Changing the Paradigm for School Hearing Screening Globally: Evaluation of Screening Protocols From Two Randomized Trials in Rural Alaska.

OBJECTIVES: Diagnostic accuracy was evaluated for various screening tools, including mobile health (mHealth) pure-tone screening, tympanometry, distortion product otoacoustic emissions (DPOAE), and inclusion of high frequencies to determine the most accurate screening protocol for identifying children with hearing loss in rural Alaska where the prevalence of middle ear disease is high. DESIGN: Hearing screening data were collected as part of two cluster randomized trials conducted in 15 communities in rural northwest Alaska. All children enrolled in school from preschool to 12th grade were eligible. Analysis was limited to data collected 2018 to 2019 (n = 1449), when both trials were running and measurement of high frequencies were included in the protocols. Analyses included estimates of diagnostic accuracy for each screening tool, as well as exploring performance by age and grade. Multiple imputation was used to assess diagnostic accuracy in younger children, where missing data were more prevalent due to requirements for conditioned responses. The audiometric reference standard included otoscopy, tympanometry, and high frequencies to ensure detection of infection-related and noise-induced hearing loss. RESULTS: Both the mHealth pure-tone screen and DPOAE screen performed better when tympanometry was added to the protocol (increase in sensitivity of 19.9%, 95% Confidence Interval (CI): 15.9 to 24.1 for mHealth screen, 17.9%, 95% CI: 14.0 to 21.8 for high-frequency mHealth screen, and 10.4%, 95% CI: 7.5 to 13.9 for DPOAE). The addition of 6 kHz to the mHealth pure-tone screen provided an 8.7 percentage point improvement in sensitivity (95% CI: 6.5 to 11.3). Completeness of data for both the reference standard and the mHealth screening tool differed substantially by age, due to difficulty with behavioral testing in young children. By age 7, children were able to complete behavioral testing, and data indicated that high-frequency mHealth pure-tone screen with tympanometry was the superior tool for children 7 years and older. For children 3 to 6 years of age, DPOAE plus tympanometry performed the best, both for complete data and multiply imputed data, which better approximates accuracy for children with missing data. CONCLUSIONS: This study directly evaluated pure-tone, DPOAE, and tympanometry tools as part of school hearing screening in rural Alaskan children (3 to 18+ years). Results from this study indicate that tympanometry is a key component in the hearing screening protocol, particularly in environments with higher prevalence of infection-related hearing loss. DPOAE is the preferred hearing screening tool when evaluating children younger than 7 years of age (below 2nd grade in the United States) due to the frequency of missing data with behavioral testing in this age group. For children 7 years and older, the addition of high frequencies to pure-tone screening increased the accuracy of screening, likely due to improved identification of hearing loss from noise exposure. The lack of a consistent reference standard in the literature makes comparing across studies challenging. In our study with a reference standard inclusive of otoscopy, tympanometry, and high frequencies, less than ideal sensitivities were found even for the most sensitive screening protocols, suggesting more investigation is necessary to ensure screening programs are appropriately identifying noise- and infection-related hearing loss in rural, low-resource settings.

Mobile health school screening and telemedicine referral to improve access to specialty care in rural Alaska: a cluster- randomised controlled trial.

