Methylphenidate and Sleep Difficulties in Children and Adolescents With ADHD: Results From the 2-Year Naturalistic Pharmacovigilance ADDUCE Study

OBJECTIVE

Short-term RCTs have demonstrated that MPH-treatment significantly reduces ADHD-symptoms, but is also associated with adverse events, including sleep problems. However, data on long-term effects of MPH on sleep remain limited.

METHODS

We performed a 2-year naturalistic prospective pharmacovigilance multicentre study. Participants were recruited into three groups: ADHD patients intending to start MPH-treatment (MPH-group), those not intending to use ADHD-medication (no-MPH-group), and a non-ADHD control-group. Sleep problems were assessed with the Children's-Sleep-Habits-Questionnaire (CSHQ).

RESULTS

1,410 participants were enrolled. Baseline mean CSHQ-total-sleep-scores could be considered clinically significant for the MPH-group and the no-MPH-group, but not for controls. The only group to show a significant increase in any aspect of sleep from baseline to 24-months was the control-group. Comparing the MPH- to the no-MPH-group no differences in total-sleep-score changes were found.

CONCLUSION

Our findings support that sleep-problems are common in ADHD, but don't suggest significant negative long-term effects of MPH on sleep.

SFX-01 in hospitalised patients with community-acquired pneumonia during the COVID-19 pandemic: a double-blind, randomised, placebo-controlled trial

Introduction

Sulforaphane can induce the transcription factor, Nrf2, promoting antioxidant and anti-inflammatory responses. In this study, hospitalised patients with community-acquired pneumonia (CAP) were treated with stabilised synthetic sulforaphane (SFX-01) to evaluate impact on clinical status and inflammation.

Methods

Double-blind, randomised, placebo-controlled trial of SFX-01 (300 mg oral capsule, once daily for 14 days) conducted in Dundee, UK, between November 2020 and May 2021. Patients had radiologically confirmed CAP and CURB-65 (confusion, urea >7 mmol·L-1, respiratory rate ≥30 breaths·min-1, blood pressure <90 mmHg (systolic) or ≤60 mmHg (diastolic), age ≥65 years) score ≥1. The primary outcome was the seven-point World Health Organization clinical status scale at day 15. Secondary outcomes included time to clinical improvement, length of stay and mortality. Effects on Nrf2 activity and inflammation were evaluated on days 1, 8 and 15 by measurement of 45 serum cytokines and mRNA sequencing of peripheral blood leukocytes.

Results

The trial was terminated prematurely due to futility with 133 patients enrolled. 65 patients were randomised to SFX-01 treatment and 68 patients to placebo. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was the cause of CAP in 103 (77%) cases. SFX-01 treatment did not improve clinical status at day 15 (adjusted OR 0.87, 95% CI 0.41-1.83; p=0.71), time to clinical improvement (adjusted hazard ratio (aHR) 1.02, 95% CI 0.70-1.49), length of stay (aHR 0.84, 95% CI 0.56-1.26) or 28-day mortality (aHR 1.45, 95% CI 0.67-3.16). The expression of Nrf2 targets and pro-inflammatory genes, including interleukin (IL)-6, IL-1β and tumour necrosis factor-α, was not significantly changed by SFX-01 treatment. At days 8 and 15, respectively, 310 and 42 significant differentially expressed genes were identified between groups (false discovery rate adjusted p<0.05, log2FC >1).

Conclusion

SFX-01 treatment did not improve clinical status or modulate key Nrf2 targets in patients with CAP primarily due to SARS-CoV-2 infection.

The Impact of Methylphenidate on Pubertal Maturation and Bone Age in ADHD Children and Adolescents: Results from the ADHD Drugs Use Chronic Effects (ADDUCE) Project

OBJECTIVE

The short-term safety of methylphenidate (MPH) has been widely demonstrated; however the long-term safety is less clear. The aim of this study was to investigate the safety of MPH in relation to pubertal maturation and to explore the monitoring of bone age.

METHOD

Participants from ADDUCE, a two-year observational longitudinal study with three parallel cohorts (MPH group, no-MPH group, and a non-ADHD control group), were compared with respect to Tanner staging. An Italian subsample of medicated-ADHD was further assessed by the monitoring of bone age.

RESULTS

The medicated and unmedicated ADHD groups did not differ in Tanner stages indicating no higher risk of sexual maturational delay in the MPH-treated patients. The medicated subsample monitored for bone age showed a slight acceleration of the bone maturation after 24 months, however their predicted adult height remained stable.

CONCLUSION

Our results do not suggest safety concerns on long-term treatment with MPH in relation to pubertal maturation and growth.

Environmental risk factors for respiratory infection and wheeze in young children: A multicentre birth cohort study

INTRODUCTION

Respiratory infections and wheeze have a considerable impact on the health of young children and consume significant healthcare resources. We aimed to evaluate the effect of environmental factors on respiratory infections and symptoms in early childhood.

