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Electrothermal actuators have many advantages compared to other actuators used in Micro-Electro-Mechanical Systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10-90% rise time of 85 μs in air and 234 μs in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10-90% rise time from 85 μs to 3 μs in air and from 234 μs to 5 μs in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate.

Background: Asian and multiracial individuals represent the 2 fastest growing racial and ethnic groups in the United States, yet most prior studies report Asian American and Native Hawaiian or Other Pacific Islander as a single racial group, with limited data on cardiovascular disease (CVD) prevalence among subgroups. We sought to evaluate temporal trends in CVD burden among disaggregated Asian subgroups., Methods and Results: Patients with CVD based on International Classification of Diseases, Ninth Revision and Tenth Revision ( ICD-9 and ICD-10 ) coding who received care from a mixed-payer health care organization in California between 2008 and 2018 were classified into self-identified racial and ethnic subgroups (non-Hispanic White [NHW], Asian Indian, Chinese, Filipino, Japanese, Korean, Native Hawaiian or Other Pacific Islander, and multiracial groups). Adjusted trends in CVD prevalence over time by subgroup were compared using logistic regression. Among 3 494 071 patient-years, prevalence of CVD increased faster among all subgroups except Japanese and Native Hawaiian or Other Pacific Islander patients ( P <0.01 for each, reference: NHW). Filipino patients had the highest overall CVD prevalence, which increased from 34.3% to 45.1% over 11 years (increase from 17.3%-21.9%, P <0.0001, reference: NHW). Asian Indian patients had the fastest increase in CVD prevalence over time (16.9%-23.7%, P <0.0001, reference: NHW). Among subcategories of disease, hypertension increased faster among Asian Indian, Chinese, Filipino, Korean, and multiracial groups ( P <0.01 for all, reference: NHW), and coronary artery disease increased faster among Asian Indian, Chinese, Filipino, and Japanese groups ( P <0.05 for each, reference: NHW)., Conclusions: The increasing prevalence of CVD among disaggregated Asian, Native Hawaiian or Other Pacific Islander, and multiracial subgroups over time highlights the importance of tailored approaches to addressing CVD in these diverse subpopulations.

Coronary artery calcium (CAC) is a powerful tool to refine atherosclerotic cardiovascular disease (ASCVD) risk assessment. Despite its growing interest, contemporary public attitudes around CAC are not well-described in literature and have important implications for shared decision-making around cardiovascular prevention. We used an artificial intelligence (AI) pipeline consisting of a semi-supervised natural language processing model and unsupervised machine learning techniques to analyze 5,606 CAC-related discussions on Reddit. A total of 91 discussion topics were identified and were classified into 14 overarching thematic groups. These included the strong impact of CAC on therapeutic decision-making, ongoing non-evidence-based use of CAC testing, and the patient perceived downsides of CAC testing (e.g., radiation risk). Sentiment analysis also revealed that most discussions had a neutral (49.5%) or negative (48.4%) sentiment. The results of this study demonstrate the potential of an AI-based approach to analyze large, publicly available social media data to generate insights into public perceptions about CAC, which may help guide strategies to improve shared decision-making around ASCVD management and public health interventions., (© 2024. The Author(s).)

Background: Coronary artery calcium (CAC) is a strong predictor of cardiovascular events across all racial and ethnic groups. CAC can be quantified on nonelectrocardiography (ECG)-gated computed tomography (CT) performed for other reasons, allowing for opportunistic screening for subclinical atherosclerosis., Objectives: The authors investigated whether incidental CAC quantified on routine non-ECG-gated CTs using a deep-learning (DL) algorithm provided cardiovascular risk stratification beyond traditional risk prediction methods., Methods: Incidental CAC was quantified using a DL algorithm (DL-CAC) on non-ECG-gated chest CTs performed for routine care in all settings at a large academic medical center from 2014 to 2019. We measured the association between DL-CAC (0, 1-99, or ≥100) with all-cause death (primary outcome), and the secondary composite outcomes of death/myocardial infarction (MI)/stroke and death/MI/stroke/revascularization using Cox regression. We adjusted for age, sex, race, ethnicity, comorbidities, systolic blood pressure, lipid levels, smoking status, and antihypertensive use. Ten-year atherosclerotic cardiovascular disease risk was calculated using the pooled cohort equations., Results: Of 5,678 adults without ASCVD (51% women, 18% Asian, 13% Hispanic/Latinx), 52% had DL-CAC >0. Those with DL-CAC ≥100 had an average 10-year ASCVD risk of 24%; yet, only 26% were on statins. After adjustment, patients with DL-CAC ≥100 had increased risk of death (HR: 1.51; 95% CI: 1.28-1.79), death/MI/stroke (HR: 1.57; 95% CI: 1.33-1.84), and death/MI/stroke/revascularization (HR: 1.69; 95% CI: 1.45-1.98) compared with DL-CAC = 0., Conclusions: Incidental CAC ≥100 was associated with an increased risk of all-cause death and adverse cardiovascular outcomes, beyond traditional risk factors. DL-CAC from routine non-ECG-gated CTs identifies patients at increased cardiovascular risk and holds promise as a tool for opportunistic screening to facilitate earlier intervention., Competing Interests: Funding Support and Author Disclosures This work was supported by the Stanford University Human-Centered Artificial Intelligence Seed Grant. Mr Khandwala and Mr Eng are employees and shareholders of Bunkerhill Health. Dr Chaudhari has received research support from the Stanford University Precision Health and Integrated Diagnostics Seed Grant and the Stanford University Human-Centered Artificial Intelligence–Artificial Intelligence in Medicine and Imaging Seed Grant; has provided consulting services to Subtle Medical, Chondrometrics GmbH, Image Analysis Group, Edge Analytics, ICM, and Culvert Engineering; is a shareholder of Subtle Medical, LVIS Corporation, and Brain Key; and receives research support from GE Healthcare and Philips, all outside of the submitted work. Dr Sandhu has received research support from the National Heart, Lung, and Blood Institute (1K23HL151672-01). Dr Rodriguez was funded by grants from the National Institutes of Health National Heart, Lung, and Blood Institute (1K01HL144607), the American Heart Association/Harold Amos Faculty Development program, and the Doris Duke Foundation (Grant #2022051); and has consulting relationships with Healthpals, Novartis, Novo Nordisk, Esperion, and AstraZeneca outside of the submitted work. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Hair cells of the auditory and vestibular systems transform mechanical input into electrical potentials through the mechanoelectrical transduction process (MET). Deflection of the mechanosensory hair bundle increases tension in the gating springs that open MET channels. Regulation of MET channel sensitivity contributes to the auditory system's precision, wide dynamic range and, potentially, protection from overexcitation. Modulating the stiffness of the gating spring modulates the sensitivity of the MET process. Here, we investigated the role of cyclic adenosine monophosphate (cAMP) in rat outer hair cell MET and found that cAMP up-regulation lowers the sensitivity of the channel in a manner consistent with decreasing gating spring stiffness. Direct measurements of the mechanical properties of the hair bundle confirmed a decrease in gating spring stiffness with cAMP up-regulation. In parallel, we found that prolonged depolarization mirrored the effects of cAMP. Finally, a limited number of experiments implicate that cAMP activates the exchange protein directly activated by cAMP to mediate the changes in MET sensitivity. These results reveal that cAMP signaling modulates gating spring stiffness to affect auditory sensitivity.