BACKGROUND: School-based programmes, including hearing screening, provide essential preventive services for rural children. However, minimal evidence on screening methodologies, loss to follow-up, and scarcity of specialists for subsequent care compound rural health disparities. We hypothesised telemedicine specialty referral would improve time to follow-up for school hearing screening compared with standard primary care referral. METHODS: In this cluster-randomised controlled trial conducted in 15 rural Alaskan communities, USA, we randomised communities to telemedicine specialty referral (intervention) or standard primary care referral (control) for school hearing screening. All children (K-12; aged 4-21 years) enrolled in Bering Straight School District were eligible. Community randomisation occurred within four strata using location and school size. Participants were masked to group allocation until screening day, and assessors were masked throughout data collection. Screening occurred annually, and children who screened positive for possible hearing loss or ear disease were monitored for 9 months from the screening date for follow-up. Primary outcome was the time to follow-up after a positive hearing screen; analysis was by intention to treat. The trial was registered with ClinicalTrials.gov, NCT03309553. FINDINGS: We recruited participants between Oct 10, 2017, and March 28, 2019. 15 communities were randomised: eight (750 children) to telemedicine referral and seven (731 children) to primary care referral. 790 (53·3%) of 1481 children screened positive in at least one study year: 391 (52∤1%) in the telemedicine referral communities and 399 (50∤4%) in the primary care referral communities. Of children referred, 268 (68·5%) in the telemedicine referral communities and 128 (32·1%) in primary care referral communities received follow-up within 9 months. Among children who received follow-up, mean time to follow-up was 41·5 days (SD 55·7) in the telemedicine referral communities and 92·0 days (75·8) in the primary care referral communities (adjusted event-time ratio 17·6 [95% CI 6·8-45·3] for all referred children). There were no adverse events. INTERPRETATION: Telemedicine specialty referral significantly improved the time to follow-up after hearing screening in Alaska. Telemedicine might apply to other preventive school-based services to improve access to specialty care for rural children. FUNDING: Patient-Centered Outcomes Research Institute.

Hearing Norton Sound: community involvement in the design of a mixed methods community randomized trial in 15 Alaska Native communities.

Community involvement is important in good research practice. We led a community-based study to improve early detection and treatment of childhood hearing loss in rural Alaska. This study evaluated a cell phone-based hearing screening process and compared a new telemedicine specialty referral pathway to the standard primary care referral pathway. The study included community involvement, engagement, and participation from the very beginning to inform how to best design the trial. We obtained insight and feedback from community members through involvement of a core stakeholder team and through community engagement and participation in focus groups and community events. Feedback received through community involvement and participation influenced the design of the trial at key decision points. Community member guidance shaped the research question, the outcomes to be measured, and the procedures for completing the project, such as participant recruitment. This study offers an example of community involvement, engagement and participation that could be mirrored in future research to maintain the interests of participating communities. Background Effective systems for early identification and treatment of childhood hearing loss are essential in rural Alaska, where data indicate a high prevalence of childhood ear infections and hearing loss. However, loss to follow-up from school hearing screening programs is pervasive. The Hearing Norton Sound study was a mixed methods community randomized controlled trial that was developed to address this gap. The study engaged community members and participants in the design of the trial, including involvement of stakeholders as collaborators. Methods Community engagement and participation in research design occurred through focus groups and through the integration of stakeholders into the study team. Representation was cross-sectoral, involving individuals from multiple levels of the school and health system, as well as community members from each of the 15 communities. Feedback obtained between April 2017 and August 2017 informed the final design of the randomized trial, which began enrollment of children in October 2017 and concluded in March 2019. Results Stakeholder involvement and community participation shaped the design of specific trial elements (research question; comparators; outcomes and measures; telemedicine protocols; and recruitment and retention). Community involvement was strengthened by the use of multiple modalities of involvement and by the positionality of lead stakeholders on the study team. Conclusions This study highlights the effectiveness of multifaceted stakeholder involvement and participation in the design of health research conducted within Alaska Native communities. It offers an example of involvement and reporting that could be mirrored in future research in order to protect and further the interests of the participating community. Trial registration ClinicalTrials.gov, NCT03309553 , First registered 10/9/2017.

Stakeholder analysis for the development of a community pharmacy service aimed at preventing cardiovascular disease.