METHODS

Environmental risk factors including: daycare attendance; breastfeeding; siblings; damp within the home; environmental tobacco smoke (ETS); child's bedroom flooring; animal exposure; road traffic density around child's home; and solid fuel pollution within home were assessed in children recruited to the GO-CHILD multicentre prospective birth cohort study. Follow-up information on respiratory infections (bronchiolitis, pneumonia, otitis media and cold or flu), wheeze and cough symptoms, healthcare utilisation and medication prescription was collected by postal questionnaires at 12 and 24 months. Log binomial and ordered logistic regression models were fitted to the data.

RESULTS

Follow-up was obtained on 1344 children. Daycare was associated with increased odds of pneumonia (odds ratio [OR] = 2.39, 95% confidence interval [CI]: 1.04-5.49), bronchiolitis (OR = 1.40, 1.02-1.90), otitis media (OR = 1.68, 1.32-2.14) and emergency department attendance for wheeze (RR = 1.81, 1.17-2.80). Breastfeeding beyond 6 months was associated with a reduced odds of bronchiolitis (OR = 0.55, 0.39-0.77) and otitis media (OR = 0.75, 0.59-0.99). Siblings at home was associated with an increased odds of bronchiolitis (OR = 1.65, 1.18-2.32) and risk of reliever inhaler prescription (RR = 1.37, 1.02-1.85). Visible damp was associated with an increased odds of wheeze (OR = 1.85, 1.11-3.19), and risk of reliever inhaler (RR = 1.73, 1.04-2.89) and inhaled corticosteroid prescription (RR = 2.61, 1.03-6.59). ETS exposure was associated with an increased odds of primary care attendance for cough or wheeze (OR = 1.52, 1.11-2.08). Dense traffic around the child's home was associated with an increased odds of bronchiolitis (OR = 1.32, 1.08-2.29).

CONCLUSION

Environmental factors likely influence the wide variation in infection frequency and symptoms observed in early childhood. Larger population studies are necessary to further inform and guide public health policy to decrease the burden of respiratory infections and wheeze in young children.

Long-term safety of methylphenidate in children and adolescents with ADHD: 2-year outcomes of the Attention Deficit Hyperactivity Disorder Drugs Use Chronic Effects (ADDUCE) study

BACKGROUND

Methylphenidate is the most frequently prescribed medication for the treatment of ADHD in children and adolescents in many countries. Although many randomised controlled trials support short-term efficacy, tolerability, and safety, data on long-term safety and tolerability are scarce. The aim of this study was to investigate the safety of methylphenidate over a 2-year period in relation to growth and development, psychiatric health, neurological health, and cardiovascular function in children and adolescents.

METHODS

We conducted a naturalistic, longitudinal, controlled study as part of the ADDUCE research programme in 27 European child and adolescent mental health centres in the UK, Germany, Switzerland, Italy, and Hungary. Participants aged 6-17 years were recruited into three cohorts: medication-naive ADHD patients who intended to start methylphenidate treatment (methylphenidate group), medication-naive ADHD patients who did not intend to start any ADHD medication (no-methylphenidate group), and a control group without ADHD. Children with ADHD diagnosed by a qualified clinician according to the DSM-IV criteria and, in the control group, children who scored less than 1·5 on average on the Swanson, Nolan, and Pelham IV rating scale for ADHD items, and whose hyperactivity score on the parent-rated Strengths and Difficulties Questionnaire was within the normal range (<6) were eligible for inclusion. Participants were excluded if they had previously taken any ADHD medications but remained eligible if they had previously taken or were currently taking other psychotropic drugs. The primary outcome was height velocity (height velocity SD score; estimated from at least two consecutive height measurements, and normalised with reference to the mean and SD of a population of the same age and sex).

FINDINGS

Between Feb 01, 2012, and Jan 31, 2016, 1410 participants were enrolled (756 in methylphenidate group, 391 in no-methylphenidate group, and 263 in control group). 1070 (76·3%) participants were male, 332 (23·7%) were female, and for eight gender was unknown. The average age for the cohort was 9·28 years (SD 2·78; IQR 7-11). 1312 (93·0%) of 1410 participants were White. The methylphenidate and no-methylphenidate groups differed in ADHD symptom severity and other characteristics. After controlling for the effects of these variables using propensity scores, there was little evidence of an effect on growth (24 months height velocity SD score difference -0·07 (95% CI -0·18 to 0·04; p=0·20) or increased risk of psychiatric or neurological adverse events in the methylphenidate group compared with the no-methylphenidate group. Pulse rate and systolic and diastolic blood pressure were higher in the methylphenidate group compared with the no-methylphenidate group after 24 months of treatment. No serious adverse events were reported during the study.