In the inner ear, the auditory and vestibular systems detect and translate sensory information regarding sound and balance. The sensory cells that transform mechanical input into an electrical signal in these systems are called hair cells. A specialized organelle on the apical surface of hair cells called the hair bundle detects mechanical signals. Displacement of the hair bundle causes mechanotransduction channels to open. The morphology and organization of the hair bundle, as well as the properties and characteristics of the mechanotransduction process, differ between the different hair cell types in the auditory and vestibular systems. These differences likely contribute to maximizing the transduction of specific signals in each system. This review will discuss the molecules essential for mechanotransduction and the properties of the mechanotransduction process, focusing our attention on recent data and differences between the auditory and vestibular systems., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Aims: Coronary artery calcium (CAC) burden displays a stepwise association with atherosclerotic cardiovascular disease (ASCVD) risk. Among primary prevention patients, we sought to determine the CAC scores equivalent to ASCVD mortality rates observed in the FOURIER trial, a modern secondary prevention cohort., Methods and Results: For the main analysis, we included participants from the CAC Consortium ≥50 years old with a 10-year ASCVD risk ≥7.5% (n = 20,207). Poisson regression was used to define the relationship between CAC and annual ASCVD mortality. Equations generated from the regression models were then used to derive CAC scores associated with equivalent annual ASCVD mortality as observed in FOURIER placebo participants from the overall trial and in key trial subgroups. The CAC Consortium participants had a similar age (65.5 versus 62.5 years) and sex (22% versus 24% female) distribution as FOURIER. The annualized ASCVD mortality rate in FOURIER participants (0.766 per 100 person-years) corresponded to a CAC score of 781 (418-1467). A CAC score of 255 (162-394) corresponded to an ASCVD mortality rate equivalent to the lowest risk FOURIER subgroup (presence of myocardial infarction >2 years prior to trial enrollment). No CAC score produced a risk equivalent to high-risk FOURIER subgroups, particularly those with symptomatic peripheral arterial disease and/or multivessel coronary heart disease., Conclusions: Primary prevention individuals with increased CAC burden may have annualized ASCVD mortality rates equivalent to persons with stable secondary prevention-level risk. These findings argue for a risk continuum between higher risk primary prevention and stable secondary prevention patients, as their ASCVD risks may overlap., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Hair cell mechanosensitivity resides in the sensory hair bundle, an apical protrusion of actin-filled stereocilia arranged in a staircase pattern. Hair bundle deflection activates mechano-electric transduction (MET) ion channels located near the tops of the shorter rows of stereocilia. The elicited macroscopic current is shaped by the hair bundle motion so that the mode of stimulation greatly influences the cell's output. We present data quantifying the displacement of the whole outer hair cell bundle using high-speed imaging when stimulated with a fluid jet. We find a spatially non-uniform stimulation that results in splaying, where the hair bundle expands apart. Based on modeling, the splaying is predominantly due to fluid dynamics with a small contribution from hair bundle architecture. Additionally, in response to stimulation, the hair bundle exhibited a rapid motion followed by a slower motion in the same direction (creep) that is described by a double exponential process. The creep is consistent with originating from a linear passive system that can be modeled using two viscoelastic processes. These viscoelastic mechanisms are integral to describing the mechanics of the mammalian hair bundle., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Peng, Scharr, Caprara, Nettles, Steele and Ricci.)

Background: There are limited data on the unique cardiovascular disease (CVD), non-CVD, and mortality risks of primary prevention individuals with very high coronary artery calcium (CAC; ≥1000), especially compared with rates observed in secondary prevention populations., Methods: Our study population consisted of 6814 ethnically diverse individuals 45 to 84 years of age who were free of known CVD from MESA (Multi-Ethnic Study of Atherosclerosis), a prospective, observational, community-based cohort. Mean follow-up time was 13.6±4.4 years. Hazard ratios of CAC ≥1000 were compared with both CAC 0 and CAC 400 to 999 for CVD, non-CVD, and mortality outcomes with the use of Cox proportional hazards regression adjusted for age, sex, and traditional risk factors. Using a sex-adjusted logarithmic model, we calculated event rates in MESA as a function of CAC and compared them with those observed in the placebo group of stable secondary prevention patients in the FOURIER clinical trial (Further Cardiovascular Outcomes Research With PCSK9 Inhibition in Subjects With Elevated Risk)., Results: Compared with CAC 400 to 999, those with CAC ≥1000 (n=257) had a greater mean number of coronary vessels with CAC (3.4±0.5), greater total area of CAC (586.5±275.2 mm 2 ), similar CAC density, and more extensive extracoronary calcification. After full adjustment, CAC ≥1000 demonstrated a 4.71- (3.63-6.11), 7.57- (5.50-10.42), 4.86-(3.32-7.11), and 1.94-fold (1.57-2.41) increased risk for all CVD events, all coronary heart disease events, hard coronary heart disease events, and all-cause mortality, respectively, compared with CAC 0 and a 1.65- (1.25-2.16), 1.66- (1.22-2.25), 1.51- (1.03-2.23), and 1.34-fold (1.05-1.71) increased risk compared with CAC 400 to 999. With increasing CAC, hazard ratios increased for all event types, with no apparent upper CAC threshold. CAC ≥1000 was associated with a 1.95- (1.57-2.41) and 1.43-fold (1.12-1.83) increased risk for a first non-CVD event compared with CAC 0 and CAC 400 to 999, respectively. CAC 1000 corresponded to an annualized 3-point major adverse cardiovascular event rate of 3.4 per 100 person-years, similar to that of the total FOURIER population (3.3) and higher than those of the lower-risk FOURIER subgroups., Conclusions: Individuals with very high CAC (≥1000) are a unique population at substantially higher risk for CVD events, non-CVD outcomes, and mortality than those with lower CAC, with 3-point major adverse cardiovascular event rates similar to those of a stable treated secondary prevention population. Future guidelines should consider a less distinct stratification algorithm between primary and secondary prevention patients in guiding aggressive preventive pharmacotherapy.

