SH2 domain protein E and ABL signaling regulate blood vessel size.

Blood vessels in different vascular beds vary in size, which is essential for their function and fluid flow along the vascular network. Molecular mechanisms involved in the formation of a vascular lumen of appropriate size, or tubulogenesis, are still only partially understood. Src homology 2 domain containing E (She) protein was previously identified in a screen for proteins that interact with Abelson (Abl)-kinase. However, its biological role has remained unknown. Here we demonstrate that She and Abl signaling regulate vessel size in zebrafish embryos and human endothelial cell culture. Zebrafish she mutants displayed increased endothelial cell number and enlarged lumen size of the dorsal aorta (DA) and defects in blood flow, eventually leading to the DA collapse. Vascular endothelial specific overexpression of she resulted in a reduced diameter of the DA, which correlated with the reduced arterial cell number and lower endothelial cell proliferation. Chemical inhibition of Abl signaling in zebrafish embryos caused a similar reduction in the DA diameter and alleviated the she mutant phenotype, suggesting that She acts as a negative regulator of Abl signaling. Enlargement of the DA size in she mutants correlated with an increased endothelial expression of claudin 5a (cldn5a), which encodes a protein enriched in tight junctions. Inhibition of cldn5a expression partially rescued the enlarged DA in she mutants, suggesting that She regulates DA size, in part, by promoting cldn5a expression. SHE knockdown in human endothelial umbilical vein cells resulted in a similar increase in the diameter of vascular tubes, and also increased phosphorylation of a known ABL downstream effector CRKL. These results argue that SHE functions as an evolutionarily conserved inhibitor of ABL signaling and regulates vessel and lumen size during vascular tubulogenesis.

EstimATTR: A Simplified, Machine-Learning-Based Tool to Predict the Risk of Wild-Type Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM), an increasingly recognized cause of heart failure (HF), often remains undiagnosed until later stages of the disease. METHODS AND RESULTS: A previously developed machine learning algorithm was simplified to create a random forest model based on 11 selected phenotypes predictive of ATTRwt-CM to estimate ATTRwt-CM risk in hypothetical patient scenarios. Using U.S. medical claims datasets (IQVIA), International Classification of Diseases codes were extracted to identify a training cohort of patients with ATTRwt-CM (cases) or nonamyloid HF (controls). After assessment in a 20% test sample of the training cohort, model performance was validated in cohorts of patients with International Classification of Diseases codes for ATTRwt-CM or cardiac amyloidosis vs nonamyloid HF derived from medical claims (IQVIA) or electronic health records (Optum). The simplified model performed well in identifying patients with ATTRwt-CM vs nonamyloid HF in the test sample, with an accuracy of 74%, sensitivity of 77%, specificity of 72%, and area under the curve of 0.82; robust performance was also observed in the validation cohorts. CONCLUSIONS: This simplified machine learning model accurately estimated the empirical probability of ATTRwt-CM in administrative datasets, suggesting it may serve as an easily implementable tool for clinical assessment of patient risk for ATTRwt-CM in the clinical setting. BRIEF LAY SUMMARY: Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM for short) is a frequently overlooked cause of heart failure. Finding ATTRwt-CM early is important because the disease can worsen rapidly without treatment. Researchers developed a computer program that predicts the risk of ATTRwt-CM in patients with heart failure. In this study, the program was used to check for 11 medical conditions linked to ATTRwt-CM in the medical claims records of patients with heart failure. The program was 74% accurate in identifying ATTRwt-CM in patients with heart failure and was then used to develop an educational online tool for doctors (the wtATTR-CM estimATTR).

SH2 domain protein E (SHE) and ABL signaling regulate blood vessel size.