INTERPRETATION

Our results suggest that long-term treatment with methylphenidate for 2 years is safe. There was no evidence to support the hypothesis that methylphenidate treatment leads to reductions in growth. Methylphenidate-related pulse and blood pressure changes, although relatively small, require regular monitoring.

FUNDING

EU Seventh Framework Programme.

Laying the foundations for hepatitis C elimination: evaluating the development and contribution of community care pathways to diagnostic efforts

BACKGROUND

Hepatitis C Virus (HCV) is a public health threat which contributes substantially to the global burden of liver disease. There is much debate about effective approaches to scaling up diagnosis of HCV among risk groups. Tayside, a region in the East of Scotland, developed low-threshold community pathways for HCV to lay the foundations of an elimination strategy. In this retrospective study, we sought to: quantify the contribution of community pathways to increasing HCV diagnosis; understand if shifting diagnosis to community settings led to a higher proportion of individuals tested for HCV being actively infected; and describe functional characteristics of the care pathways.

METHODS

Descriptive statistics were used to for analysis of routinely-collected HCV testing data from 1999 to 2017, and a review of the development of the care pathways was undertaken. Community-based testing was offered through general practices (GP); nurse outreach clinics; prisons; drug treatment services; needle and syringe provision (NSP) sites; community pharmacies; and mosques.

RESULTS

Anti-HCV screening was undertaken on 109,430 samples, of which 5176 (4.7%) were reactive. Of all samples, 77,885 (71.2%) were taken in secondary care; 25,044 (22.9%) in GPs; 2970 (2.7%) in prisons; 2415 (2.2%) in drug services; 753 (0.7%) in NSPs; 193 (0.2%) pharmacies; and 170 (0.1%) in mosques. The highest prevalence of HCV infection among those tested was in NSP sites (26%), prisons (14%), and drug treatment centres (12%).

CONCLUSIONS

Decentralised care pathways, particularly in harm reduction and other drug service settings, were key to increasing diagnosis of HCV in the region, but primary and secondary care remain central to elimination efforts.

Mannose-binding lectin genotype is associated with respiratory disease in young children: A multicenter cohort study

BACKGROUND

Mannose-binding lectin (MBL) is an important component of the innate immune system. Polymorphisms in the MBL2 gene and promoter region are directly associated with MBL-deficiency. We sought to determine the association between MBL genotype on the frequency of common childhood respiratory infections, respiratory symptoms, and atopic outcomes in early childhood.

METHODS

MBL2 gene variants were analyzed in newborns recruited to the GO-CHILD multicenter prospective cohort study. Follow-up for respiratory infection and atopy diagnoses and symptoms, healthcare utilization, and medication prescription were conducted by postal questionnaires at 12 and 24 months.

RESULTS

Genotyping and follow-up were completed in 1004 children. Genotypes associated with MBL-deficiency were associated with an increased risk of bronchiolitis (relative risk [RR] 1.95, 95% confidence interval [CI] 1.33-2.85) and pneumonia (RR 2.46, 95% CI 1.16-5.22). MBL-deficient genotypes were associated with an increased risk of wheeze with shortness of breath episodes (RR 1.22, 95% CI 1.04-1.43), emergency department attendance (RR 1.90 95% CI 1.13-3.19), and hospital admission (RR 2.01, 95% CI 1.04-3.89) for wheeze. MBL-deficient genotypes were associated with a reduced risk of developing atopic dermatitis (RR 0.72, 95% CI 0.53-0.98).

CONCLUSION

The positive association between MBL-deficient genotypes and bronchiolitis and pneumonia, as well as a severe wheeze phenotype in some young children, supports the hypothesis that MBL is an important component of innate immunity in the vulnerable period before the maturation of the adaptive immune system. Identification of disease-modifying genotypes may help target preventative strategies in high-risk infants.

Reaching people receiving opioid agonist therapy at community pharmacies with hepatitis C virus: an international randomised controlled trial

BACKGROUND

Conventional healthcare models struggle to engage those at risk of hepatitis C virus (HCV) infection. This international study evaluated point-of-care (PoC) HCV RNA diagnostic outreach and direct-acting antiviral (DAA) treatment for individuals receiving opioid agonist therapy (OAT) in community pharmacies.

AIMS

We assessed the effectiveness of a roving nurse-led pathway offering PoC HCV RNA testing to OAT clients in community pharmacies relative to conventional care.

METHODS

Pharmacies in Scotland, Wales, and Australia were randomised to provide PoC HCV RNA testing or conventional referral. Pharmacists directed OAT clients to on-site nurses (intervention) or local clinics (control). Infected participants were treated with DAAs, alongside OAT. Primary outcome was the number of participants with sustained virologic response at 12 weeks (SVR) and analysed using mixed effects logistic regression in the intention-to-treat (ITT) population.