Hair cells detect sound and motion through a mechano-electric transduction (MET) process mediated by tip links connecting shorter stereocilia to adjacent taller stereocilia. Adaptation is a key feature of MET that regulates a cell's dynamic range and frequency selectivity. A decades-old hypothesis proposes that slow adaptation requires myosin motors to modulate the tip-link position on taller stereocilia. This "motor model" depended on data suggesting that the receptor current decay had a time course similar to that of hair-bundle creep (a continued movement in the direction of a step-like force stimulus). Using cochlear and vestibular hair cells of mice, rats, and gerbils, we assessed how modulating adaptation affected hair-bundle creep. Our results are consistent with slow adaptation requiring myosin motors. However, the hair-bundle creep and slow adaptation were uncorrelated, challenging a critical piece of evidence upholding the motor model. Considering these data, we propose a revised model of hair cell adaptation., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Mutations in myosin-VIIa (MYO7A) cause Usher syndrome type 1, characterized by combined deafness and blindness. MYO7A is proposed to function as a motor that tensions the hair cell mechanotransduction (MET) complex, but conclusive evidence is lacking. Here we report that multiple MYO7A isoforms are expressed in the mouse cochlea. In mice with a specific deletion of the canonical isoform (Myo7a-ΔC mouse), MYO7A is severely diminished in inner hair cells (IHCs), while expression in outer hair cells is affected tonotopically. IHCs of Myo7a-ΔC mice undergo normal development, but exhibit reduced resting open probability and slowed onset of MET currents, consistent with MYO7A's proposed role in tensioning the tip link. Mature IHCs of Myo7a-ΔC mice degenerate over time, giving rise to progressive hearing loss. Taken together, our study reveals an unexpected isoform diversity of MYO7A expression in the cochlea and highlights MYO7A's essential role in tensioning the hair cell MET complex.

Objectives: This study thoroughly explored the demographic and imaging characteristics, as well as the all-cause and cause-specific mortality risks of patients with a coronary artery calcium (CAC) score ≥1,000 in the largest dataset of this population to date., Background: CAC is commonly used to quantify cardiovascular risk. Current guidelines classify a CAC score of >300 or 400 as the highest risk group, yet little is known about the potentially unique imaging characteristics and mortality risk in individuals with a CAC score ≥1,000., Methods: A total of 66,636 asymptomatic adults were included from the CAC consortium, a large retrospective multicenter clinical cohort. Mean patient follow-up was 12.3 ± 3.9 years for patients with cardiovascular disease (CVD), coronary heart disease (CHD), cancer, and all-cause mortality. Multivariate Cox proportional hazards regression models adjusted for age, sex, and conventional risk factors were used to assess the relative mortality hazard of individuals with CAC ≥1,000 compared with, first, a CAC reference of 0, and second, with patients with a CAC score of 400 to 999., Results: There were 2,869 patients with CAC ≥1,000 (86.3% male, mean 66.3 ± 9.7 years of age). Most patients with CAC ≥1,000 had 4-vessel CAC (mean: 3.5 ± 0.6 vessels) and had greater total CAC area, higher mean CAC density, and more extracoronary calcium (79% with thoracic artery calcium, 46% with aortic valve calcium, and 21% with mitral valve calcium) than those with CAC scores of 400 to 999. After full adjustment, those with CAC ≥1,000 had a 5.04- (95% confidence interval [CI]: 3.92 to 6.48), 6.79- (95% CI: 4.74 to 9.73), 1.55- (95% CI:1.23 to 1.95), and 2.89-fold (95% CI: 2.53 to 3.31) risk of CVD, CHD, cancer, and all-cause mortality, respectively, compared to those with CAC score of 0. The CAC ≥1,000 group had a 1.71- (95% CI: 1.41 to 2.08), 1.84- (95% CI: 1.43 to 2.36), 1.36- (95% CI:1.07 to 1.73), and 1.51-fold (95% CI: 1.33 to 1.70) increased risk of CVD, CHD, cancer, and all-cause mortality compared to those with CAC scores 400 to 999. Graphic analysis of CAC ≥1,000 patients revealed continued logarithmic increase in risk, with no clear evidence of a risk plateau., Conclusions: Patients with extensive CAC (CAC ≥1,000) represent a unique very high-risk phenotype with mortality outcomes commensurate with high-risk secondary prevention patients. Future guidelines should consider CAC ≥1,000 patients to be a distinct risk group who may benefit from the most aggressive preventive therapy., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Sound detection in auditory sensory hair cells depends on the deflection of the stereocilia hair bundle which opens mechano-electric transduction (MET) channels. Adaptation is hypothesized to be a critical property of MET that contributes to the auditory system's wide dynamic range and sharp frequency selectivity. Our recent work using a stiff probe to displace hair bundles showed that the fastest adaptation mechanism (fast adaptation) does not require calcium entry. Using fluid-jet stimuli, others obtained data showing only a calcium-dependent fast adaptation response. Because cochlear stereocilia do not move coherently and the hair cell response depends critically on the magnitude and time course of the hair bundle deflection, we developed a high-speed imaging technique to quantify this deflection in rat cochlear hair cells. The fluid jet delivers a force stimulus, and force steps lead to a complex time course of hair bundle displacement (mechanical creep), which affects the hair cell's macroscopic MET current response by masking the time course of the fast adaptation response. Modifying the fluid-jet stimulus to generate a hair bundle displacement step produced rapidly adapting currents that did not depend on membrane potential, confirming that fast adaptation does not depend on calcium entry. MET current responses differ with stimulus modality and will shape receptor potentials of different hair cell types based on their in vivo stimulus mode. These transformations will directly affect how stimuli are encoded. SIGNIFICANCE STATEMENT Mechanotransduction by sensory hair cells represents a key first step for the sound sensing ability in vertebrates. The sharp frequency tuning and wide dynamic range of sound sensation are hypothesized to require a mechanotransduction adaptation mechanism. Recent work indicated that the apparent calcium dependence of the fastest adaptation differs with the method of cochlear hair cell stimulation. Here, we reconcile existing data and show that calcium entry does not drive the fastest adaptation process, independent of the stimulation method. With force stimulation of the hair bundle, adaptation manifests differently than with displacement stimulation, indicating that the stimulation mode of the hair bundle will affect the hair cell receptor current and stimulus coding., (Copyright © 2019 the authors.)