Blood vessels in different vascular beds vary in lumen diameter, which is essential for their function and fluid flow along the vascular network. Molecular mechanisms involved in the formation of a vascular lumen of appropriate size, or tubulogenesis, are still only partially understood. Src homology 2 domain containing E (She) protein was previously identified in a screen for proteins that interact with Abelson (Abl)-kinase. However, its biological role has remained unknown. Here we demonstrate that She and Abl signaling regulate vascular lumen size in zebrafish embryos and human endothelial cell culture. Zebrafish she mutants displayed increased endothelial cell number and enlarged lumen size of the dorsal aorta (DA) and defects in blood flow. Vascular endothelial specific overexpression of she resulted in a reduced diameter of the DA lumen, which correlated with the reduced arterial cell number and lower endothelial cell proliferation. Chemical inhibition of Abl signaling in zebrafish embryos caused a similar reduction in the DA diameter and alleviated the she mutant phenotype, suggesting that She acts as a negative regulator of Abl signaling. Enlargement of the DA lumen in she mutants correlated with an increased endothelial expression of claudin 5a and 5b (cldn5a / cldn5b), which encode proteins enriched in tight junctions. Inhibition of cldn5a expression partially rescued the enlarged DA in she mutants, suggesting that She regulates DA lumen size, in part, by promoting cldn5a expression. SHE knockdown in human endothelial umbilical vein cells resulted in a similar increase in the diameter of vascular tubes, and also increased phosphorylation of a known ABL downstream effector CRKL. These results argue that SHE functions as an evolutionarily conserved inhibitor of ABL signaling and regulates lumen size during vascular tubulogenesis.

A machine learning model for identifying patients at risk for wild-type transthyretin amyloid cardiomyopathy.

Transthyretin amyloid cardiomyopathy, an often unrecognized cause of heart failure, is now treatable with a transthyretin stabilizer. It is therefore important to identify at-risk patients who can undergo targeted testing for earlier diagnosis and treatment, prior to the development of irreversible heart failure. Here we show that a random forest machine learning model can identify potential wild-type transthyretin amyloid cardiomyopathy using medical claims data. We derive a machine learning model in 1071 cases and 1071 non-amyloid heart failure controls and validate the model in three nationally representative cohorts (9412 cases, 9412 matched controls), and a large, single-center electronic health record-based cohort (261 cases, 39393 controls). We show that the machine learning model performs well in identifying patients with cardiac amyloidosis in the derivation cohort and all four validation cohorts, thereby providing a systematic framework to increase the suspicion of transthyretin cardiac amyloidosis in patients with heart failure.

Drug Discovery and Development in Rare Diseases: Taking a Closer Look at the Tafamidis Story.

Rare diseases are increasingly recognized as a global public health priority. Governments worldwide currently provide important incentives to stimulate the discovery and development of orphan drugs for the treatment of these conditions, but substantial scientific, clinical, and regulatory challenges remain. Tafamidis is a first-in-class, disease-modifying transthyretin (TTR) kinetic stabilizer that represents a major breakthrough in the treatment of transthyretin amyloidosis (ATTR amyloidosis). ATTR amyloidosis is a rare, progressive, and fatal systemic disorder caused by aggregation of misfolded TTR and extracellular deposition of amyloid fibrils in various tissues and organs, including the heart and nervous systems. In this review, we present the successful development of tafamidis spanning 3 decades, marked by meticulous laboratory research into disease mechanisms and natural history, and innovative clinical study design and implementation. These efforts established the safety and efficacy profile of tafamidis, leading to its regulatory approval, and enabled post-approval initiatives that further support patients with ATTR amyloidosis.

Integrin α5 and Integrin α4 cooperate to promote endocardial differentiation and heart morphogenesis.

Endocardium is critically important for proper function of the cardiovascular system. Not only does endocardium connect the heart to blood vasculature, it also plays an important role in heart morphogenesis, valve formation, and ventricular trabeculation. The extracellular protein Fibronectin (Fn1) promotes endocardial differentiation, but the signaling pathways downstream of Fn1 that regulate endocardial development are not understood. Here, we analyzed the role of the Fibronectin receptors Integrin alpha5 (Itga5) and Integrin alpha4 (Itga4) in zebrafish heart development. We show that itga5 mRNA is expressed in both endocardium and myocardium during early stages of heart development. Through analysis of both itga5 single mutants and itga4;itga5 double mutants, we show that loss of both itga5 and itga4 results in enhanced defects in endocardial differentiation and morphogenesis compared to loss of itga5 alone. Loss of both itga5 and itga4 results in cardia bifida and severe myocardial morphology defects. Finally, we find that loss of itga5 and itga4 results in abnormally narrow anterior endodermal sheet morphology. Together, our results support a model in which Itga5 and Itga4 cooperate to promote endocardial differentiation, medial migration of endocardial and myocardial cells, and morphogenesis of anterior endoderm.

Clec14a genetically interacts with Etv2 and Vegf signaling during vasculogenesis and angiogenesis in zebrafish.