RESULTS

Forty pharmacies were randomised. The ITT population contained 1410 OAT clients. In the conventional arm (n = 648), 62 (10%) agreed to testing, 17 (27%) were tested, 6 (35%) were positive and 5 (83%) initiated treatment. In the intervention arm (n = 762), 148 (19%) agreed to testing, 144 (97%) were tested, 23 (16%) were positive and 22 (96%) initiated treatment. SVR was obtained by 2 (40%; conventional) and 18 (82%; intervention). Intervention arm participants had higher odds of testing, OR 16.95 (7.07-40.64, p < 0.001); treatment, OR 4.29 (1.43-12.92, p = 0.010); and SVR, OR 8.64 (1.82-40.91, p = 0.007).

CONCLUSIONS

Nurse-led PoC diagnosis in pharmacies made HCV care more accessible for OAT clients relative to conventional care. However, strategies to improve testing uptake are required.

TRIAL REGISTRATION

NCT03935906.

Real-world outcomes of rapid regional hepatitis C virus treatment scale-up among people who inject drugs in Tayside, Scotland

BACKGROUND

In 2017, Tayside, a region in the East of Scotland, rapidly scaled-up Hepatitis C Virus (HCV) outreach and treatment among People Who Inject Drugs (PWID) using novel community care pathways.

AIMS

We aimed to determine treatment outcomes for PWID during the scale-up against pre-determined targets; and assess re-infection, mortality, and post-treatment follow up.

METHODS

HCV treatment was delivered in community pharmacies, drug treatment centres, nurse-led outreach clinics, prisons, and needle exchanges, alongside conventional hospital care. We retrospectively analysed clinical outcomes and compared pathways using logistic regression models.

RESULTS

Of 800 estimated HCV-infected PWID, 718 (90%) were diagnosed. 713 treatments commenced among 662 (92%) PWID, delivering 577 (81%) Sustained Virologic Responses (SVR). SVR was 91% among those who attended for testing. Forty-six individuals were treated more than once. Needle exchanges and community pharmacies initiated 49% of all treatments. Regression analyses implied pharmacies had superior follow-up, but there was no difference in likelihood of achieving SVR in community pathways relative to hospital care. Re-infection occurred 39 times over 256.57 person years (PY), yielding a rate of 15.20 per 100 PY (95% CI 10.81-20.78). 54 deaths occurred (29 drug related) over 1,553.04 PY, yielding a mortality rate of 3.48 per 100 PY (95% CI 2.61-4.54). Drug-related mortality was 1.87 per 100 PY (95% CI 1.25-2.68).

CONCLUSIONS

Rapid HCV treatment scale-up to PWID in community settings, whilst maintaining high SVR, is achievable. However, other interventions are required to minimise re-infection; reduce drug-related deaths; and improve post-SVR follow-up testing regionally.

Clinical effectiveness of pharmacist-led versus conventionally delivered antiviral treatment for hepatitis C virus in patients receiving opioid substitution therapy: a pragmatic, cluster-randomised trial

BACKGROUND

Highly effective direct-acting antiviral drugs provide the opportunity to eliminate hepatitis C virus (HCV) infection, but established pathways can be ineffective. We aimed to examine whether a community pharmacy care pathway increased treatment uptake, treatment completion, and cure rates for people receiving opioid substitution therapy, compared with conventional care.

METHODS

This cluster-randomised trial was done in Scottish community pharmacies. Before participants were recruited, pharmacies were randomly assigned (1:1) to refer patients with evidence of HCV antibodies to conventional care or offered them care in the pharmacy (pharmacist-led care). Pharmacies were stratified by location. All pharmacies were trained to offer dried blood spot testing. All eligible participants had received opioid substitution therapy for approximately 3 months, and those eligible to receive treatment in the pharmacist-led care pathway were HCV PCR positive, were infected with HCV genotype 1 or 3, and were willing to have a pharmacist supervise their antiviral drug administration. Neither pharmacists nor patients were masked to treatment allocation. In both groups, assessment blood samples were taken, infection with HCV was confirmed, and daily oral ledipasvir-sofosbuvir (90 mg ledipasivir plus 400 mg sofosbuvir) for 8 weeks for genotype 1 or daily oral sofosbuvir (400 mg) plus oral daclatasvir (60 mg) for 12 weeks for genotype 3 was prescribed by a nurse (conventional care group) or pharmacist (pharmacist-led care group). In the conventional care group, the patient received care at a treatment centre. Once prescribed, medication in both groups was delivered as daily modified directly observed therapy alongside opioid substitution therapy in the participants' pharmacy where treatment was observed on 6 days per week. The primary outcome was the number of patients with sustained virological response 12 weeks after completion of treatment (SVR12) as a proportion of the number of people receiving opioid substitution therapy at participating pharmacies. Participants were monitored at each visit for nausea and fatigue; other adverse events were recorded as free text. Secondary outcomes compared key points on treatment pathway between the two groups. These key points were the proportion of patients having dry blood spot testing, the proportion of patients initiating HCV treatment, the proportion of patients completing the 8 or 12 week HCV course of treatment, and the proportion of patients with sustained virological response at 12 months. This study is registered with ClinicalTrials.gov, NCT02706223.