Introduction: Bloating is one of the most common gastrointestinal complaints. Evidence has linked fiber and sodium to bloating; however, randomized trials examining these diet components are lacking. Here, we used a randomized trial to examine the effects of the high-fiber DASH diet and dietary sodium intake on abdominal bloating. We hypothesized that both the high-fiber DASH diet and higher sodium intake would increase bloating., Methods: The DASH-Sodium trial (1998-1999) randomized healthy adults to a high-fiber (32 g/d) DASH or low-fiber (11 g/d) Western diet (control). On their assigned diet, participants ate 3 sodium levels (50, 100, and 150 mmol/d at 2100 kcal) in 30-day periods in random order, with 5-day breaks between each period. The participants reported the presence of bloating at baseline and after each feeding period. Statistical analyses included log-binomial models to evaluate the risk of bloating., Results: Of 412 participants (mean age 48 years; 57% women; 57% black), 36.7% reported bloating at baseline. Regardless of the diet, high sodium intake increased the risk of bloating (risk ratio = 1.27; 95% confidence interval: 1.06-1.52; P = 0.01). The high-fiber DASH diet also increased the risk of bloating over all sodium levels (risk ratio = 1.41; 95% confidence interval: 1.22-1.64; P < 0.001). The effect of high-fiber DASH on bloating was greater in men than in women (P for interaction = 0.001)., Discussion: Higher dietary sodium increased bloating, as did the high-fiber DASH diet. Although healthful high-fiber diets may increase bloating, these effects may be partially mitigated by decreasing dietary sodium intake. Future research is needed to explore mechanisms by which sodium intake and diet can influence bloating.

Allosteric ligands modulate protein activity by altering the energy landscape of conformational space in ligand-protein complexes. Here we investigate how ligand binding to a K + channel's voltage sensor allosterically modulates opening of its K + -conductive pore. The tarantula venom peptide guangxitoxin-1E (GxTx) binds to the voltage sensors of the rat voltage-gated K + (Kv) channel Kv2.1 and acts as a partial inverse agonist. When bound to GxTx, Kv2.1 activates more slowly, deactivates more rapidly, and requires more positive voltage to reach the same K + -conductance as the unbound channel. Further, activation kinetics are more sigmoidal, indicating that multiple conformational changes coupled to opening are modulated. Single-channel current amplitudes reveal that each channel opens to full conductance when GxTx is bound. Inhibition of Kv2.1 channels by GxTx results from decreased open probability due to increased occurrence of long-lived closed states; the time constant of the final pore opening step itself is not impacted by GxTx. When intracellular potential is less than 0 mV, GxTx traps the gating charges on Kv2.1's voltage sensors in their most intracellular position. Gating charges translocate at positive voltages, however, indicating that GxTx stabilizes the most intracellular conformation of the voltage sensors (their resting conformation). Kinetic modeling suggests a modulatory mechanism: GxTx reduces the probability of voltage sensors activating, giving the pore opening step less frequent opportunities to occur. This mechanism results in K + -conductance activation kinetics that are voltage-dependent, even if pore opening (the rate-limiting step) has no inherent voltage dependence. We conclude that GxTx stabilizes voltage sensors in a resting conformation, and inhibits K + currents by limiting opportunities for the channel pore to open, but has little, if any, direct effect on the microscopic kinetics of pore opening. The impact of GxTx on channel gating suggests that Kv2.1's pore opening step does not involve movement of its voltage sensors., (© 2019 Tilley et al.)

Lightheadedness after standing contributes to adverse clinical events, including falls. Recommendations for higher sodium intake to treat postural lightheadedness have not been evaluated in a trial setting. The Dietary Approaches to Stop Hypertension (DASH)-Sodium trial (1998-1999) tested the effects of the DASH diet and sodium reduction on blood pressure (BP). Participants were randomly assigned to DASH or a typical Western diet (control). During either diet, participants ate three sodium levels (50, 100, 150 meq/d at 2100 kcal) in random order for 30-days, separated by 5-day breaks. Participants reported the presence and severity of postural lightheadedness at baseline and after each feeding period. There were 412 participants (mean age 48 years; 57% women; 57% black). Mean baseline SBP/DBP was 135/86 mm Hg; 9.5% reported baseline lightheadedness. Among those consuming the DASH diet, high vs low sodium increased lightheadedness (OR 1.71; 95% CI: 1.01, 2.90; P = 0.047) and severity of lightheadedness (P = 0.02), but did not affect lightheadedness in those consuming the control diet (OR 0.77; 95% CI: 0.46, 1.29; P = 0.32). Among those consuming high vs low sodium in the context of the DASH diet, adults <60 vs ≥60 years old experienced more lightheadedness (P-interaction = 0.04), along with obese vs non-obese adults (P-interaction = 0.01). In the context of the DASH diet, higher sodium intake was associated with more frequent and severe lightheadedness. These findings challenge traditional recommendations to increase sodium intake to prevent lightheadedness., (©2019 Wiley Periodicals, Inc.)

