Profilin and Mical combine to impair F-actin assembly and promote disassembly and remodeling.

Cellular events require the spatiotemporal interplay between actin assembly and actin disassembly. Yet, how different factors promote the integration of these two opposing processes is unclear. In particular, cellular monomeric (G)-actin is complexed with profilin, which inhibits spontaneous actin nucleation but fuels actin filament (F-actin) assembly by elongation-promoting factors (formins, Ena/VASP). In contrast, site-specific F-actin oxidation by Mical promotes F-actin disassembly and release of polymerization-impaired Mical-oxidized (Mox)-G-actin. Here we find that these two opposing processes connect with one another to orchestrate actin/cellular remodeling. Specifically, we find that profilin binds Mox-G-actin, yet these complexes do not fuel elongation factors'-mediated F-actin assembly, but instead inhibit polymerization and promote further Mox-F-actin disassembly. Using Drosophila as a model system, we show that similar profilin-Mical connections occur in vivo - where they underlie F-actin/cellular remodeling that accompanies Semaphorin-Plexin cellular/axon repulsion. Thus, profilin and Mical combine to impair F-actin assembly and promote F-actin disassembly, while concomitantly facilitating cellular remodeling and plasticity.

Propagation of F-actin disassembly via Myosin15-Mical interactions.

The F-actin cytoskeleton drives cellular form and function. However, how F-actin-based changes occur with spatiotemporal precision and specific directional orientation is poorly understood. Here, we identify that the unconventional class XV myosin [Myosin 15 (Myo15)] physically and functionally interacts with the F-actin disassembly enzyme Mical to spatiotemporally position cellular breakdown and reconstruction. Specifically, while unconventional myosins have been associated with transporting cargo along F-actin to spatially target cytoskeletal assembly, we now find they also target disassembly. Myo15 specifically positions this F-actin disassembly by associating with Mical and using its motor and MyTH4-FERM cargo-transporting functions to broaden Mical's distribution. Myo15's broadening of Mical's distribution also expands and directionally orients Mical-mediated F-actin disassembly and subsequent cellular remodeling, including in response to Semaphorin/Plexin cell surface activation signals. Thus, we identify a mechanism that spatiotemporally propagates F-actin disassembly while also proposing that other F-actin-trafficked-cargo is derailed by this disassembly to directionally orient rebuilding.

Effects of Bardoxolone Methyl on QT Interval in Healthy Volunteers.

BACKGROUND: Bardoxolone methyl has been shown to increase eGFR in several clinical trials, including a phase 3 trial in patients with type 2 diabetes and stage 4 CKD (BEACON), which was terminated early due to an increase in heart failure events in bardoxolone methyl-treated patients. A separate, "thorough QT" study was conducted in parallel with BEACON to evaluate the cardiovascular safety of bardoxolone methyl in healthy subjects. METHODS: Subjects in the "thorough QT" study were randomized to receive bardoxolone methyl 20 mg (therapeutic dose) or 80 mg (supratherapeutic dose), placebo, or moxifloxacin (400 mg; an active comparator). ECG results and supine blood pressure measurements were analyzed. The effects of bardoxolone methyl on QT interval changes from baseline were quantified compared to the effect of placebo by calculating mean, time-matched, placebo-corrected, baseline-adjusted QTcF values (ΔΔQTcF) after 6 days of daily administration of bardoxolone methyl. RESULTS: The study was halted early due to emerging safety information from the BEACON trial; however, 142/179 patients received all doses of the study drug and completed the study. For both bardoxolone methyl-treated groups (20 and 80 mg), the upper limits of the 2-sided 90% confidence interval for ΔΔQTcF were less than the significance limit (10 ms) at all time points. Changes in blood pressure were similar in all treatment groups, and no serious adverse events were reported. CONCLUSIONS: In healthy subjects, treatment with 20 or 80 mg bardoxolone methyl did not affect the QTcF interval.

Axon formation, extension, and navigation: only a neuroscience phenomenon?

Understanding how neurons form, extend, and navigate their finger-like axonal and dendritic processes is crucial for developing therapeutics for the diseased and damaged brain. Although less well appreciated, many other types of cells also send out similar finger-like projections. Indeed, unlike neuronal specific phenomena such as synapse formation or synaptic transmission, an important issue for thought is that this critical long-standing question of how a cellular process like an axon or dendrite forms and extends is not primarily a neuroscience problem but a cell biological problem. In that case, the use of simple cellular processes - such as the bristle cell process of Drosophila - can aid in the fight to answer these critical questions. Specifically, determining how a model cellular process is generated can provide a framework for manipulations of all types of membranous process-containing cells, including different types of neurons.