FINDINGS

56 pharmacies were randomly assigned (28 to each group; one pharmacy withdrew from the conventional care group). The 55 participating pharmacies included 2718 patients receiving opioid substitution therapy (1365 in the pharmacist-led care group and 1353 in the conventional care group). More patients met the primary endpoint of SVR12 in the pharmacist-led care group (98 [7%] of 1365) than in the conventional care group (43 [3%] of 1353; odds ratio 2·375, 95% CI 1·555-3·628, p<0·0001). More users of opioid substitution therapy in the pharmacist-led care group versus the conventional care group agreed to dry blood spot testing (245 [18%] of 1365 vs 145 [11%] of 1353, 2·292, 0·968-5·427, p=0·059); initiated treatment (112 [8%] of 1365 vs 61 [4%] of 1353, 1·889, 1·276-2·789, p=0·0015) and completed treatment (108 [8%] of 1365 vs 58 [4%] of 1353, 1·928, 1·321-2·813, p=0·0007). The data for sustained virological response at 12 months are not reported in this study: patients remain in follow-up for this outcome. No serious adverse events were recorded.

INTERPRETATION

Using pharmacists to deliver an HCV care pathway made testing and treatment more accessible for patients, improved engagement, and maintained high treatment success rates. The use of this pathway could be a key part of an integrated and effective approach to HCV elimination at a community level.

FUNDING

Partnership between the Scottish Government, Gilead Sciences, and Bristol-Myers Squib.

Neurological and psychiatric adverse effects of long-term methylphenidate treatment in ADHD: A map of the current evidence

Methylphenidate (MPH), the most common medication for children with Attention Deficit/Hyperactivity Disorder (ADHD) in many countries, is often prescribed for long periods of time. Any long-term psychotropic treatment in childhood raises concerns about possible adverse neurological and psychiatric outcomes. We aimed to map current evidence regarding neurological and psychiatric outcomes, adverse or beneficial, of long-term MPH (> 1 year) treatment in ADHD. We coded studies using a "traffic light" system: Green: safe/favours MPH; Amber: warrants caution; Red: not safe/not well-tolerated. Un-categorisable study findings were coded as "Unclear". Although some evidence suggests an elevated risk of psychosis and tics, case reports describe remission on discontinuation. Several studies suggest that long-term MPH may reduce depression and suicide in ADHD. Evidence suggests caution in specific groups including pre-school children, those with tics, and adolescents at risk for substance misuse. We identified a need for more studies that make use of large longitudinal databases, focus on specific neuropsychiatric outcomes, and compare outcomes from long-term MPH treatment with outcomes following shorter or no pharmacological intervention.

Randomised controlled trial conducted in injecting equipment provision sites to compare the effectiveness of different hepatitis C treatment regimens in people who inject drugs: A Direct obserVed therApy versus fortNightly CollEction study for HCV treatment-ADVANCE HCV protocol study

INTRODUCTION

Hepatitis C is a blood-borne virus (HCV) that can seriously damage the liver and is spread mainly through blood-to-blood contact with an infected person. Over 85% of individuals who have HCV in Scotland became infected following injecting drug use. Since people who inject drugs (PWID) are the main source of new infections, theoretical modelling has suggested that treatment of HCV infection in PWID may effectively reduce HCV prevalence and accomplish elimination. This protocol describes a clinical trial delivering HCV treatment within injecting equipment provision sites (IEPS) in Tayside, Scotland.

METHODS AND ANALYSIS

PWID attending IEPS are tested for HCV and, if they are chronically infected with HCV and eligible, invited to receive treatment within the IEPS. They are randomised to one of three treatment regimens; daily observed treatment, treatment dispensed every 2 weeks and treatment dispensed every 2 weeks together with an adherence psychological intervention (administered before treatment begins). The primary outcome is comparison of the rate of successful treatment (SVR₁₂) in each treatment group. Secondary analyses include assessment of adherence, reinfection rates, viral resistance to treatment and interaction of the treatment with illicit drugs.

ETHICS AND DISSEMINATION

The ADVANCE (A Direct obserVed therApy versus fortNightly CollEction) HCV trial was given favourable opinion by East of Scotland Research Ethics Committee (LR/17/ES/0089) prior to commencement.

TRIAL REGISTRATION NUMBERS

European Clinical Trials Database (EudraCT) (2017-001039-38) and ClinicalTrials.gov (NCT03236506).