Introduction: The new kidney allocation system (KAS) prioritizes patients based on date of dialysis initiation or waitlisting, whichever is earlier. We hypothesized that this change would increase transplant rates for patients with prolonged pretransplant dialysis times (DT) and aimed to assess the impact of prolonged DT on post-transplant outcomes., Methods: We used United Network for Organ Sharing registry data to assess outcomes for patients added to the renal transplant waitlist from January 1, 1998 to December 31, 2010 and patients transplanted from January 1, 1998 to December 3, 2012., Results: Compared with patients transplanted pre-emptively, patients with <5 years, 5-9 years, and ≥10 years DT had progressively decreased graft and patient survival (P < .001). The rates of short-term complications including delayed graft function, graft loss within 30 days, and patient death within 30 days were significantly higher in cohorts with ≥10 years DT than in cohorts with less DT (P < .001)., Conclusions: Patients with pretransplant DT of ≥10 years had worse outcomes than patients pre-emptively transplanted or transplanted with shorter DT. Durations of dialysis dependence beyond 10 years were associated with further deterioration in short-term but not long-term post-transplant outcomes., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Kidney Allocation System (KAS) was enacted in 2014 to improve graft utility, while facilitating transplantation of highly-sensitized patients and preserving pediatric access to high-quality kidneys. Central to this system is the Kidney Donor Profile Index (KDPI), a metric intended to predict transplant outcomes based on donor characteristics but derived using only adult donors. We posited that KAS had inadvertently altered the profile and quantity of kidneys made available to pediatric recipients. This question arose from our observation that most pediatric donors carry a KDPI over 35 and have therefore been rendered relatively inaccessible to pediatric recipients under KAS. Here we explore early trends in pediatric transplantation following KAS, including: (i) use of pediatric donors, (ii) use of Public Health System (PHS) high infectious risk donors, (iii) wait time, and (iv) living donor transplantation. We note some concerning preliminary changes following KAS implementation, including the allocation of fewer deceased donor pediatric kidneys to children and stagnation in pediatric wait times. Moreover, the poor predictive power of the KDPI for adult donors appears to be even worse when applied to pediatric donors. These early trends warrant further observation and consideration of changes in pediatric kidney allocation if they persist., (© 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Membrane proteins, such as ion channels, interact dynamically with their lipid environment. Phosphoinositol-4,5-bisphosphate (PIP 2 ) can directly or indirectly modify ion-channel properties. In auditory sensory hair cells of rats (Sprague Dawley) of either sex, PIP 2 localizes within stereocilia, near stereocilia tips. Modulating the amount of free PIP 2 in inner hair-cell stereocilia resulted in the following: (1) the loss of a fast component of mechanoelectric-transduction current adaptation, (2) an increase in the number of channels open at the hair bundle's resting position, (3) a reduction of single-channel conductance, (4) a change in ion selectivity, and (5) a reduction in calcium pore blocking effects. These changes occur without altering hair-bundle compliance or the number of functional stereocilia within a given hair bundle. Although the specific molecular mechanism for PIP 2 action remains to be uncovered, data support a hypothesis for PIP 2 directly regulating channel conformation to alter calcium permeation and single-channel conductance. SIGNIFICANCE STATEMENT How forces are relayed to the auditory mechanoelectrical transduction (MET) channel remains unknown. However, researchers have surmised that lipids might be involved. Previous work on bullfrog hair cells showed an effect of phosphoinositol-4,5-bisphosphate (PIP 2 ) depletion on MET current amplitude and adaptation, leading to the postulation of the existence of an underlying myosin-based adaptation mechanism. We find similar results in rat cochlea hair cells but extend these data to include single-channel analysis, hair-bundle mechanics, and channel-permeation properties. These additional data attribute PIP 2 effects to actions on MET-channel properties and not motor interactions. Further findings support PIP 2 's role in modulating a fast, myosin-independent, and Ca 2+ -independent adaptation process, validating fast adaptation's biological origin. Together this shows PIP 2 's pivotal role in auditory MET, likely as a direct channel modulator., (Copyright © 2017 the authors 0270-6474/17/3711632-15$15.00/0.)

Early studies of national data suggest that the Share 35 allocation policy increased liver transplants without compromising posttransplant outcomes. Changes in center-specific volumes and practice patterns in response to the national policy change are not well characterized. Understanding center-level responses to Share 35 is crucial for optimizing the policy and constructing effective future policy revisions. Data from the United Network for Organ Sharing were analyzed to compare center-level volumes of allocation-Model for End-Stage Liver Disease (aMELD) ≥ 35 transplants before and after policy implementation. There was significant center-level variation in the number and proportion of aMELD ≥ 35 transplants performed from the pre- to post-Share 35 period; 8 centers accounted for 33.7% of the total national increase in aMELD ≥ 35 transplants performed in the 2.5-year post-Share 35 period, whereas 25 centers accounted for 65.0% of the national increase. This trend correlated with increased listing at these centers of patients with Model for End-Stage Liver Disease (MELD) ≥ 35 at the time of initial listing. These centers did not overrepresent the total national volume of liver transplants. Comparison of post-Share 35 aMELD to calculated time-of-transplant (TOT) laboratory MELD scores showed that only 69.6% of patients transplanted with aMELD ≥ 35 maintained a calculated laboratory MELD ≥ 35 at the TOT. In conclusion, Share 35 increased transplantation of aMELD ≥ 35 recipients on a national level, but the policy asymmetrically impacted practice patterns and volumes of a subset of centers. Longer-term data are necessary to assess outcomes at centers with markedly increased volumes of high-MELD transplants after Share 35. Liver Transplantation 23 741-750 2017 AASLD., (© 2017 by the American Association for the Study of Liver Diseases.)

Mutations in the Pejvakin ( PJVK ) gene are thought to cause auditory neuropathy and hearing loss of cochlear origin by affecting noise-induced peroxisome proliferation in auditory hair cells and neurons. Here we demonstrate that loss of pejvakin in hair cells, but not in neurons, causes profound hearing loss and outer hair cell degeneration in mice. Pejvakin binds to and colocalizes with the rootlet component TRIOBP at the base of stereocilia in injectoporated hair cells, a pattern that is disrupted by deafness-associated PJVK mutations. Hair cells of pejvakin-deficient mice develop normal rootlets, but hair bundle morphology and mechanotransduction are affected before the onset of hearing. Some mechanotransducing shorter row stereocilia are missing, whereas the remaining ones exhibit overextended tips and a greater variability in height and width. Unlike previous studies of Pjvk alleles with neuronal dysfunction, our findings reveal a cell-autonomous role of pejvakin in maintaining stereocilia architecture that is critical for hair cell function. SIGNIFICANCE STATEMENT Two missense mutations in the Pejvakin ( PJVK or DFNB59 ) gene were first identified in patients with audiological hallmarks of auditory neuropathy spectrum disorder, whereas all other PJVK alleles cause hearing loss of cochlear origin. These findings suggest that complex pathogenetic mechanisms underlie human deafness DFNB59. In contrast to recent studies, we demonstrate that pejvakin in auditory neurons is not essential for normal hearing in mice. Moreover, pejvakin localizes to stereociliary rootlets in hair cells and is required for stereocilia maintenance and mechanosensory function of the hair bundle. Delineating the site of the lesion and the mechanisms underlying DFNB59 will allow clinicians to predict the efficacy of different therapeutic approaches, such as determining compatibility for cochlear implants., (Copyright © 2017 the authors 0270-6474/17/373447-18$15.00/0.)

