurons is the antigen recognized by the monoclonal antibody, 13H9 (Birgbauer and Solomon, J Cell Biol 109:1609-1620, 1989; Goslin et al., J Cell Biol 109:1621-1631, 1989). That antibody binds strongly to growth cones, but barely stains neurites. The characterization of the antigen, both biochemical and microscopic, suggests that it may interact with microfilaments and microtubules. We have established that 13H9 recognizes a subset of the isoforms of ezrin (unpublished results). Here, we describe the properties and localization of ezrin isoforms in differentiating neuronal cells, using two in vitro systems and developing spinal cord. In embryonal carcinoma cells, both the abundance of ezrin and the proportion of ezrin associated with the cytoskeletal fraction increase upon induction of neuronal differentiation with retinoic acid. In the neuronal cells within such cultures, the 13H9-positive forms of ezrin are enriched in the growth cone, while the bulk of ezrin identified by a polyclonal antibody shows no specific localization. In mouse DRG neurons, 13H9 staining is asymmetrically distributed along the edges of the complex growth cones of these cells. Staining of developing spinal cord in rat embryos also demonstrates that the 13H9-positive forms of ezrin do not colocalize with the majority of ezrin.(ABSTRACT TRUNCATED AT 250 WORDS)

A role for microtubule bundles in the morphogenesis of chicken erythrocytes

The acquisition of cellular asymmetry is one of the post-mitotic events in development. The cells of the avian erythropoietic lineage acquire a simple invariant asymmetry as they mature. Erythrocytes develop in suspension from spherical through discoid to lentil-shaped (lentiform) cells, with a single rigorously specified microtubule bundle, the marginal band. We show here that developing erythrocytes can express highly asymmetric morphologies, including elongated cell bodies and long processes in response to two stimuli: mechanical manipulation (repeated washing) and exposure to cytochalasin D. These experiments suggest that erythrocytes pass through a developmental stage during which microtubules are able to exert elongating forces on the cell. That stage is one in which these cells normally change shape, from spherical to discoid. The results suggest that microtubules may both guide and drive the formation of the marginal band and the characteristic morphology of these cells.

Temperature dependence of anion transport in the human red blood cell

Arrhenius plots of chloride and bromide transport yield two regions with different activation energies (Ea). Below 15 or 25 degrees C (for Cl- and Br-, respectively), Ea is about 32.5 kcal/mol; above these temperatures, about 22.5 kcal/mol (Brahm, J. (1977) J. Gen. Physiol. 70, 283-306). For the temperature dependence of SO4(2-) transport up to 37 degrees C, no such break could be observed. We were able to show that the temperature coefficient for the rate of SO4(2-) transport is higher than that for the rate of denaturation of the band 3 protein (as measured by NMR) or the destruction of the permeability barrier in the red cell membrane. It was possible, therefore, to extend the range of flux measurements up to 60 degrees C and to show that, even for the slowly permeating SO4(2-) in the Arrhenius plot, there appears a break, which is located somewhere between 30 and 37 degrees C and where Ea changes from 32.5 to 24.1 kcal/mol. At the break, the turnover number is approx. 6.9 ions/band 3 per s. Using 35Cl- -NMR (Falke, Pace and Chan (1984) J. Biol. Chem. 259, 6472-6480), we also determined the temperature dependence of Cl- -binding. We found no significant change over the entire range from 0 to 57 degrees C, regardless of whether the measurements were performed in the absence or presence of competing SO4(2-). We conclude that the enthalpy changes associated with Cl- - or SO4(2-)-binding are negligible as compared to the Ea values observed. It was possible, therefore, to calculate the thermodynamic parameters defined by transition-state theory for the transition of the anion-loaded transport protein to the activated state for Cl-, Br- and SO4(2-) below and above the temperatures at which the breaks in the Arrhenius plots are seen. We found in both regions a high positive activation entropy, resulting in a low free enthalpy of activation. Thus the internal energy required for carrying the complex between anion and transport protein over the rate-limiting energy barrier is largely compensated for by an increase of randomness in the protein and/or its aqueous environment.