Clinical effectiveness of pharmacy-led versus conventionally delivered antiviral treatment for hepatitis C in patients receiving opioid substitution therapy: a study protocol for a pragmatic cluster randomised trial

INTRODUCTION

Hepatitis C virus (HCV) infection affects 0.7% of the general population, and up to 40% of people prescribed opioid substitution therapy (OST) in Scotland. In conventional care, less than 10% of OST users are tested for HCV and less than 25% of these initiate treatment. Community pharmacists see this group frequently to provide OST supervision. This study examines whether a pharmacist-led 'test & treat' pathway increases cure rates for HCV.

METHODS AND ANALYSIS

This protocol describes a cluster-randomised trial where 60 community pharmacies provide either conventional or pharmacy-led care. All pharmacies offer dried blood spot testing (DBST) for HCV. Participants have attended the pharmacy for OST for 3 months; are positive for HCV genotype 1 or 3; are not co-infected with HIV and/or hepatitis B; have no decompensated liver disease; are not pregnant. For conventional care, pharmacists refer HCV-positive participants to a local centre for assessment. In the pharmacy-led arm, pharmacists assess participants themselves in the pharmacy. Drug prescribing is by nurse prescribers (conventional arm) or pharmacist prescribers (pharmacy-led arm). Treatment in both arms is delivered as daily modified directly observed therapy in a pharmacy. Primary trial outcome is number of sustained virological responses at 12 weeks after treatment completion. Secondary trial outcomes are number of tests taken; treatment uptake; completion; adherence; re-infection. An economic evaluation will assess potential cost-effectiveness. Qualitative research interviews with clients and health professionals assess acceptability of a pharmacist-led pathway.

ETHICS AND DISSEMINATION

This protocol has been ethically approved by the East of Scotland Research Ethics Committee 2 (15/ES/0086) and complies with the Declaration of Helsinki and principles of Good Clinical Practice. Caldicott guardian approval was given on 16 December 2016 to allow NHS Tayside to pass information to the cluster community pharmacies about the HCV test status of patients that they are seeing to provide OST supervision. NHS R&D approvals have been obtained from each health board taking part in the study. Informed consent is obtained before study enrolment and only anonymised data are stored in a secured database, enabling an audit trail. Results will be submitted to international peer-reviewed journals and presented at international conferences.

TRIAL REGISTRATION NUMBER

NCT02706223; Pre-results.

Association of Risk of Suicide Attempts With Methylphenidate Treatment

IMPORTANCE

Patients with attention-deficit/hyperactivity disorder (ADHD) are at an increased risk of attempting suicide. Stimulants, such as methylphenidate hydrochloride, are the most common treatment for ADHD, but the association between their therapeutic use and suicide is unclear.

OBJECTIVE

To investigate the association between methylphenidate and the risk of suicide attempts.

DESIGN, SETTING, AND PARTICIPANTS

A population-based, electronic medical records database from the Hong Kong Clinical Data Analysis & Reporting System was used to identify 25 629 individuals aged 6 to 25 years who were treated with methylphenidate between January 1, 2001, and December 31, 2015. Those who had attempted suicide were included in the analysis. A self-controlled case series design was used to control for time-invariant characteristics of the patients.

MAIN OUTCOMES AND MEASURES

Relative incidence of suicide attempt during periods when patients were exposed to methylphenidate compared with nonexposed periods.

RESULTS

Among 25 629 patients with methylphenidate prescriptions, 154 had their first recorded suicide attempt within the study period; of these individuals, 111 (72.1%) were male; mean (SD) age at baseline was 7.15 (2.19) years. The overall incidence of suicide attempts during methylphenidate treatment was 9.27 per 10 000 patient-years. An increased risk of suicide attempts was detected during the 90-day period before methylphenidate was initiated, with an incidence rate ratio (IRR) of 6.55 (95% CI, 3.37-12.72). The IRR remained elevated during the first 90 days of treatment (IRR, 3.91; 95% CI, 1.62-9.42) before returning to baseline levels during ongoing treatment (IRR, 1.35; 95% CI, 0.77-2.38). When the risk during the first 90 days of treatment was compared with the 90 days preceding first treatment, the incidence of suicide attempts was not elevated (IRR, 0.78; 95% CI, 0.26-2.35).

CONCLUSIONS AND RELEVANCE

The incidence of suicide attempts was higher in the period immediately before the start of methylphenidate treatment. The risk remained elevated immediately after the start of methylphenidate treatment and returned to baseline levels during continuation of methylphenidate treatment. The observed higher risk of suicide attempts before treatment may reflect emerging psychiatric symptoms that trigger medical consultations that result in a decision to begin ADHD treatment. Therefore, this study's results do not support a causal association between methylphenidate treatment and suicide attempts.