BACKGROUND: C-lectin family 14 Member A (Clec14a) is a transmembrane protein specifically expressed in vascular endothelial cells during embryogenesis. Previous in vitro and in vivo studies have provided conflicting data regarding Clec14a role in promoting or inhibiting angiogenesis, therefore its functional role in vascular development remains poorly understood. RESULTS: Here we have generated a novel clec14a mutant allele in zebrafish embryos using TALEN genome editing. clec14a mutant embryos exhibit partial defects and delay in the sprouting of intersegmental vessels. These defects in angiogenesis are greatly increased upon the knockdown of a structurally related C1qr protein. Furthermore, a partial knockdown of an ETS transcription factor Etv2 results in a synergistic effect with the clec14a mutation and inhibits expression of early vascular markers in endothelial progenitor cells, arguing that clec14a is involved in promoting vasculogenesis. In addition, Clec14a genetically interacts with Vegfa signaling. A partial knockdown of Vegfaa function in the clec14a mutant background resulted in a synergistic inhibition of intersegmental vessel sprouting. CONCLUSIONS: These results argue that clec14a is involved in both vasculogenesis and angiogenesis, and suggest that Clec14a genetically interacts with Etv2 and Vegf signaling during vascular development in zebrafish embryos.

Tafamidis Treatment for Patients with Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Transthyretin amyloid cardiomyopathy is caused by the deposition of transthyretin amyloid fibrils in the myocardium. The deposition occurs when wild-type or variant transthyretin becomes unstable and misfolds. Tafamidis binds to transthyretin, preventing tetramer dissociation and amyloidogenesis. METHODS: In a multicenter, international, double-blind, placebo-controlled, phase 3 trial, we randomly assigned 441 patients with transthyretin amyloid cardiomyopathy in a 2:1:2 ratio to receive 80 mg of tafamidis, 20 mg of tafamidis, or placebo for 30 months. In the primary analysis, we hierarchically assessed all-cause mortality, followed by frequency of cardiovascular-related hospitalizations according to the Finkelstein-Schoenfeld method. Key secondary end points were the change from baseline to month 30 for the 6-minute walk test and the score on the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS), in which higher scores indicate better health status. RESULTS: In the primary analysis, all-cause mortality and rates of cardiovascular-related hospitalizations were lower among the 264 patients who received tafamidis than among the 177 patients who received placebo (P<0.001). Tafamidis was associated with lower all-cause mortality than placebo (78 of 264 [29.5%] vs. 76 of 177 [42.9%]; hazard ratio, 0.70; 95% confidence interval [CI], 0.51 to 0.96) and a lower rate of cardiovascular-related hospitalizations, with a relative risk ratio of 0.68 (0.48 per year vs. 0.70 per year; 95% CI, 0.56 to 0.81). At month 30, tafamidis was also associated with a lower rate of decline in distance for the 6-minute walk test (P<0.001) and a lower rate of decline in KCCQ-OS score (P<0.001). The incidence and types of adverse events were similar in the two groups. CONCLUSIONS: In patients with transthyretin amyloid cardiomyopathy, tafamidis was associated with reductions in all-cause mortality and cardiovascular-related hospitalizations and reduced the decline in functional capacity and quality of life as compared with placebo. (Funded by Pfizer; ATTR-ACT ClinicalTrials.gov number, NCT01994889 .).

Treatment With Tafamidis Slows Disease Progression in Early-Stage Transthyretin Cardiomyopathy.

BACKGROUND: Transthyretin cardiomyopathy (TTR-CM) is a progressive, fatal disease caused by the accumulation of misfolded transthyretin (TTR) amyloid fibrils in the heart. Tafamidis is a kinetic stabilizer of TTR that inhibits misfolding and amyloid formation. METHODS: In this post hoc analysis, data from an observational study (Transthyretin Amyloidosis Cardiac Study; n = 29) were compared with an open-label study of tafamidis in patients with TTR-CM (Fx1B-201; n = 35). To ensure comparable baseline disease severity, patients with New York Heart Association (NYHA) functional classification ≥III were excluded in this time-to-mortality analysis. RESULTS: Patients with either wild-type or Val122Ile genotypes treated with tafamidis have a significantly longer time to death compared with untreated patients (P = .0004). Similar results were obtained when limiting the analysis to wild-type patients only, without restricting NYHA functional classification (P = .0262). CONCLUSIONS: These results support earlier conclusions suggesting that tafamidis slows disease progression compared with no treatment outside of standard of care and warrant further investigation. TRIAL REGISTRATION: ClinicalTrials.gov, NCT00694161.