F-actin dismantling through a redox-driven synergy between Mical and cofilin.

Numerous cellular functions depend on actin filament (F-actin) disassembly. The best-characterized disassembly proteins, the ADF (actin-depolymerizing factor)/cofilins (encoded by the twinstar gene in Drosophila), sever filaments and recycle monomers to promote actin assembly. Cofilin is also a relatively weak actin disassembler, posing questions about mechanisms of cellular F-actin destabilization. Here we uncover a key link to targeted F-actin disassembly by finding that F-actin is efficiently dismantled through a post-translational-mediated synergism between cofilin and the actin-oxidizing enzyme Mical. We find that Mical-mediated oxidation of actin improves cofilin binding to filaments, where their combined effect dramatically accelerates F-actin disassembly compared with either effector alone. This synergism is also necessary and sufficient for F-actin disassembly in vivo, magnifying the effects of both Mical and cofilin on cellular remodelling, axon guidance and Semaphorin-Plexin repulsion. Mical and cofilin, therefore, form a redox-dependent synergistic pair that promotes F-actin instability by rapidly dismantling F-actin and generating post-translationally modified actin that has altered assembly properties.

Real-Time PCR Assay for Detection and Differentiation of Shiga Toxin-Producing Escherichia coli from Clinical Samples.

Timely accurate diagnosis of Shiga toxin-producing Escherichia coli (STEC) infections is important. We evaluated a laboratory-developed real-time PCR (LD-PCR) assay targeting stx1, stx2, and rfbEO157 with 2,386 qualifying stool samples submitted to the microbiology laboratory of a tertiary care pediatric center between July 2011 and December 2013. Broth cultures of PCR-positive samples were tested for Shiga toxins by enzyme immunoassay (EIA) (ImmunoCard STAT! enterohemorrhagic E. coli [EHEC]; Meridian Bioscience) and cultured in attempts to recover both O157 and non-O157 STEC. E. coli O157 and non-O157 STEC were detected in 35 and 18 cases, respectively. Hemolytic uremic syndrome (HUS) occurred in 12 patients (10 infected with STEC O157, one infected with STEC O125ac, and one with PCR evidence of STEC but no resulting isolate). Among the 59 PCR-positive STEC specimens from 53 patients, only 29 (54.7%) of the associated specimens were toxin positive by EIA. LD-PCR differentiated STEC O157 from non-O157 using rfbEO157, and LD-PCR results prompted successful recovery of E. coli O157 (n = 25) and non-O157 STEC (n = 8) isolates, although the primary cultures and toxin assays were frequently negative. A rapid "mega"-multiplex PCR (FilmArray gastrointestinal panel; BioFire Diagnostics) was used retrospectively, and results correlated with LD-PCR findings in 25 (89%) of the 28 sorbitol-MacConkey agar culture-negative STEC cases. These findings demonstrate that PCR is more sensitive than EIA and/or culture and distinguishes between O157 and non-O157 STEC in clinical samples and that E. coli O157:H7 remains the predominant cause of HUS in our institution. PCR is highly recommended for rapid diagnosis of pediatric STEC infections.

Implementation of filmarray respiratory viral panel in a core laboratory improves testing turnaround time and patient care.

The FilmArray respiratory virus panel detects 15 viral agents in respiratory specimens using polymerase chain reaction. We performed FilmArray respiratory viral testing in a core laboratory at a regional children's hospital that provides service 24 hours a day 7 days a week. The average and median turnaround time were 1.6 and 1.4 hours, respectively, in contrast to 7 and 6.5 hours documented 1 year previously at an on-site reference laboratory using a direct fluorescence assay (DFA) that detected 8 viral agents. During the study period, rhinovirus was detected in 20% and coronavirus in 6% of samples using FilmArray; these viruses would not have been detected with DFA. We followed 97 patients with influenza A or influenza B who received care at the emergency department (ED). Overall, 79 patients (81%) were given oseltamivir in a timely manner defined as receiving the drug in the ED, a prescription in the ED, or a prescription within 3 hours of ED discharge. Our results demonstrate that molecular technology can be successfully deployed in a nonspecialty, high-volume, multidisciplinary core laboratory.