Personalized Medication Response Prediction for Attention-Deficit Hyperactivity Disorder: Learning in the Model Space vs. Learning in the Data Space

Attention-Deficit Hyperactive Disorder (ADHD) is one of the most common mental health disorders amongst school-aged children with an estimated prevalence of 5% in the global population (American Psychiatric Association, 2013). Stimulants, particularly methylphenidate (MPH), are the first-line option in the treatment of ADHD (Reeves and Schweitzer, 2004; Dopheide and Pliszka, 2009) and are prescribed to an increasing number of children and adolescents in the US and the UK every year (Safer et al., 1996; McCarthy et al., 2009), though recent studies suggest that this is tailing off, e.g., Holden et al. (2013). Around 70% of children demonstrate a clinically significant treatment response to stimulant medication (Spencer et al., 1996; Schachter et al., 2001; Swanson et al., 2001; Barbaresi et al., 2006). However, it is unclear which patient characteristics may moderate treatment effectiveness. As such, most existing research has focused on investigating univariate or multivariate correlations between a set of patient characteristics and the treatment outcome, with respect to dosage of one or several types of medication. The results of such studies are often contradictory and inconclusive due to a combination of small sample sizes, low-quality data, or a lack of available information on covariates. In this paper, feature extraction techniques such as latent trait analysis were applied to reduce the dimension of on a large dataset of patient characteristics, including the responses to symptom-based questionnaires, developmental health factors, demographic variables such as age and gender, and socioeconomic factors such as parental income. We introduce a Bayesian modeling approach in a "learning in the model space" framework that combines existing knowledge in the literature on factors that may potentially affect treatment response, with constraints imposed by a treatment response model. The model is personalized such that the variability among subjects is accounted for by a set of subject-specific parameters. For remission classification, this approach compares favorably with conventional methods such as support vector machines and mixed effect models on a range of performance measures. For instance, the proposed approach achieved an area under receiver operator characteristic curve of 82-84%, compared to 75-77% obtained from conventional regression or machine learning ("learning in the data space") methods.

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.

Mucous solids and liquid secretion by airways: studies with normal pig, cystic fibrosis human, and non-cystic fibrosis human bronchi

To better understand how airways produce thick airway mucus, nonvolatile solids were measured in liquid secreted by bronchi from normal pig, cystic fibrosis (CF) human, and non-CF human lungs. Bronchi were exposed to various secretagogues and anion secretion inhibitors to induce a range of liquid volume secretion rates. In all three groups, the relationship of solids concentration (percent nonvolatile solids) to liquid volume secretion rate was curvilinear, with higher solids concentration associated with lower rates of liquid volume secretion. In contrast, the secretion rates of solids mass and water mass as functions of liquid volume secretion rates exhibited positive linear correlations. The y-intercepts of the solids mass-liquid volume secretion relationships for all three groups were positive, thus accounting for the higher solids concentrations in airway liquid at low rates of secretion. Predictive models derived from the solids mass and water mass linear equations fit the experimental percent solids data for the three groups. The ratio of solids mass secretion to liquid volume secretion was 5.2 and 2.4 times higher for CF bronchi than for pig and non-CF bronchi, respectively. These results indicate that normal pig, non-CF human, and CF human bronchi produce a high-percent-solids mucus (>8%) at low rates of liquid volume secretion (≤1.0 μl·cm(-2)·h(-1)). However, CF bronchi produce mucus with twice the percent solids (~8%) of pig or non-CF human bronchi at liquid volume secretion rates ≥4.0 μl·cm(-2)·h(-1).

Effects of peroxisome proliferator-activated receptor gamma agonists on Na+ transport and activity of the kinase SGK1 in epithelial cells from lung and kidney

BACKGROUND AND PURPOSE

Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists, such as rosiglitazone and pioglitazone, sensitize cells to insulin, and are therefore used to treat type 2 diabetes. However, in some patients, these drugs induce oedema, and the present study tests the hypothesis that this side effect reflects serum and glucocorticoid-inducible kinase 1 (SGK1)-dependent enhancement of epithelia Na(+) absorption.

EXPERIMENTAL APPROACH

Na(+) absorbing epithelial cells (H441 cells, mpkCCD cells) on permeable membranes were mounted in Ussing chambers, and the effects of rosiglitazone (2 microM) and pioglitazone (10 microM) on transepithelial Na(+) absorption were quantified electrometrically. Changes in SGK1 activity were assessed by monitoring phosphorylation of residues within an endogenous protein.

KEY RESULTS

Both cell types absorbed Na(+) via an electrogenic process that was enhanced by insulin. In mpkCCD cells, this stimulation of Na(+) transport was associated with increased activity of SGK1, whereas insulin regulated Na(+) transport in H441 cells through a mechanism that did not involve activation of this kinase. Rosiglitazone and pioglitazone had no discernible effect on transepithelial Na(+) absorption in unstimulated or insulin-stimulated cells and failed to alter cellular SGK1 activity.