BACKGROUND: Participatory approaches involving stakeholders across the health care system can help enhance the development, implementation and evaluation of health services. These approaches may be particularly useful in planning community pharmacy services and so overcome challenges in their implementation into practice. Conducting a stakeholder analysis is a key first step since it allows relevant stakeholders to be identified, as well as providing planners a better understanding of the complexity of the health care system. OBJECTIVES: The main aim of this study was to conduct a stakeholder analysis to identify those individuals and organizations that could be part of a leading planning group for the development of a community pharmacy service (CPS) to prevent cardiovascular disease (CVD) in Australia. METHODS: An experienced facilitator conducted a workshop with 8 key informants of the Australian health care system. Two structured activities were undertaken. The first explored current needs and gaps in cardiovascular care and the role of community pharmacists. The second was a stakeholder analysis, using both ex-ante and ad-hoc approaches. Identified stakeholders were then classified into three groups according to their relative influence on the development of the pharmacy service. The information gathered was analyzed using qualitative content analysis. RESULTS: The key informants identified 46 stakeholders, including (1) patient/consumers and their representative organizations, (2) health care providers and their professional organizations and (3) institutions and organizations that do not directly interact with patients but organize and manage the health care system, develop and implement health policies, pay for health care, influence funding for health service research or promote new health initiatives. From the 46 stakeholders, a core group of 12 stakeholders was defined. These were considered crucial to the service's development because they held positions that could drive or inhibit progress. Secondary results of the workshop included: a list of needs and gaps in cardiovascular care (n = 6), a list of roles for community pharmacists in cardiovascular prevention (n = 12) and a list of potential factors (n = 7) that can hinder the integration of community pharmacy services into practice. CONCLUSIONS: This stakeholder analysis provided a detailed picture of the wide range of stakeholders across the entire health care system that have a stake in the development of a community pharmacy service aimed at preventing CVD. Of these, a core group of key stakeholders, with complementary roles, can then be approached for further planning of the service. The results of this analysis highlight the relevance of establishing multilevel stakeholder groups for CPS planning.

Prospective observational study protocol to investigate long-term adverse effects of methylphenidate in children and adolescents with ADHD: the Attention Deficit Hyperactivity Disorder Drugs Use Chronic Effects (ADDUCE) study.

INTRODUCTION: Methylphenidate is the most frequently used medication for the treatment of attention-deficit/hyperactivity disorder (ADHD) in Europe. Following concerns about its safety, the European Commission called for research into the long-term effects of methylphenidate on children and adolescents with ADHD. The Attention Deficit Hyperactivity Disorder Drugs Use Chronic Effects (ADDUCE) research programme was designed to address this call. At the heart of this programme is a 2-year longitudinal naturalistic pharmacovigilance study being conducted in 27 European sites. METHODS AND ANALYSIS: 3 cohorts of children and adolescents (aged 6-17) living in the UK, Germany, Italy and Hungary are being recruited:Group 1 (Medicated ADHD): 800 ADHD medication-naive children and adolescents with a clinical diagnosis of ADHD about to start methylphenidate treatment for the first time.Group 2 (Unmedicated ADHD): 400 children and adolescents with a clinical diagnosis of ADHD who have never been treated with ADHD medication and have no intention of beginning medication.Group 3 (Non-ADHD): 400 children and adolescents without ADHD who are siblings of individuals in either group 1 or 2.All participants will be assessed 5 times during their 2-year follow-up period for growth and development, psychiatric, neurological and cardiovascular health. The primary outcome measure will be the height velocity SD score. ETHICS AND DISSEMINATION: Ethical approval for the study has been granted by the East of Scotland Research Ethics Service. Following this approval, patient information leaflets and consent forms were translated as necessary and submissions made by lead sites in each of the other 3 countries to their own ethics committees. Following ethical approval in each country, local ethical permissions at each site were sought and obtained as needed. The study's website (http://www.adhd-adduce.org/page/view/2/Home) provides information for researchers, participants and the general public. TRIAL REGISTRATION NUMBER: NCT01470261.

Randomised clinical study: comparison of acceptability, patient tolerance, cardiac stress and endoscopic views in transnasal and transoral endoscopy under local anaesthetic.

