Exercise microdosing for skeletal muscle health applications to spaceflight.

Findings from a recent 70-day bedrest investigation suggested intermittent exercise testing in the control group may have served as a partial countermeasure for skeletal muscle size, function, and fiber-type shifts. The purpose of the current study was to investigate the metabolic and skeletal muscle molecular responses to the testing protocols. Eight males (29 ± 2 yr) completed muscle power (6 × 4 s; peak muscle power: 1,369 ± 86 W) and V̇o2max (13 ± 1 min; 3.2 ± 0.2 L/min) tests on specially designed supine cycle ergometers during two separate trials. Blood catecholamines and lactate were measured pre-, immediately post-, and 4-h postexercise. Muscle homogenate and muscle fiber-type-specific [myosin heavy chain (MHC) I and MHC IIa] mRNA levels of exercise markers (myostatin, IκBα, myogenin, MuRF-1, ABRA, RRAD, Fn14, PDK4) and MHC I, IIa, and IIx were measured from vastus lateralis muscle biopsies obtained pre- and 4-h postexercise. The muscle power test altered (P ≤ 0.05) norepinephrine (+124%), epinephrine (+145%), lactate (+300%), and muscle homogenate mRNA (IκBα, myogenin, MuRF-1, RRAD, Fn14). The V̇o2max test altered (P ≤ 0.05) norepinephrine (+1,394%), epinephrine (+1,412%), lactate (+736%), and muscle homogenate mRNA (myostatin, IκBα, myogenin, MuRF-1, ABRA, RRAD, Fn14, PDK4). In general, both tests influenced MHC IIa muscle fibers more than MHC I with respect to the number of genes that responded and the magnitude of response. Both tests also influenced MHC mRNA expression in a muscle fiber-type-specific manner. These findings provide unique insights into the adaptive response of skeletal muscle to small doses of exercise and could help shape exercise dosing for astronauts and Earth-based individuals.NEW & NOTEWORTHY Declines in skeletal muscle health are a concern for astronauts on long-duration spaceflights. The current findings add to the growing body of exercise countermeasures data, suggesting that small doses of specific exercise can be beneficial for certain aspects of skeletal muscle health. This information can be used in conjunction with other components of existing exercise programs for astronauts and might translate to other areas focused on skeletal muscle health (e.g., sports medicine, rehabilitation, aging).

The structure of the human LACTB filament reveals the mechanisms of assembly and membrane binding.

Mitochondria are complex organelles that play a central role in metabolism. Dynamic membrane-associated processes regulate mitochondrial morphology and bioenergetics in response to cellular demand. In tumor cells, metabolic reprogramming requires active mitochondrial metabolism for providing key metabolites and building blocks for tumor growth and rapid proliferation. To counter this, the mitochondrial serine beta-lactamase-like protein (LACTB) alters mitochondrial lipid metabolism and potently inhibits the proliferation of a variety of tumor cells. Mammalian LACTB is localized in the mitochondrial intermembrane space (IMS), where it assembles into filaments to regulate the efficiency of essential metabolic processes. However, the structural basis of LACTB polymerization and regulation remains incompletely understood. Here, we describe how human LACTB self-assembles into micron-scale filaments that increase their catalytic activity. The electron cryo-microscopy (cryoEM) structure defines the mechanism of assembly and reveals how highly ordered filament bundles stabilize the active state of the enzyme. We identify and characterize residues that are located at the filament-forming interface and further show that mutations that disrupt filamentation reduce enzyme activity. Furthermore, our results provide evidence that LACTB filaments can bind lipid membranes. These data reveal the detailed molecular organization and polymerization-based regulation of human LACTB and provide new insights into the mechanism of mitochondrial membrane organization that modulates lipid metabolism.

Differences in Force Levels, Word Recognition in Quiet, Sentence Reception Threshold in Noise, and Subjective Outcomes for a Bone-Anchored Hearing Device Programmed Using Manufacturer First-Fit, Aided Sound-Field Thresholds and Programmed to DSL-BCD Using a Skull Simulator.

BACKGROUND: Best practice guidelines for verifying fittings of bone-anchored hearing devices (BAHD) recommend using aided sound-field thresholds (ASFT), but express caution regarding the variables impacting obtaining valid and reliable ASFTs.1 Recently, a skull simulator was introduced to facilitate programming BAHD devices in force level (FL) to desired sensation level-bone conduction devices (skull simulator/DSL-BCD)2 3 targets in a hearing aid analyzer. Currently, no evidence is available reporting if differences in measured FL using the manufacturer first-fit (FF) and word recognition in quiet, sentence reception threshold in noise, and subjective outcomes are present for a BAHD programmed using ASFT versus programmed using skull simulator/DSL-BCD targets. PURPOSE: The aim of this study was to examine if significant differences were present in FL using the FF and word recognition in quiet at 50 and 65 decibel of sound pressure level (dB SPL), sentence reception threshold in noise and subjective outcomes using the abbreviated profile of hearing aid benefit (APHAB), and speech, spatial, and qualities of hearing (SSQ) between a BAHD fit using ASFT or skull simulator/DSL-BCD targets. RESEARCH DESIGN: A double-blind randomized crossover design with 15 adults having unilateral sensorineural hearing loss. All participants were successful users of the Cochlear America Baha 5. DATA COLLECTION AND ANALYSIS: Baha Power 5 devices were fit using FF, ASFT, and skull simulator/DSL-BCD targets. Order of the three fitting strategies was randomly assigned and counter-balanced. RESULTS: No significant differences were found for a BAHD device programmed using ASFT versus skull simulator/DSL-BCD targets for consonant-nucleus-consonant words in quiet at 50 or 65 dB SPL, sentence reception threshold in noise, the APHAB or SSQ. There were, however, significant differences, at primarily 500 to 2,000 Hz in measured FLs between the FF, ASFT, and skull simulator/DSL-BCD targets at 50 and 65 dB SPL. CONCLUSIONS: There were no significant differences in subject performance with two speech measures and subjective responses to two questionnaires for BAHD fittings using ASFT versus using skull simulator/DSL-BCD targets. Differences in FL between the three fitting strategies were present primarily at 500 to 2,000 Hz. Limitations of the study are highlighted along with situations where the skull simulator can play a significantly beneficial role when fitting BAHD devices.