The auditory system is able to detect movement down to atomic dimensions. This sensitivity comes in part from mechanisms associated with gating of hair cell mechanoelectric transduction (MET) channels. MET channels, located at the tops of stereocilia, are poised to detect tension induced by hair bundle deflection. Hair bundle deflection generates a force by pulling on tip-link proteins connecting adjacent stereocilia. The resting open probability (P(open)) of MET channels determines the linearity and sensitivity to mechanical stimulation. Classically, P(open) is regulated by a calcium-sensitive adaptation mechanism in which lowering extracellular calcium or depolarization increases P(open). Recent data demonstrated that the fast component of adaptation is independent of both calcium and voltage, thus requiring an alternative explanation for the sensitivity of P(open) to calcium and voltage. Using rat auditory hair cells, we characterize a mechanism, separate from fast adaptation, whereby divalent ions interacting with the local lipid environment modulate resting P(open). The specificity of this effect for different divalent ions suggests binding sites that are not an EF-hand or calmodulin model. GsMTx4, a lipid-mediated modifier of cationic stretch-activated channels, eliminated the voltage and divalent sensitivity with minimal effects on adaptation. We hypothesize that the dual mechanisms (lipid modulation and adaptation) extend the dynamic range of the system while maintaining adaptation kinetics at their maximal rates., (Copyright © 2016 the authors 0270-6474/16/362945-12$15.00/0.)

Hair cells are designed to sense mechanical stimuli of sound using their apical stereocilia hair bundles. Mechanical deflection of this hair bundle is converted into an electrical signal through gating of mechano-electric transduction channels. Stiff probe stimulation of hair bundles is an invaluable tool for studying the transduction channel and its associated processes because of the speed and ability to precisely control hair bundle position. Proper construction of these devices is critical to their ultimate performance as is appropriate placement of the probe onto the hair bundle. Here we describe the construction and use of a glass probe coupled to a piezo-electric actuator for stimulating hair bundles, including the basic technique for positioning of the stimulating probe onto the hair bundle. These piezo-electric stimulators can be adapted to other mechanically sensitive systems.

Current-displacement (I-X) and the force-displacement (F-X) relationships characterize hair-cell mechano-transduction in the inner ear. A common technique for measuring these relationships is to deliver mechanical stimulations to individual hair bundles with microprobes and measure whole cell transduction currents through patch pipette electrodes at the basolateral membrane. The sensitivity of hair-cell mechano-transduction is determined by two fundamental biophysical properties of the mechano-transduction channel, the stiffness of the putative gating spring and the gating swing, which are derived from the I-X and F-X relationships. Although the hair-cell stereocilia in vivo deflect <100 nm even at high sound pressure levels, often it takes >500 nm of stereocilia displacement to saturate hair-cell mechano-transduction in experiments with individual hair cells in vitro. Despite such discrepancy between in vivo and in vitro data, key biophysical properties of hair-cell mechano-transduction to define the transduction sensitivity have been estimated from in vitro experiments. Using three-dimensional finite-element methods, we modeled an inner hair-cell and an outer hair-cell stereocilia bundle and simulated the effect of probe stimulation. Unlike the natural situation where the tectorial membrane stimulates hair-cell stereocilia evenly, probes deflect stereocilia unevenly. Because of uneven stimulation, 1) the operating range (the 10-90% width of the I-X relationship) increases by a factor of 2-8 depending on probe shapes, 2) the I-X relationship changes from a symmetric to an asymmetric function, and 3) the bundle stiffness is underestimated. Our results indicate that the generally accepted assumption of parallel stimulation leads to an overestimation of the gating swing and underestimation of the gating spring stiffness by an order of magnitude., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Adaptation is a hallmark of hair cell mechanotransduction, extending the sensory hair bundle dynamic range while providing mechanical filtering of incoming sound. In hair cells responsive to low frequencies, two distinct adaptation mechanisms exist, a fast component of debatable origin and a slow myosin-based component. It is generally believed that Ca(2+) entry through mechano-electric transducer channels is required for both forms of adaptation. This study investigates the calcium dependence of adaptation in the mammalian auditory system. Recordings from rat cochlear hair cells demonstrate that altering Ca(2+) entry or internal Ca(2+) buffering has little effect on either adaptation kinetics or steady-state adaptation responses. Two additional findings include a voltage-dependent process and an extracellular Ca(2+) binding site, both modulating the resting open probability independent of adaptation. These data suggest that slow motor adaptation is negligible in mammalian auditory cells and that the remaining adaptation process is independent of calcium entry., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Understanding the mechanisms responsible for our sense of hearing requires new tools for unprecedented stimulation and monitoring of sensory cell mechanotransduction at frequencies yet to be explored. We describe nanomechanical force probes designed to evoke mechanotransduction currents at up to 100 kHz in living cells. High-speed force and displacement metrology is enabled by integrating piezoresistive sensors and piezoelectric actuators onto nanoscale cantilevers. The design, fabrication process, actuator performance, and actuator-sensor crosstalk compensation results are presented. We demonstrate the measurement of mammalian cochlear hair cell mechanotransduction with simultaneous patch clamp recordings at unprecedented speeds. The probes can deliver mechanical stimuli with sub-10 μs rise times in water and are compatible with standard upright and inverted microscopes.

Confocal fluorescence microscopy is a broadly used imaging technique that enhances the signal-to-noise ratio by removing out of focal plane fluorescence. Confocal microscopes come with a variety of modifications depending on the particular experimental goals. Microscopes, illumination pathways, and light collection were originally focused upon obtaining the highest resolution image possible, typically on fixed tissue. More recently, live-cell confocal imaging has gained importance. Since measured signals are often rapid or transient, thus requiring higher sampling rates, specializations are included to enhance spatial and temporal resolution while maintaining tissue viability. Thus, a balance between image quality, temporal resolution, and tissue viability is needed. A subtype of confocal imaging, termed swept field confocal (SFC) microscopy, can image live cells at high rates while maintaining confocality. SFC systems can use a pinhole array to obtain high spatial resolution, similar to spinning disc systems. In addition, SFC imaging can achieve faster rates by using a slit to sweep the light across the entire image plane, thus requiring a single scan to generate an image. Coupled to a high-speed charge-coupled device camera and a laser illumination source, images can be obtained at greater than 1,000 frames per second while maintaining confocality.