BACKGROUND: Transnasal endoscopy (TNE) with ultrathin endoscopes has been advocated as an attractive alternative, for diagnostic upper endoscopy. AIM: To assess tolerability, acceptability and quality of TNE, in comparison with standard upper endoscopy (SOGD, standard oesophago-gastro-duodenoscopy) under local anaesthetic. METHODS: We prospectively recruited 157 patients (83 females/74 males) mean age 57 years. The Fujinon EG530N (5.9 mm) and EG530WR (9.4 mm) endoscopes were used. The endoscopist and all patients completed detailed questionnaires regarding tolerability, acceptance and quality of endoscopy using standard visual analogue scales (VAS). Oxygen saturation (SaO2 ), heart rate (HR) and systolic blood pressure (SBP) were recorded. Quality of biopsies was evaluated. RESULTS: Analysis included 161 procedures (TNE:79, SOGD:82) with duodenal intubation achieved in all patients. VAS scores for patient comfort were significantly better in the TNE group (7.3 vs. 5.3 respectively, P < 0.001). Twenty patients with previous experience of standard endoscopy were randomised to TNE and 19 of them (95.5%) preferred the TNE. Gagging was significantly less in the TNE group (0.12 vs. 3.41 respectively, P < 0.001). Cardiovascular stress was significantly less in the TNE group irrespective of the degree of gagging or comfort. TNE biopsies were smaller, but adequate for definitive diagnosis, similarly to standard endoscopy. CONCLUSIONS: Transnasal endoscopy is superior to SOGD in terms of comfort and patient acceptance with significantly less cardiovascular stress. TNE can routinely be used as alternative to SOGD under local anaesthetic, for diagnosis and should be preferentially offered in cardiorespiratory compromised patients.

Sex-specific time trends in first admission to hospital for peripheral artery disease in Scotland 1991-2007.

BACKGROUND: This study examined trends for all first hospital admissions for peripheral artery disease (PAD) in Scotland from 1991 to 2007 using the Scottish Morbidity Record. METHODS: First admissions to hospital for PAD were defined as an admission to hospital (inpatient and day-case) with a principal diagnosis of PAD, with no previous admission to hospital (principal or secondary diagnosis) for PAD in the previous 10 years. RESULTS: From 1991 to 2007, 41,593 individuals were admitted to hospital in Scotland for the first time for PAD. Some 23,016 (55.3 per cent) were men (mean(s.d.) age 65.7(11.7) years) and 18,577 were women (aged 70.4(12.8) years). For both sexes the population rate of first admissions to hospital for PAD declined over the study interval: from 66.7 per 100,000 in 1991-1993 to 39.7 per 100,000 in 2006-2007 among men, and from 43.5 to 29.1 per 100,000 respectively among women. After adjustment, the decline was estimated to be 42 per cent in men and 27 per cent in women (rate ratio for 2007 versus 1991: 0.58 (95 per cent confidence interval 0.55 to 0.62) in men and 0.73 (0.68 to 0.78) in women). The intervention rate fell from 80.8 to 74.4 per cent in men and from 77.9 to 64.9 per cent in women. The proportion of hospital admissions as an emergency or transfer increased, from 23.9 to 40.7 per cent among men and from 30.0 to 49.5 per cent among women. CONCLUSION: First hospital admission for PAD in Scotland declined steadily and substantially between 1991 and 2007, with an increase in the proportion that was unplanned.

Fetal demise secondary to massive rhabdomyoma in the early second trimester of pregnancy.

Rhabdomyoma is the most common cardiac tumor in fetuses, often associated with tuberous sclerosis complex and usually diagnosed in the third trimester of pregnancy, with a benign course in the majority of cases. The hemodynamic impact of cardiac tumor depends on the location and size of the mass and the presence of dysrhythmia (4). Fetal cardiac rhabdomyoma accounts for less than 10% of fetal demise cases (1). This report presents a case of massive cardiac rhabdomyoma filling the entire right heart with pericardial extension, leading to hydrops and subsequent fetal death in the early second trimester of pregnancy.

Isolated left bundle branch block mimicking outflow ventricular septal defect in a fetus.

Bundle branch block (BBB) is impossible to diagnose in a fetus with conventional fetal echocardiography. Isolated left BBB is rare in the neonatal period. Asymmetric left ventricular remodeling in isolated left BBB is secondary to chronic dyschronous activation and relaxation, resulting in thinning of the interventricular septum (IVS). This report describes a case of possible ventricular septal defect diagnosed at 34 weeks of gestation due to significant dropout in the outflow portion of the IVS seen in multiple views secondary to undiagnosed isolated left BBB in a fetus, with postnatal follow-up evaluation.

