Toward a better understanding of nonoccupational sound exposures and associated health impacts: Methods of the Apple Hearing Study.

Globally, noise exposure from occupational and nonoccupational sources is common, and, as a result, noise-induced hearing loss affects tens of millions of people. Occupational noise exposures have been studied and regulated for decades, but nonoccupational sound exposures are not well understood. The nationwide Apple Hearing Study, launched using the Apple research app in November 2019 (Apple Inc., Cupertino, CA), is characterizing the levels at which participants listen to headphone audio content, as well as their listening habits. This paper describes the methods of the study, which collects data from several types of hearing tests and uses the Apple Watch noise app to measure environmental sound levels and cardiovascular metrics. Participants, all of whom have consented to participate and share their data, have already contributed nearly 300 × 106 h of sound measurements and 200 000 hearing assessments. The preliminary results indicate that environmental sound levels have been higher, on average, than headphone audio, about 10% of the participants have a diagnosed hearing loss, and nearly 20% of the participants have hearing difficulty. The study's analyses will promote understanding of the overall exposures to sound and associated impacts on hearing and cardiovascular health. This study also demonstrates the feasibility of collecting clinically relevant exposure and health data outside of traditional research settings.

FMNL formins boost lamellipodial force generation.

Migration frequently involves Rac-mediated protrusion of lamellipodia, formed by Arp2/3 complex-dependent branching thought to be crucial for force generation and stability of these networks. The formins FMNL2 and FMNL3 are Cdc42 effectors targeting to the lamellipodium tip and shown here to nucleate and elongate actin filaments with complementary activities in vitro. In migrating B16-F1 melanoma cells, both formins contribute to the velocity of lamellipodium protrusion. Loss of FMNL2/3 function in melanoma cells and fibroblasts reduces lamellipodial width, actin filament density and -bundling, without changing patterns of Arp2/3 complex incorporation. Strikingly, in melanoma cells, FMNL2/3 gene inactivation almost completely abolishes protrusion forces exerted by lamellipodia and modifies their ultrastructural organization. Consistently, CRISPR/Cas-mediated depletion of FMNL2/3 in fibroblasts reduces both migration and capability of cells to move against viscous media. Together, we conclude that force generation in lamellipodia strongly depends on FMNL formin activity, operating in addition to Arp2/3 complex-dependent filament branching.

Stabilization of glycemic control and improved quality of life using a shared medical appointment model in adolescents with type 1 diabetes in suboptimal control.

BACKGROUND: Declining glycemic control in type 1 diabetes (T1D) during adolescence persists despite treatment advances. Non-adherence, peer relations, diabetes burnout, risk taking, transition to autonomy, family conflict, and poor quality of life (QOL) are recognized barriers. Shared medical appointments (SMAs) in adolescent T1D may offer benefits, but data are limited. Our objective was to determine whether SMAs, with multi-component interventions utilizing multidisciplinary teams, improve glycemic control and psychosocial outcomes in poorly controlled adolescent T1D. METHODS: SMAs focused on self-management, communication skills, goal setting, glucose pattern recognition, and peer/diabetes team support. SMAs included: individual history and physical, labs, surveys, multidisciplinary educational ice breakers, group session, and individual wrap up. Outcomes were QOL, adherence, and retrospective and prospective glycemic control. Three to six subjects and families came to 3 SMAs and 1 individual appointment every 3 months over 9 months. SUBJECTS: A total of 37 English speaking subjects, ages 12-16 yrs, with T1D ≥ 1 year, and hemoglobin A1c (HbA1c) 7.5-11% enrolled. Thirty-two subjects attended 75% of visits, meeting inclusion criteria. RESULTS: HbA1c worsened in the 9 months before study (ΔHbA1c= 0.7 ± 1.2; p < 0.01), but remained stable during study (ΔHbA1c = 0.01 ± 1.2; p > 0.05). There were significant improvements in overall QOL (p = 0.005), school function (p = 0.006), psychosocial function (p = 0.008), barriers (p = 0.02), adherence (p = 0.01), and communication (p = 0.02). Improvements in school function and communication reached clinical significance. CONCLUSION: SMAs are feasible replacements to individual appointments in adolescent T1D, stabilizing glycemic control and improving QOL. Randomized controlled trials with optimizations are needed to further explore and refine this intervention.

The structure of FMNL2-Cdc42 yields insights into the mechanism of lamellipodia and filopodia formation.

Formins are actin polymerization factors that elongate unbranched actin filaments at the barbed end. Rho family GTPases activate Diaphanous-related formins through the relief of an autoregulatory interaction. The crystal structures of the N-terminal domains of human FMNL1 and FMNL2 in complex with active Cdc42 show that Cdc42 mediates contacts with all five armadillo repeats of the formin with specific interactions formed by the Rho-GTPase insert helix. Mutation of three residues within Rac1 results in a gain-of-function mutation for FMNL2 binding and reconstitution of the Cdc42 phenotype in vivo. Dimerization of FMNL1 through a parallel coiled coil segment leads to formation of an umbrella-shaped structure that­together with Cdc42­spans more than 15 nm in diameter. The two interacting FMNL-Cdc42 heterodimers expose six membrane interaction motifs on a convex protein surface, the assembly of which may facilitate actin filament elongation at the leading edge of lamellipodia and filopodia.