Vegf signaling promotes vascular endothelial differentiation by modulating etv2 expression.

Vasculogenesis involves the differentiation of vascular endothelial progenitors de novo from undifferentiated mesoderm, their migration and coalescence to form the major embryonic vessels and the acquisition of arterial or venous identity. Vascular Endothelial Growth Factor (Vegf) signaling plays multiple roles during vascular development. However, its function during embryonic vasculogenesis has been controversial. Previous studies have implicated Vegf signaling in either regulating arteriovenous specification or overall vascular endothelial differentiation. To clarify the role of Vegf in embryonic vasculogenesis and identify its downstream targets, we used chemical inhibitors of Vegf receptor (Vegfr) signaling in zebrafish embryos as well as zebrafish genetic mutants. A high level of chemical inhibition of Vegfr signaling resulted in the reduction of overall vascular endothelial marker gene expression, including downregulation of both arterial and venous markers, ultimately leading to the apoptosis of vascular endothelial cells. In contrast, a low level of Vegfr inhibition specifically blocked arterial specification while the expression of venous markers appeared largely unaffected or increased. Inhibition of Vegfr signaling prior to the initiation of vasculogenesis reduced overall vascular endothelial differentiation, while inhibition of Vegfr signaling starting at mid-somitogenesis stages largely inhibited arterial specification. Conversely, Vegf overexpression resulted in the expansion of both arterial and pan-endothelial markers, while the expression of several venous-specific markers was downregulated. We further show that Vegf signaling affects overall endothelial differentiation by modulating the expression of the ETS transcription factor etv2/ etsrp. etv2 expression was downregulated in Vegfr- inhibited embryos, and expanded in Vegfaa-overexpressing embryos. Furthermore, vascular-specific overexpression of etv2 in Vegfr-inhibited embryos rescued defects in vascular endothelial differentiation. Similarly, vegfaa genetic mutants displayed a combination of the two phenotypes observed with chemical Vegfr inhibition: the expression of arterial and pan-endothelial markers including etv2 was downregulated while the expression of most venous markers was either expanded or unchanged. Based on these results we propose a revised model which explains the different phenotypes observed upon inhibition of Vegf signaling: low levels of Vegf signaling promote overall vascular endothelial differentiation and cell survival by upregulating etv2 expression, while high levels of Vegf signaling promote arterial and inhibit venous specification.

SLO BK Potassium Channels Couple Gap Junctions to Inhibition of Calcium Signaling in Olfactory Neuron Diversification.

The C. elegans AWC olfactory neuron pair communicates to specify asymmetric subtypes AWCOFF and AWCON in a stochastic manner. Intercellular communication between AWC and other neurons in a transient NSY-5 gap junction network antagonizes voltage-activated calcium channels, UNC-2 (CaV2) and EGL-19 (CaV1), in the AWCON cell, but how calcium signaling is downregulated by NSY-5 is only partly understood. Here, we show that voltage- and calcium-activated SLO BK potassium channels mediate gap junction signaling to inhibit calcium pathways for asymmetric AWC differentiation. Activation of vertebrate SLO-1 channels causes transient membrane hyperpolarization, which makes it an important negative feedback system for calcium entry through voltage-activated calcium channels. Consistent with the physiological roles of SLO-1, our genetic results suggest that slo-1 BK channels act downstream of NSY-5 gap junctions to inhibit calcium channel-mediated signaling in the specification of AWCON. We also show for the first time that slo-2 BK channels are important for AWC asymmetry and act redundantly with slo-1 to inhibit calcium signaling. In addition, nsy-5-dependent asymmetric expression of slo-1 and slo-2 in the AWCON neuron is necessary and sufficient for AWC asymmetry. SLO-1 and SLO-2 localize close to UNC-2 and EGL-19 in AWC, suggesting a role of possible functional coupling between SLO BK channels and voltage-activated calcium channels in AWC asymmetry. Furthermore, slo-1 and slo-2 regulate the localization of synaptic markers, UNC-2 and RAB-3, in AWC neurons to control AWC asymmetry. We also identify the requirement of bkip-1, which encodes a previously identified auxiliary subunit of SLO-1, for slo-1 and slo-2 function in AWC asymmetry. Together, these results provide an unprecedented molecular link between gap junctions and calcium pathways for terminal differentiation of olfactory neurons.