SGK1 activity in Na+ absorbing airway epithelial cells monitored by assaying NDRG1-Thr346/356/366 phosphorylation.

Studies of HeLa cells and serum- and glucocorticoid-regulated kinase 1 (SGK1) knockout mice identified threonine residues in the n-myc downstream-regulated gene 1 protein (NDRG1-Thr(346/356/366)) that are phosphorylated by SGK1 but not by related kinases (Murray et al., Biochem J 385:1-12, 2005). We have, therefore, monitored the phosphorylation of NDRG1-Thr(346/356/366) in order to explore the changes in SGK1 activity associated with the induction and regulation of the glucocorticoid-dependent Na(+) conductance (G (Na)) in human airway epithelial cells. Transient expression of active (SGK1-S422D) and inactive (SGK1-K127A) SGK1 mutants confirmed that activating SGK1 stimulates NDRG1-Thr(346/356/366) phosphorylation. Although G (Na) is negligible in hormone-deprived cells, these cells displayed basal SGK1 activity that was sensitive to LY294002, an inhibitor of 3-phosphatidylinositol phosphate kinase (PI3K). Dexamethasone (0.2 muM) acutely activated SGK1 and the peak of this response (2-3 h) coincided with the induction of G (Na), and both responses were PI3K-dependent. While these data suggest that SGK1 might mediate the rise in G (Na), transient expression of the inactive SGK1-K127A mutant did not affect the hormonal induction of G (Na) but did suppress the activation of SGK1. Dexamethasone-treated cells grown on permeable supports formed confluent epithelial sheets that generated short circuit current due to electrogenic Na(+) absorption. Forskolin and insulin both stimulated this current and the response to insulin, but not forskolin, was LY294002-sensitive and associated with the activation of SGK1. While these data suggest that SGK1 is involved in the control of G (Na), its role may be minor, which could explain why sgk1 knockout has different effects upon different tissues.

Adenosine-evoked Na+ transport in human airway epithelial cells.

BACKGROUND AND PURPOSE: Absorptive epithelia express apical receptors that allow nucleotides to inhibit Na(+) transport but ATP unexpectedly stimulated this process in an absorptive cell line derived from human bronchiolar epithelium (H441 cells) whilst UTP consistently caused inhibition. We have therefore examined the pharmacological basis of this anomalous effect of ATP. EXPERIMENTAL APPROACH: H441 cells were grown on membranes and the short circuit current (I(SC)) measured in Ussing chambers. In some experiments, [Ca(2+)](i) was measured fluorimetrically using Fura -2. mRNAs for adenosine receptors were determined by the polymerase chain reaction (PCR). KEY RESULTS: Cross desensitization experiments showed that the inhibitory response to UTP was abolished by prior exposure to ATP whilst the stimulatory response to ATP persisted in UTP-pre-stimulated cells. Apical adenosine evoked an increase in I(SC) and this response resembled the stimulatory component of the response to ATP, and could be mimicked by adenosine receptor agonists. Pre-stimulation with adenosine abolished the stimulatory component of the response to ATP. mRNA encoding A(1), A(2A) and A(2B) receptor subtypes, but not the A(3) subtype, was detected in H441 cells and adenosine receptor antagonists could abolish the ATP-evoked stimulation of Na(+) absorption. CONCLUSIONS AND IMPLICATIONS: The ATP-induced stimulation of Na(+) absorption seems to be mediated via A(2A/B) receptors activated by adenosine produced from the extracellular hydrolysis of ATP. The present data thus provide the first description of adenosine-evoked Na(+) transport in airway epithelial cells and reveal a previously undocumented aspect of the control of this physiologically important ion transport process.

Expression of intermediate-conductance, Ca2+-activated K+ channel (KCNN4) in H441 human distal airway epithelial cells.