Mechanosensation is a primitive and somewhat ubiquitous sense. At the inner ear, sensory hair cells are refined to enhance sensitivity, dynamic range and frequency selectivity. Thirty years ago, mechanisms of mechanotransduction and adaptation were well accounted for by simple mechanical models that incorporated physiological and morphological properties of hair cells. Molecular and genetic tools, coupled with new optical techniques, are now identifying and localizing specific components of the mechanotransduction machinery. These new findings challenge long-standing theories, and require modification of old and development of new models. Future advances require the integration of molecular and physiological data to causally test these new hypotheses.

Hearing organs have evolved to detect sounds across several orders of magnitude of both intensity and frequency. Detection limits are at the atomic level despite the energy associated with sound being limited thermodynamically. Several mechanisms have evolved to account for the remarkable frequency selectivity, dynamic range, and sensitivity of these various hearing organs, together termed the active process or cochlear amplifier. Similarities between hearing organs of disparate species provides insight into the factors driving the development of the cochlear amplifier. These properties include: a tonotopic map, the emergence of a two hair cell system, the separation of efferent and afferent innervations, the role of the tectorial membrane, and the shift from intrinsic tuning and amplification to a more end organ driven process. Two major contributors to the active process are hair bundle mechanics and outer hair cell electromotility, the former present in all hair cell organs tested, the latter only present in mammalian cochlear outer hair cells. Both of these processes have advantages and disadvantages, and how these processes interact to generate the active process in the mammalian system is highly disputed. A hypothesis is put forth suggesting that hair bundle mechanics provides amplification and filtering in most hair cells, while in mammalian cochlea, outer hair cell motility provides the amplification on a cycle by cycle basis driven by the hair bundle that provides frequency selectivity (in concert with the tectorial membrane) and compressive nonlinearity. Separating components of the active process may provide additional sites for regulation of this process., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Mechanosensitive sensory hair cells are the linchpin of our senses of hearing and balance. The inability of the mammalian inner ear to regenerate lost hair cells is the major reason for the permanence of hearing loss and certain balance disorders. Here, we present a stepwise guidance protocol starting with mouse embryonic stem and induced pluripotent stem cells, which were directed toward becoming ectoderm capable of responding to otic-inducing growth factors. The resulting otic progenitor cells were subjected to varying differentiation conditions, one of which promoted the organization of the cells into epithelial clusters displaying hair cell-like cells with stereociliary bundles. Bundle-bearing cells in these clusters responded to mechanical stimulation with currents that were reminiscent of immature hair cell transduction currents., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Inner ear sensory hair cells convert mechanical stimuli into electrical signals. This conversion happens in the exquisitely mechanosensitive hair bundle that protrudes from the cell's apical surface. In mammals, cochlear hair bundles are composed of 50-100 actin-filled stereocilia, which are organized in three rows in a staircase manner. Stereocilia actin filaments are uniformly oriented with their barbed ends toward stereocilia tips. During development, the actin core of each stereocilium undergoes elongation due to addition of actin monomers to the barbed ends of the filaments. Here we show that in the mouse cochlea the barbed end capping protein twinfilin 2 is present at the tips of middle and short rows of stereocilia from postnatal day 5 (P5) onward, which correlates with a time period when these rows stop growing. The tall stereocilia rows, which do not display twinfilin 2 at their tips, continue to elongate between P5 and P15. When we expressed twinfilin 2 in LLC/PK1-CL4 (CL4) cells, we observed a reduction of espin-induced microvilli length, pointing to a potent function of twinfilin 2 in suppressing the elongation of actin filaments. Overexpression of twinfilin 2 in cochlear inner hair cells resulted in a significant reduction of stereocilia length. Our results suggest that twinfilin 2 plays a role in the regulation of stereocilia elongation by restricting excessive elongation of the shorter row stereocilia thereby maintaining the mature staircase architecture of cochlear hair bundles.

Inner ear hair-cell mechanoelectrical transduction is mediated by a largely unidentified multiprotein complex associated with the stereociliary tips of hair bundles. One identified component of tip links, which are the extracellular filamentous connectors implicated in gating the mechanoelectrical transduction channels, is the transmembrane protein cadherin 23 (Cdh23), more specifically, the hair- cell-specific Cdh23(+68) splice variant. Using the intracellular domain of Cdh23(+68) as bait, we identified in a cochlear cDNA library MAGI-1, a MAGUK (membrane-associated guanylate kinase) protein. MAGI-1 binds via its PDZ4 domain to a C-terminal PDZ-binding site on Cdh23. MAGI-1 immunoreactivity was detectable throughout neonatal stereocilia in a distribution similar to that of Cdh23. As development proceeded, MAGI-1 occurred in a punctate staining pattern on stereocilia, which was maintained into adulthood. Previous reports suggest that Cdh23 interacts via an internal PDZ-binding site with the PDZ1 domain of the stereociliary protein harmonin, and potentially via a weaker binding of its C terminus with harmonin's PDZ2 domain. We propose that MAGI-1 has the ability to replace harmonin's PDZ2 binding at Cdh23's C terminus. Moreover, the strong interaction between PDZ1 of harmonin and Cdh23 is interrupted by a 35 aa insertion in the hair-cell-specific Cdh23(+68) splice variant, which puts forward MAGI-1 as an attractive candidate for an intracellular scaffolding partner of this tip-link protein. Our results consequently support a role of MAGI-1 in the tip-link complex, where it could provide a sturdy connection with the cytoskeleton and with other components of the mechanoelectrical transduction complex.

In a single-center, randomized study, zanamivir (Relenza) concentrations in induced sputum samples and nasal washings of healthy adults following oral inhalation were measured. Concentrations in sputum exceeded the median viral neuraminidase 50% inhibitory concentration at 6, 12, and 24 h, and those in nasal washings did so at 6 and 12 h. There were no zanamivir-related adverse events or laboratory abnormalities.