A web-based study of the relationship of duration of insulin pump infusion set use and fasting blood glucose level in adults with type 1 diabetes.

BACKGROUND: To evaluate the impact of infusion set use duration on glycemic control, we conducted an Internet-based study using the T1D Exchange's online patient community, Glu ( myGlu.org ). SUBJECTS AND METHODS: For 14 days, 243 electronically consented adults with type 1 diabetes (T1D) entered online that day's fasting blood glucose (FBG) level, the prior day's total daily insulin (TDI) dose, and whether the infusion set was changed. RESULTS: Mean duration of infusion set use was 3.0 days. Mean FBG level was higher with each successive day of infusion set use, increasing from 126 mg/dL on Day 1 to 133 mg/dL on Day 3 to 147 mg/dL on Day 5 (P<0.001). TDI dose did not vary with increased duration of infusion set use. CONCLUSIONS: Internet-based data collection was used to rapidly conduct the study at low cost. The results indicate that FBG levels increase with each additional day of insulin pump infusion set use.

Insulin pump use in young children in the T1D Exchange clinic registry is associated with lower hemoglobin A1c levels than injection therapy.

Insulin delivery via injection and continuous subcutaneous insulin infusion (CSII) via insulin pump were compared in a cross-sectional study (n = 669) and retrospective longitudinal study (n = 1904) of young children (<6 yr) with type 1 diabetes (T1D) participating in the T1D Exchange clinic registry. Use of CSII correlated with longer T1D duration (p < 0.001), higher parental education (p < 0.001), and annual household income (p < 0.006) but not with race/ethnicity. Wide variation in pump use was observed among T1D Exchange centers even after adjusting for these factors, suggesting that prescriber preference is a substantial determinant of CSII use. Hemoglobin A1c (HbA1c) was lower in pump vs. injection users (7.9 vs. 8.5%, adjusted p < 0.001) in the cross-sectional study. In the longitudinal study, HbA1c decreased after initiation of CSII by 0.2%, on average (p < 0.001). Frequency of a severe hypoglycemia (SH) event did not differ in pump vs. injection users (p = 0.2). Frequency of ≥1 parent-reported diabetic ketoacidosis (DKA) event in the prior year was greater in pump users than injection users (10 vs. 8%, p = 0.04). No differences between pump and injection users were observed for clinic-reported DKA events. Children below 6 yr have many unique metabolic characteristics, feeding behaviors, and care needs compared with older children and adolescents. These data support the use of insulin pumps in this youngest age group, and suggest that metabolic control may be improved without increasing the frequency of SH, but care should be taken as to the possibly increased risk of DKA.

FMNL2 drives actin-based protrusion and migration downstream of Cdc42.

Cell migration entails protrusion of lamellipodia, densely packed networks of actin filaments at the cell front. Filaments are generated by nucleation, likely mediated by Arp2/3 complex and its activator Scar/WAVE. It is unclear whether formins contribute to lamellipodial actin filament nucleation or serve as elongators of filaments nucleated by Arp2/3 complex. Here we show that the Diaphanous-related formin FMNL2, also known as FRL3 or FHOD2, accumulates at lamellipodia and filopodia tips. FMNL2 is cotranslationally modified by myristoylation and regulated by interaction with the Rho-guanosine triphosphatase Cdc42. Abolition of myristoylation or Cdc42 binding interferes with proper FMNL2 activation, constituting an essential prerequisite for subcellular targeting. In vitro, C-terminal FMNL2 drives elongation rather than nucleation of actin filaments in the presence of profilin. In addition, filament ends generated by Arp2/3-mediated branching are captured and efficiently elongated by the formin. Consistent with these biochemical properties, RNAi-mediated silencing of FMNL2 expression decreases the rate of lamellipodia protrusion and, accordingly, the efficiency of cell migration. Our data establish that the FMNL subfamily member FMNL2 is a novel elongation factor of actin filaments that constitutes the first Cdc42 effector promoting cell migration and actin polymerization at the tips of lamellipodia.

Microtubules as platforms for assaying actin polymerization in vivo.

The actin cytoskeleton is continuously remodeled through cycles of actin filament assembly and disassembly. Filaments are born through nucleation and shaped into supramolecular structures with various essential functions. These range from contractile and protrusive assemblies in muscle and non-muscle cells to actin filament comets propelling vesicles or pathogens through the cytosol. Although nucleation has been extensively studied using purified proteins in vitro, dissection of the process in cells is complicated by the abundance and molecular complexity of actin filament arrays. We here describe the ectopic nucleation of actin filaments on the surface of microtubules, free of endogenous actin and interfering membrane or lipid. All major mechanisms of actin filament nucleation were recapitulated, including filament assembly induced by Arp2/3 complex, formin and Spir. This novel approach allows systematic dissection of actin nucleation in the cytosol of live cells, its genetic re-engineering as well as screening for new modifiers of the process.