Myocardium and BMP signaling are required for endocardial differentiation.

Endocardial and myocardial progenitors originate in distinct regions of the anterior lateral plate mesoderm and migrate to the midline where they coalesce to form the cardiac tube. Endocardial progenitors acquire a molecular identity distinct from other vascular endothelial cells and initiate expression of specific genes such as nfatc1. Yet the molecular pathways and tissue interactions involved in establishing endocardial identity are poorly understood. The endocardium develops in tight association with cardiomyocytes. To test for a potential role of the myocardium in endocardial morphogenesis, we used two different zebrafish models deficient in cardiomyocytes: the hand2 mutant and a myocardial-specific genetic ablation method. We show that in hand2 mutants endocardial progenitors migrate to the midline but fail to assemble into a cardiac cone and do not express markers of differentiated endocardium. Endocardial differentiation defects were rescued by myocardial but not endocardial-specific expression of hand2. In metronidazole-treated myl7:nitroreductase embryos, myocardial cells were targeted for apoptosis, which resulted in the loss of endocardial nfatc1 expression. However, endocardial cells were present and retained expression of general vascular endothelial markers. We further identified bone morphogenetic protein (BMP) as a candidate myocardium-derived signal required for endocardial differentiation. Chemical and genetic inhibition of BMP signaling at the tailbud stage resulted in severe inhibition of endocardial differentiation while there was little effect on myocardial development. Heat-shock-induced bmp2b expression rescued endocardial nfatc1 expression in hand2 mutants and in myocardium-depleted embryos. Our results indicate that the myocardium is crucial for endocardial morphogenesis and differentiation, and identify BMP as a signal involved in endocardial differentiation.

Cardiovascular and Perceptual Responses to an Ultraendurance Channel Swim: A Case Study.

Ultraendurance open water swimming presents unique physiological challenges. This case study aimed to describe cardiovascular and perceptual responses during a successful solo channel swim. Investigators followed a female swimmer's Catalina Channel (32.2 km) crossing, monitoring water temperature (T(water)) and air temperature (T(air)), distance remaining (DR), average velocity, and heart rate (HR(swim)) at regular intervals. Every 24 minutes, the swimmer reported perceived pain (on a scale of 0-10), rating of perceived exertion (RPE [scale of 6-20]), perceived thermal sensation (scale 0-8), and thirst (scale 1-9). Data are presented as mean ± SD where applicable. The participant finished in 9 hours, 2 minutes, and 48 seconds; T(water) averaged 19.1 ± 0.4ºC, and T(air) averaged 18.6 ± 0.9ºC. Her HR(swim) ranged from 148 to 155 beats/min, and thermal sensation ranged from 3 to 4. Pain inconsistently varied from 0 to 5 during the swim. The RPE remained between 12 and 14 for the first 8 hours, but increased dramatically near the end (reaching 18). Thirst sensation steadily increased throughout the swim, again reaching maximal values on completion. Physiologically and statistically significant correlations existed between thirst and DR (r = -0.905), RPE and HR(swim) (r = 0.741), RPE and DR (r = -0.694), and pain and DR (r = -0.671). The primary findings were that, despite fluctuations in perceptual stressors, the swimmer maintained a consistent exercise intensity as indicated by HR(swim); and during ultraendurance swimming, pain, RPE, and thirst positively correlated with distance swum. We hope these findings aid in the preparation and performance of future athletes by providing information on what swimmers may expect during an ultraendurance attempt and by increasing the understanding of physiological and perceptual responses during open water swimming.

Effects of coordinated compression and pinna compensation features on horizontal localization performance in hearing aid users.