Electrophysiological studies of H441 human distal airway epithelial cells showed that thapsigargin caused a Ca(2+)-dependent increase in membrane conductance (G(Tot)) and hyperpolarization of membrane potential (V(m)). These effects reflected a rapid rise in cellular K(+) conductance (G(K)) and a slow fall in amiloride-sensitive Na(+) conductance (G(Na)). The increase in G(Tot) was antagonized by Ba(2+), a nonselective K(+) channel blocker, and abolished by clotrimazole, a KCNN4 inhibitor, but unaffected by other selective K(+) channel blockers. Moreover, 1-ethyl-2-benzimidazolinone (1-EBIO), which is known to activate KCNN4, increased G(K) with no effect on G(Na). RT-PCR-based analyses confirmed expression of mRNA encoding KCNN4 and suggested that two related K(+) channels (KCNN1 and KCNMA1) were absent. Subsequent studies showed that 1-EBIO stimulates Na(+) transport in polarized monolayers without affecting intracellular Ca(2+) concentration ([Ca(2+)](i)), suggesting that the activity of KCNN4 might influence the rate of Na(+) absorption by contributing to G(K). Transient expression of KCNN4 cloned from H441 cells conferred a Ca(2+)- and 1-EBIO-sensitive K(+) conductance on Chinese hamster ovary cells, but this channel was inactive when [Ca(2+)](i) was <0.2 microM. Subsequent studies of amiloride-treated H441 cells showed that clotrimazole had no effect on V(m) despite clear depolarizations in response to increased extracellular K(+) concentration ([K(+)](o)). These findings thus indicate that KCNN4 does not contribute to V(m) in unstimulated cells. The present data thus establish that H441 cells express KCNN4 and highlight the importance of G(K) to the control of Na(+) absorption, but, because KCNN4 is quiescent in resting cells, this channel cannot contribute to resting G(K) or influence basal Na(+) absorption.

Cystic fibrosis and airway submucosal glands.

The chronic pulmonary infections and inflammation associated with cystic fibrosis (CF) are responsible for almost all the morbidity and mortality of this disease. Our understanding of the mechanisms that underlie the very early stages of CF lung disease, that result directly from mutations in the CF gene, is relatively poor. However, the demonstration that the predominant sites of expression of the CF gene in normal lungs are the submucosal glands, together with the histological observations showing that hyperplasia of these glands and mucin occlusion of the gland ducts are the earliest signs of disease in the CF lung, suggest that malfunction of the submucosal glands may be an important factor contributing to the early pathophysiology of CF lung disease. This review describes the function of submucosal glands in normal lungs, and the way in which their function may be disrupted in CF and may thus contribute to the early stages of CF lung disease.

Dynamics of urinary levels of hCG during early pregnancy and accuracy of the home pregnancy test.

The paper 'Dynamics of urinary levels of hCG during early pregnancy and accuracy of the home pregnancy test' has been retracted at the request of the authors. Since initiating the work 3 years ago improvements have been made to home pregnancy tests, and the device used in the study is no longer commercially available. The authors are conducting a similar study with a new pregnancy test device which suggests that some of the conclusions drawn in the retracted paper could now be misleading to health professionals and consumers.

A regulated apical Na(+) conductance in dexamethasone-treated H441 airway epithelial cells.

Treating H441 cells with dexamethasone raised the abundance of mRNA encoding the epithelial Na(+) channel alpha- and beta-subunits and increased transepithelial ion transport (measured as short-circuit current, I(sc)) from <4 microA.cm(-2) to 10-20 microA.cm(-2). This dexamethasone-stimulated ion transport was blocked by amiloride analogs with a rank order of potency of benzamil >or= amiloride > EIPA and can thus be attributed to active Na(+) absorption. Studies of apically permeabilized cells showed that this increased transport activity did not reflect a rise in Na(+) pump capacity, whereas studies of basolateral permeabilized cells demonstrated that dexamethasone increased apical Na(+) conductance (G(Na)) from a negligible value to 100-200 microS.cm(-2). Experiments that explored the ionic selectivity of this dexamethasone-induced conductance showed that it was equally permeable to Na(+) and Li(+) and that the permeability to these cations was approximately fourfold greater than to K(+). There was also a small permeability to N-methyl-d-glucammonium, a nominally impermeant cation. Forskolin, an agent that increases cellular cAMP content, caused an approximately 60% increase in I(sc), and measurements made after these cells had been basolaterally permeabilized demonstrated that this response was associated with a rise in G(Na). This cAMP-dependent control over G(Na) was disrupted by brefeldin A, an inhibitor of vesicular trafficking. Dexamethasone thus stimulates Na(+) transport in H441 cells by evoking expression of an amiloride-sensitive apical conductance that displays moderate ionic selectivity and is subject to acute control via a cAMP-dependent pathway.