Accuracy of an Automated Hearing Aid Fitting Using Real Ear Measures Embedded in a Manufacturer Fitting Software.

BACKGROUND: Hearing aid fitting guidelines recommend real ear measures (REM) to verify hearing aid performance. Unfortunately, approximately 70 to 80% of clinicians do not use REM, but instead download manufacturer first-fit. Studies report differences in performance between first-fit and programmed-fit with greatest differences in the higher frequencies. Recently, hearing aid and real ear analyzer (REA) manufacturers allow REA communication with hearing aid software feature to automatically program hearing aids to target. Little research is available reporting the accuracy of this feature. PURPOSE: The aim of the study is to examine whether differences exist at 50, 65, and 80 dB SPL between two ReSound first-fit formulae (Audiogram+ and NAL-NL2) using ReSound AutoREM and Aurical NAL-NL2 RESEARCH DESIGN: The study design is of repeated measure type. STUDY SAMPLE: The study sample includes 48 ears. DATA COLLECTION AND ANALYSIS: For the two fitting formulae, AutoREM real ear insertion gain (REIG) was measured at 50, 65, and 80 dB SPL and compared with measures from Aurical NAL-NL2. RESULTS: Mean AutoREM REIG for ReSound NAL-NL2 was 3 to 8 dB below Aurical NAL-NL2 for 50 dB SPL, within 1 to 3 dB for 65 dB SPL and 1 to 5 dB above for 80 dB SPL. Mean AutoREM REIG for Audiogram + was 1 to 12 dB below Aurical NAL-NL2 for 50 dB SPL, within 2 to 5 dB for 65 dB SPL and 1 to 7 dB above NAL-NL2 for 80 dB SPL. CONCLUSION: Relative to the Aurical NAL-NL2, AutoREM REIG50 for Audiogram + and ReSound NAL-NL2 was lower. Relative to the Aurical NAL-NL2, AutoREM REIG65 for Audiogram + was higher at 1,000 Hz and lower at 4,000 to 6,000 Hz and for ReSound NAL-NL2 it was lower at 500 Hz and 4,000 Hz and higher at 3,000 Hz. Relative to the Aurical NAL-NL2, AutoREM REIG80 for Audiogram + was higher at 500 to 3,000 Hz and 6,000 Hz and ReSound NAL-NL2 was higher at 500 to 6,000 Hz. Because of wide intersubject variability clinicians should continue to use REM as a "check and balance" when using AutoREM.

Facebook groups provide effective social support to patients after bariatric surgery.

BACKGROUND: Social support after bariatric surgery is considered essential. Unfortunately, patient participation in such groups tends to be limited threatening their effectiveness. Facebook groups may provide a social support option that attracts more participation. The aim of this study was to describe our experience with the administration of a Facebook social support group and evaluate its perceived value by our bariatric patients. METHODS: After IRB approval, all Facebook group posts since its establishment in 2015 were reviewed and a thematic analysis was undertaken. Group members also completed a survey related to their Facebook group experience and its perceived value. Responses were collected using 5-point Likert scales. In addition, 30 members were phone interviewed using open-ended questions and their responses were analyzed. RESULTS: Over 4 years, the group accumulated 12,507 posts, 104,053 comments, and 197,594 reactions. On average, members check the group page more than once per day. Ten common themes were identified in the submitted posts: questions, motivation related, education related, diet related, physical activity related, current status updates, sharing failures, social, random/humorous and other. Members reported that the group helped them do well with their procedure (3.3/5) particularly due to the motivation of others' successful stories (3.5/5) and made them feel understood (3.9/5) even though it offered limited help controlling their eating habits (2.7/5). The phone interviews suggested that the Facebook group offered constant support, was simple to use, and provided the sole social support for many patients. They most appreciated the motivational posts that kept them on track and the assistance/comments of clinical staff. In contrast, they disliked repeated questions/spam and negative stories shared by some members. CONCLUSIONS: Facebook groups can provide effective social support to patients after bariatric surgery. Peers educate, answer questions, and motivate patients by sharing their positive experiences. Whether this online connectedness also positively impacts patient outcomes requires further study.