BACKGROUND: Hearing-impaired listeners localize sounds better unaided than aided. Wide dynamic range compression circuits operating independently at each ear in bilateral fittings, and microphone positions of different hearing aid styles, have been cited as a reason. Two hearing aid features, inter-ear coordinated compression (IE) and pinna compensation (PC), were developed to mitigate the compromised aided localization performance. PURPOSE: This study examined the effect of IE and PC on aided localization performance in the horizontal plane with hearing-impaired listeners. RESEARCH DESIGN: A single-blind, repeated-measures design was used. STUDY SAMPLE: A total of 10 experienced hearing aid users with bilaterally symmetrical sensorineural hearing loss who had previously participated in localization training were evaluated. DATA COLLECTION AND ANALYSIS: Localization performance was measured using 12 loudspeakers spaced 30° apart on the horizontal plane. Aided performance was evaluated using a behind-the-ear hearing aid at four settings: omnidirectional microphone (Omni), Omni microphone with the PC feature, Omni microphone with IE, and Omni microphone with the PC feature and IE together. In addition, unaided localization performance was measured. RESULTS: Significant improvement in the localization accuracy was measured for sounds arriving from the back when comparing the PC with the Omni conditions. The use of IE reduced the magnitude of errors for some listeners for sounds originating from ±90°. The average reduction in the errors was 7.3°. CONCLUSIONS: This study confirmed that the use of the PC feature improved localization for sounds arriving from behind the listener. The use of IE may improve localization for some listeners for sounds arriving from the sides.

Two-color fluorescent in situ hybridization using chromogenic substrates in zebrafish.

Two-color fluorescent in situ hybridization (FISH) is a widely used technique for comparing relative gene expression patterns. Current two-color FISH protocols are not ideal for detecting weakly expressed transcripts or monitoring signal strength and background levels during the course of the reaction. Here we describe an improved FISH protocol using the conventional highly sensitive chromogenic substrates nitro blue tetrazolium (NBT)/5-bromo-4-chloro-3-indolyl phosphate (BCIP) and Vector Red in zebrafish embryos. This protocol substantially improves on existing FISH techniques by combining the advantages of long reactivity of alkaline phosphatase, chromogenic monitoring of both developing reactions, and the ability to perform subsequent high-resolution fluorescent imaging. Although tested in zebrafish, a similar approach is expected to be applicable to ISH in any model organism.

Amplification for listeners with a moderately severe high-frequency hearing loss.

BACKGROUND: Some evidence exists to support the use of an extended bandwidth (EBW) for those with a relatively mild to moderate degree of hearing loss. The use of frequency lowering is suggested for those with a severe/profound degree of hearing loss. The amplification option for those with a moderately severe hearing loss in the high frequencies is less clear. This study compared three amplification options for listeners with a moderately severe hearing loss in the high frequencies. PURPOSE: The efficacy of three amplification options-limited bandwidth to 4000 Hz, EBW, and frequency transposition-were evaluated for listeners with a moderately severe, high-frequency hearing loss. RESEARCH DESIGN: The experiment used a factorial repeated-measures design. STUDY SAMPLE: A total of 13 adults with bilateral hearing loss of 50-70 dB HL at 4000 Hz served as test participants. DATA COLLECTION AND ANALYSIS: The participants rated the sound quality of birdsongs and music when aided with the amplification options. Speech perception in quiet was measured at 50 dB SPL and 68 dB SPL input levels. The participants also completed a questionnaire on the best amplification option to use in different real-life environments during a 2 wk, take-home trial. The data were analyzed with repeated-measures analysis of variance. RESULTS: The findings showed that more listeners preferred the EBW for home use but that the frequency transposition was the least preferred. In addition, the performance of the EBW was better than that of the limited bandwidth in speech recognition but similar to that of the frequency transposition. CONCLUSIONS: The results supported the fitting of an EBW as the better choice for this group of listeners.

Evaluation of a localization training program for hearing impaired listeners.