Secretion of acid and base equivalents by intact distal airways.

Secretion of HCO(3)(-) by airway submucosal glands is essential for normal liquid and mucus secretion. Because the liquid bathing the airway surface (ASL) is acidic, it has been proposed that the surface epithelium may acidify HCO(3)(-)-rich glandular fluid. The aim of this study was to investigate the mechanisms by which intact distal bronchi, which contain both surface and glandular epithelium, modify pH of luminal fluid. Distal bronchi were isolated from pig lungs, cannulated in a bath containing HCO(3)(-)-buffered solution, and perfused continually with an aliquot of similar, lightly buffered solution (LBS) in which NaCl replaced NaHCO(3)(-) (pH 7 with NaOH). The pH of this circulating LBS initially acidified (by 0.053 +/- 0.0053 pH units) and transepithelial potential difference (PD) depolarized. The magnitude of acidification was increased when pH(LBS) was higher. This acidification was unaffected by luminal dimethylamiloride (DMA, 100 microM) but was inhibited by 100 nM bafilomycin A(1) (by 76 +/- 13%), suggesting involvement of vacuolar-H(+) ATPase. Addition of ACh (10 microM) evoked alkalinization of luminal LBS and hyperpolarization of transepithelial PD. The alkalinization was inhibited in HCO(3)(-)-free solutions containing acetazolamide (1 mM) and by DMA and was enhanced by bumetanide (100 microM), an inhibitor of Cl(-) secretion. The hyperpolarization was unaffected by these maneuvers. The anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoate (300 microM) and combined treatment with DMA and bumetanide blocked both the alkalinization and hyperpolarization responses to ACh. These results are consistent with earlier studies showing that ACh evokes glandular secretion of HCO(3)(-) and Cl(-). Isolated distal airways thus secrete both acid and base equivalents.

Hormonal modulation of Na(+) transport in rat fetal distal lung epithelial cells.

Isolated rat fetal distal lung epithelial (FDLE) cells were cultured (approximately 48 h) on permeable supports in medium devoid of hormones and growth factors whilst P(O2) was maintained at the level found in either the fetal (23 mmHg) or the postnatal (100 mmHg) alveolar regions. The cells became incorporated into epithelial layers that generated a basal short-circuit current (I(SC)) attributable to spontaneous Na(+) absorption. Cells at neonatal P(O2) generated larger currents than did cells at fetal P(O2), indicating that this Na(+) transport process is oxygen sensitive. Irrespective of P(O2), isoprenaline failed to elicit a discernible change in I(SC), demonstrating that beta-adrenoceptor agonists do not stimulate Na(+) transport under these conditions. However, isoprenaline did elicit cAMP accumulation in these cells, indicating that functionally coupled beta-adrenoceptors are present. Further experiments showed that isoprenaline did increase I(SC) in cells treated (24 h) with a combination of tri-iodothyronine (T(3), 10 nM) and dexamethasone (200 nM). Studies of basolaterally permeabilised cells showed that these hormones are essential for the isoprenaline-evoked increase in the apical membrane's Na(+) conductance (G(Na)), whereas isoprenaline-evoked changes in apical Cl(-) conductance (G(Cl)) can occur in both control and hormone-treated cells. Irrespective of their hormonal status, FDLE cells thus express beta-adrenoceptors that are functionally coupled to adenylate cyclase, and allow beta-adrenoceptor agonists to modulate the apical membrane's anion conductance. However, T(3) and dexamethasone are needed if these receptors are to exert control over G(Na). These hormones may thus play an important role in the functional maturation of the lung by allowing beta-adrenoceptor-mediated control over epithelial Na(+) channels in the apical plasma membrane.