The pharmacokinetics of zanamivir were evaluated in subjects from three phase I single-center and two phase II multicenter, randomized, double-blind, multidose, placebo-controlled trials. A total of 96 phase I subjects received zanamivir (3.6 to 16 mg) intranasally two or six times daily for 4 to 5 days beginning 4 hours before or 1 to 2 days after inoculation with influenza virus. A total of 75 phase II subjects with influenza or a history of exposure to naturally occurring influenza virus were administered zanamivir as an intranasal spray (3.4 mg/nostril), inhaled powder (10 mg), or combination of intranasal and inhaled formulations twice daily for 5 days. Population parameters (including demographic factors, zanamivir formulation, infection-related variables, and concurrent medication use) were estimated by a nonlinear mixed-effect modeling software program (NONMEM) using a one-compartment model with first-order absorption and conditional estimation algorithm. Formulation and route of administration were the most significant factors affecting the pharmacokinetics of zanamivir. Relative bioavailability of the inhaled powder to the intranasal drops and spray was 2.3 and 1.6, respectively. No significant differences in pharmacokinetic parameters were observed when demographic variables, indices of infection, or concurrent medication use were considered in either phase I or phase II population analyses.

The local immune response to influenza virus infection was characterized by determining cytokine and chemokine levels in serial nasal lavage fluid samples from 15 volunteers experimentally infected with influenza A/Texas/36/91 (H1N1). The study was part of a randomized double-blind placebo-controlled trial to determine the prophylactic effect of intravenous zanamivir (600 mg 2x/day for 5 days), a highly selective inhibitor of influenza A and B virus neuraminidases, on the clinical symptoms of influenza infection. Nasal lavage fluid levels of interleukin (IL)-6, tumor necrosis factor-alpha, interferon-gamma, IL-10, monocyte chemotactic protein-1, and macrophage inflammatory protein-1alpha and -1beta increased in response to influenza virus infection and correlated statistically with the magnitude and time course of the symptoms. Treatment with zanamivir prevented the infection and abrogated the local cytokine and chemokine responses. These results reveal a complex interplay of cytokines and chemokines in the development of symptoms and resolution of influenza.

Zanamivir is a potent inhibitor of influenza A and B virus neuraminidases and is active topically in experimental and natural human influenza. We conducted this double-blinded, placebo-controlled study to evaluate the safety and efficacy of intravenously administered zanamivir. Susceptible volunteers were randomized to receive either saline or zanamivir (600 mg) intravenously twice daily for 5 days beginning 4 h prior to intranasal inoculation with approximately 10(5) 50% tissue culture infectious doses (TCID50) of influenza A/Texas/36/91 (H1N1) virus. Reductions in the frequency of viral shedding (0% versus 100% in placebo, P < 0.005) and seroconversion (14% versus 100% in placebo, P < 0.005) and decreases in viral titer areas under the curve (0 versus 11.6 [median] log10 TCID50. day/ml in placebo, P < 0.005) were observed in the zanamivir group, as were reductions in fever (14% versus 88% in placebo, P < 0.05), upper respiratory tract illness (0% versus 100% in placebo, P < 0.005), total symptom scores (1 versus 44 [median] in placebo, P < 0.005), and nasal-discharge weight (3.9 g versus 17.5 g [median] in placebo, P < 0.005). Zanamivir was detectable in nasal lavage samples collected on days 2 and 4 (unadjusted median concentrations, 10.5 and 12.0 ng/ml of nasal wash, respectively). This study demonstrates that intravenously administered zanamivir is distributed to the respiratory mucosa and is protective against infection and illness following experimental human influenza A virus inoculation.

Zanamivir, a potent inhibitor of influenza A and B virus neuraminidases, is protective against experimental human influenza when given intranasally twice daily. We conducted two studies to assess the pharmacokinetics and protective efficacy of a reduced frequency dosing regimen of topical zanamivir. In the first study, 36 uninfected volunteers received a single dose of zanamivir by intranasal spray (6.4 mg), intranasal drops (16 mg) or dry powder oral inhalation (10 mg). At 4 h, median nasal wash concentrations were 50-fold higher after intranasal dosing than after inhalation. Substantial levels (spray group, median 4,596 ng/ml; drop group, 1,239 ng/ml) were detected in nasal wash 48 h after intranasal dosing. In the double-blinded efficacy study, 47 sero-susceptible volunteers were randomized to receive either placebo or zanamivir intranasal spray (6.4 mg). Among the 43 subjects evaluated, decreases in viral shedding occurred in the group receiving one dose of zanamivir 4 h prior to inoculation, whereas no significant benefit was observed in those receiving a single dose 48 h prior to challenge. In the group given three daily doses, reductions were seen in viral shedding and infection. In the two regimens providing zanamivir 4 h prior to inoculation, significant reductions in nasal mucus weight were observed. Decreases in total symptom scores and the incidence of upper respiratory illness also occurred, but they did not reach statistical significance. The efficacy of a single dose of zanamivir given 4 h prior to inoculation supports the hypothesis that influenza virus neuraminidase is essential for initial virus spread through respiratory secretions. These findings indicate that once daily dosing of zanamivir is protective against experimental influenza A infection.

Remifentanil is a new, esterase-metabolized opioid for anesthesia. Nonspecific esterases terminate the drug effect, with a context-sensitive half-time which plateaus at 3-4 min. This dose-ranging pilot study was designed to estimate the dose requirement of remifentanil for abolition of the responses to skin incision and intraoperative stimuli, and to determine the speed of recovery. Fifty-one unpremedicated patients took part at two centers. Anesthesia was induced with propofol, 67% nitrous oxide, and vecuronium. Remifentanil was then given (1 microgram/kg, plus an infusion of 0.0125-1.0 micrograms.kg-1.min-1). Responses were defined as: > 15% increase in systolic blood pressure or > 20% increase in heart rate, tearing, sweating, movement, or coughing. Responses to incision or surgery were treated with 0.5 micrograms/kg remifentanil boluses and a 50% increase in infusion rate, which could be done twice. Subsequent responses were treated with propofol or isoflurane. Remifentanil and nitrous oxide administration were terminated after the incision was closed. ED50 for response to skin incision varied between the two study sites (0.020 and 0.087 microgram.kg-1.min-1). ED50 for response to all surgical stimuli was 0.52 microgram.kg-1.min-1. At 0.3 microgram.kg-1.min-1 or more, only 3 of 21 patients required isoflurane. Recovery was not longer in patients receiving larger doses to spontaneous ventilation (2.5-4.6 min), tracheal extubation (4.2-7.0 min), and response to verbal command (3.0-4.6 min). Postoperative pain was reported in most patients (92%) at a median time of 21 min. We conclude that remifentanil was effective and well tolerated as a component of nitrous oxide-opioid-relaxant anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)