OBJECTIVE: To evaluate the effectiveness of a home-based and a laboratory-based localization training program. DESIGN: This study examined the effectiveness of a localization training program on improving the localization ability of 15 participants with a mild-to-moderately severe hearing loss. These participants had worn the study hearing aids in a previous study. The training consisted of laboratory-based training and home-based training. The participants were divided into three groups: a control group, a group that performed the laboratory training first followed by the home training, and a group that completed the home training first followed by the laboratory training. The participants were evaluated before any training (baseline), at 2 weeks, 1 month, 2 months, and 3 months after baseline testing. All training was completed by the second month. The participants only wore the study hearing aids between the second month and the third month. Localization testing and laboratory training were conducted in a sound-treated room with a 360 degree, 12 loudspeaker array. There were three stimuli each randomly presented three times from each loudspeaker (nine test items from each loudspeaker) for a total of 108 items on each test or training trial. The stimuli, including a continuous noise, a telephone ring, and a speech passage "Search for the sound from this speaker" were high-pass filtered above 2000 Hz. The test stimuli had a duration of 300 ms, whereas the training stimuli had five durations (3 s, 2 s, 1 s, 500 ms, and 300 ms) and four back attenuation (-8, -4, -2, and 0 dB re: front presentation) values. All stimuli were presented at 30 dB SL or the most comfortable listening level of the participants. Each participant completed 6 to 8, 2 hr laboratory-based training within a month. The home training required a two-loudspeaker computer system using 30 different sounds of various durations (5) by attenuation (4) combinations. The participants were required to use the home training program for 30 min per day, 5 days per week for 4 weeks. RESULTS: Localization data were evaluated using a 30 degree error criterion. There was a significant difference in localization scores for sounds that originated from the back between baseline and 3 months for the two groups that received training. The performance of the control group remained the same across the 3 month period. Generalization to other stimuli and in the unaided condition was also seen. There were no significant differences in localization performance from other directions between baseline and 3 months. These results indicated that the training program was effective in improving the localization skills of these listeners under the current test set-up. CONCLUSIONS: The current study demonstrated that hearing aid wearers can be trained on their front/back localization skills using either laboratory-based or home-based training program. The effectiveness of the training was generalized to other acoustic stimuli and the unaided conditions when the stimulus levels were fixed.

Distinct regulation of the anterior and posterior myeloperoxidase expression by Etv2 and Gata1 during primitive Granulopoiesis in zebrafish.

Neutrophilic granulocytes are the most abundant type of myeloid cells and form an essential part of the innate immune system. In vertebrates the first neutrophils are thought to originate during primitive hematopoiesis, which precedes hematopoietic stem cell formation. In zebrafish embryos, it has been suggested that primitive neutrophils may originate in two distinct sites, the anterior (ALPM) and posterior lateral plate mesoderm (PLPM). An ETS-family transcription factor Etsrp/Etv2/ER71 has been implicated in vasculogenesis and hematopoiesis in multiple vertebrates. However, its role during neutrophil development is not well understood. Here we demonstrate using zebrafish embryos that Etv2 has a specific cell-autonomous function during primitive neutropoiesis in the anterior lateral plate mesoderm (ALPM) but has little effect on erythropoiesis or the posterior lateral plate mesoderm (PLPM) expression of neutrophil marker myeloperoxidase mpo/mpx. Our results argue that ALPM-derived neutrophils originate from etv2-expressing cells which downregulate etv2 during neutropoiesis. We further show that Scl functions downstream of Etv2 in anterior neutropoiesis. Additionally, we demonstrate that mpx expression within the PLPM overlaps with gata1 expression, potentially marking the cells with a dual myelo-erythroid potential. Intriguingly, initiation of mpx expression in the PLPM is dependent on gata1 but not etv2 function. Our results demonstrate that mpx expression is controlled differently in the ALPM and PLPM regions and describe novel roles for etv2 and gata1 during primitive neutropoiesis.

Effects of a transient noise reduction algorithm on speech understanding, subjective preference, and preferred gain.

BACKGROUND: Today's compression hearing aids with noise reduction systems may not manage transient noises effectively because of the short duration of these sounds compared to the onset times of the compressors and/or noise reduction algorithms. PURPOSE: The current study was designed to evaluate the effect of a transient noise reduction (TNR) algorithm on listening comfort, speech intelligibility in quiet, and preferred wearer gain in the presence of transients. RESEARCH DESIGN: A single-blinded, repeated-measures design was used. STUDY SAMPLE: Thirteen experienced hearing aid users with bilaterally symmetrical (≤7.5 dB) sensorineural hearing loss participated in the study. RESULTS: Speech identification in quiet (no transient noise) was identical between the TNR On and the TNR Off conditions. The participants showed subjective preference for the TNR algorithm when "comfortable listening" was used as the criterion. Participants preferred less gain than the default prescription in the presence of transient noise sounds. However, the preferred gain was 2.9 dB higher when the TNR was activated than when it was deactivated. This translated to 12.1% improvement in phoneme identification over the TNR Off condition for soft speech. CONCLUSIONS: This study demonstrated that the use of the TNR algorithm would not negatively affect speech identification. The results also suggested that this algorithm may improve listening comfort in the presence of transient noise sounds and ensure consistent use of prescribed gain. Such an algorithm may ensure more consistent audibility across listening environments.