Regulation of intracellular pH in Calu-3 human airway cells.

The Calu-3 human cell line exhibits features of submucosal gland serous cells and secretes HCO(3)(-). The aim of this study was to identify the HCO(3)(-) transporters present in these cells by studying their role in the regulation of intracellular pH (pH(i)). Calu-3 cells were grown on coverslips, loaded with the pH-sensitive fluorescent dye BCECF, and their fluorescence intensity monitored as an indication of pH(i). Cells were acidified with NH(4)Cl (25 mM, 1 min) and pH(i) recovery recorded. In the absence of HCO(3)(-), initial recovery was 0.208 +/- 0.016 pH units min(-1) (n = 37). This was almost abolished by removal of extracellular Na(+) and by amiloride (1 mM), consistent with the activity of a Na(+)-H(+) exchanger (NHE). In the presence of HCO(3)(-) and CO(2), recovery (0.156 +/- 0.018 pH units min(-1)) was abolished (reduced by 91.8 +/- 6.7 %, n = 7) by removal of Na(+) but only attenuated (by 63.3 +/- 5.8 %, n = 9) by amiloride. 4,4-Dinitrostilbene-2,2-disulfonic acid (DNDS) inhibited recovery by 45.8 +/- 5.0 % (n = 7). The amiloride-insensitive recovery was insensitive to changes in membrane potential, as confirmed by direct microelectrode measurements, brought about by changing extracellular [K(+)] in the presence of either valinomycin or the K(+) channel opener 1-EBIO. In addition, forskolin (10 microM), which activates the cystic fibrosis transmembrane conductance regulator Cl(-) conductance in these cells and depolarises the cell membrane, had no effect on recovery. Removal of extracellular Cl(-) trebled pH(i) recovery rates, suggesting that an electroneutral, DNDS-sensitive, Cl(-)-HCO(3)(-) exchanger together with a NHE may be involved in pH(i) regulation and HCO(3)(-) secretion in these cells. RT-PCR detected the expression of the electrogenic Na(+)-HCO(3)(-) cotransporter NBC1 and the Cl(-)-HCO(3)(-) exchanger (AE2) but not the electroneutral Na(+)-HCO(3)(-) cotransporter NBCn1.

Characterization of a novel human opsin gene with wide tissue expression and identification of embedded and flanking genes on chromosome 1q43.

As part of an ongoing search to identify novel mammalian photopigments that may mediate nonvisual tasks such as circadian entrainment and acute suppression of pineal melatonin levels, a number of recently cloned nonvisual opsin sequences were used to search dbEST. panopsin (OPN3) was one of the clones identified using this approach. Expression analysis detects two transcripts of approximately 2.1 and 2.5 kb, in a wide range of tissues including brain, liver, and retina, which encode a predicted protein of 403 amino acids. The gene was localized to the region of chromosome 1q43 also encompassing the kynurenine monooxygenase (KMO) and choroideremia-like Rab escort protein 2 (CHML) genes. KMO and panopsin overlap at their 3' ends but are transcribed in opposite directions. CHML, an intronless gene, lies in intron 1 of panopsin.

Changes in respiratory function during a wilderness multisport endurance competition.

OBJECTIVE: To document the changes in respiratory function seen in competitors during a typical wilderness multisport endurance event. METHODS: A prospective observational cohort study measuring forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) at baseline, midrace, and end of race in competitors in a 105-km ski/run/cycle/paddle race held midwinter in the mountains of Victoria, Australia. RESULTS: Twenty-five adult subjects (22 men) between 20 and 42 years of age were studied. The mean decline in FEV1 was 15.1% (95% CI 10.3-19.8) and for FVC was 13.0% (95% CI 8.1-17.9). Fourteen (56%) of the 25 subjects had a >10% decline in FEV1 and FVC, and 7 (28%) of the 25 subjects had a >20% decline. In 9 control subjects, aged between 21 and 55 years, there was no significant change in FEV1 or FVC from prerace to end of race. CONCLUSIONS: Significant declines in FEV1 and FVC are common during wilderness multisport endurance events. The focus of future research should be the etiology, which as yet remains speculative.