Predictors of body size stigmatization in Hispanic preschool children.

OBJECTIVE: The purpose of the current study was to verify the occurrence of body size stigmatization in Hispanic preschoolers who are "at risk" for obesity and to examine potential predictors of body size stigmatization. METHODS AND PROCEDURES: At a local preschool, 70 lower-socioeconomic, Hispanic caregivers and their preschoolers participated. Preschoolers completed an attribution task including positive and negative adjectives to assess body size stigmatization. Child's perceived size and caregiver's body dissatisfaction were assessed using a line drawing ranging in size from very underweight figures to very overweight figures. Adult and child body indices were then assessed. RESULTS: Body size stigmatization in child participants was observed. Stepwise multiple regressions revealed that child BMI was the only significant predictor of the number of positive adjectives the child assigned to the overweight picture. As child BMI increased, the number of positive adjectives assigned to the overweight picture decreased. Two predictors, caregiver body dissatisfaction with self and caregiver BMI, significantly predicted the number of negative traits the child assigned to the overweight figure. Caregivers with higher BMIs and increased body dissatisfaction were most likely to have children who showed negative body size stigmatization. DISCUSSION: Increasing rates of obesity have not led to greater acceptance of the obese and even children who are at greater risk for obesity show body size stigmatization at early ages. Caregivers are influential in the development of body size stigmatization in children and must be considered in the development of programs aimed at reducing stigmatization and obesity.

Body mass index, disordered eating behavior, and acquisition of health information: examining ethnicity and weight-related issues in a college population.

OBJECTIVE AND PARTICIPANTS: To investigate ethnic differences related to weight, the authors assessed body mass index, dysfunctional eating, receipt of health information, and perceived obstacles to healthy lifestyles of 210 ethnically diverse college women. METHODS: The authors used the Eating Attitudes Test to assess dieting, food preoccupation, and bulimic behaviors. RESULTS: The authors found no ethnic differences in body mass index or disordered eating, but African Americans were more likely than were European Americans and Latina Americans to receive nutrition information from professionals and less likely than European Americans to perceive time as an obstacle. Overall, receipt of health information from a professional was related to fewer disordered eating behaviors; however, the specific eating behavior that was reduced varied by ethnicity. CONCLUSIONS: Health professionals should reconsider traditional assumptions of disordered eating behavior as a European American problem and consider cultural appropriateness in the development of effective health programs.

Mothers of preschoolers report using less pressure in child feeding situations following a newsletter intervention.

OBJECTIVE: To determine the impact of written intervention materials on child feeding practices of mothers and on physical activity behaviors of preschoolers. DESIGN: Mothers were divided into 3 groups: newsletter (n = 30), booklet (n = 31), and control (n = 31). Questionnaires were completed before and after a 12-week intervention. SETTING: Mail correspondence. PARTICIPANTS: White (90%), full-time mothers (76%) in their thirties (68%). INTERVENTIONS: Nutrition and activity information was provided as twelve 4-page weekly newsletters or one 52-page booklet. MAIN OUTCOME MEASURES: Child feeding factors, physical activity practices. ANALYSIS: Child feeding factors were analyzed using Kruskal-Wallis and Wilcoxon. Physical activity practices were analyzed using 2-way chi-square and sign tests. The significance level was set at .0125. RESULTS: There was a significant decrease in the "pressure to eat" score for participants in the newsletter group (2.5 +/- 1.0 to 2.1 +/- 1.0, P < .01). No other differences in feeding practices were observed. At baseline, 43% of the mothers said their child spent at least 1 hour per day in active play, and 63% said their child watched television less than 2 hours per day. A significant increase in outdoor play was reported in the newsletter (P < .01) and control (P < .01) groups. CONCLUSIONS AND IMPLICATIONS: This study is one of the first to indicate that child feeding practices may be modifiable.

Perceptions of health status and play activities in parents of overweight Hispanic toddlers and preschoolers.

Childhood overweight among lower socioeconomic, Hispanic children has increased. Interviews regarding health status and play patterns were conducted with 76 predominantly Hispanic mothers of overweight toddlers and preschoolers served by Women, Infants, and Children (WIC). Most participants believed their child was healthy and half were unconcerned about their child's weight. Most parents reported having a safe place to play and access to a playground, although gender differences were found. Access to an outside play area was related to amount of active play activities. Children watched an average of 1.7 hours per day of television. Health professionals must partner with parents to address childhood obesity.