CONCLUSIONS AND IMPLICATIONS

Our results do not support the view that PPARgamma agonists stimulate epithelial Na(+) absorption or alter the control of cellular SGK1 activity. It is therefore likely that other mechanisms are involved in PPARgamma-mediated fluid retention, and a better understanding of these mechanisms may help with the identification of patients likely to develop oedema or heart failure when treated with these drugs.

A Ba2+-resistant, acid-sensitive K+ conductance in Na+-absorbing H441 human airway epithelial cells

By analysis of whole cell membrane currents in Na(+)-absorbing H441 human airway epithelial cells, we have identified a K(+) conductance (G(K)) resistant to Ba(2+) but sensitive to bupivacaine or extracellular acidification. In polarized H441 monolayers, we have demonstrated that bupivacaine, lidocaine, and quinidine inhibit basolateral membrane K(+) current (I(Bl)) whereas Ba(2+) has only a weak inhibitory effect. I(Bl) was also inhibited by basolateral acidification, and, although subsequent addition of bupivacaine caused a further fall in I(Bl), acidification had no effect after bupivacaine, demonstrating that cells grown under these conditions express at least two different bupivacaine-sensitive K(+) channels, only one of which is acid sensitive. Basolateral acidification also inhibited short-circuit current (I(SC)), and basolateral bupivacaine, lidocaine, quinidine, and Ba(2+) inhibited I(SC) at concentrations similar to those needed to inhibit I(Bl), suggesting that the K(+) channels underlying I(Bl) are part of the absorptive mechanism. Analyses using RT-PCR showed that mRNA encoding several two-pore domain K(+) (K2P) channels was detected in cells grown under standard conditions (TWIK-1, TREK-1, TASK-2, TWIK-2, KCNK-7, TASK-3, TREK-2, THIK-1, and TALK-2). We therefore suggest that K2P channels underlie G(K) in unstimulated cells and so maintain the driving force for Na(+) absorption. Since this ion transport process is vital to lung function, K2P channels thus play an important but previously undocumented role in pulmonary physiology.

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.

Ionic mechanism of forskolin-induced liquid secretion by porcine bronchi

cAMP-elevating agents such as forskolin and vasoactive intestinal peptide induce liquid secretion by tracheobronchial submucosal glands. This pathway is thought to be CFTR dependent and thus defective in cystic fibrosis; however, the ionic mechanism that drives this secretion process is incompletely understood. To better define this mechanism, we studied the effects of ion transport inhibitors on the forskolin-induced liquid secretion response (Jv) of porcine distal bronchi. The forskolin-induced Jv was driven by a combination of bumetanide-sensitive Cl− secretion and DIDS-sensitive HCO3− secretion. When Cl− secretion was inhibited with bumetanide, Na+/H+ exchange-dependent HCO3− secretion was apparently induced to compensate for the loss of Cl− secretion. The forskolin-induced Jv was significantly inhibited by the anion channel blockers 5-nitro-2-(3-phenylpropylamino)benzoic acid, diphenylamine-2-carboxylate, and glibenclamide. We conclude that the forskolin-induced Jv shares many characteristics of cholinergically induced secretion except for the presence of a DIDS-sensitive component. Although the identity of the DIDS-sensitive component is unclear, we speculate that it represents a basolateral membrane Na+-HCO3− cotransporter or an Na+-dependent anion exchanger, which could account for transepithelial HCO3− secretion.

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.

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.

Liquid secretion properties of airway submucosal glands

The tracheobronchial submucosal glands secrete liquid that is important for hydrating airway surfaces, supporting mucociliary transport, and serving as a fluid matrix for numerous secreted macromolecules including the gel-forming mucins. This review details the essential structural elements of airway glands and summarizes what is currently known regarding the ion transport processes responsible for producing the liquid component of gland secretion. Liquid secretion most likely arises from serous cells and is principally under neural control with muscarinic agonists, substance P, and vasoactive intestinal peptide (VIP) functioning as effective secretogogues. Liquid secretion is driven by the active transepithelial secretion of both Cl(-) and HCO(3)(-) and at least a portion of this process is mediated by the cystic fibrosis transmembrane conductance regulator (CFTR), which is highly expressed in glands. The potential role of submucosal glands in cystic fibrosis lung disease is discussed.

O2 can raise fetal pneumocyte Na+ conductance without affecting ENaC mRNA abundance

In fetal pneumocytes, increasing P(O(2)) can raise apical Na(+) conductance (G(Na(+))) and increase the abundance of epithelial Na(+) channel subunit (alpha-, beta-, and gamma-ENaC) mRNA, suggesting that the rise in G(Na(+)), which may be important to the perinatal maturation of the lung, reflects O(2)-evoked ENaC gene expression. However, we now show that physiologically relevant increases in P(O(2)) do not affect alpha-, beta-, and gamma-ENaC mRNA abundance in pneumocytes maintained (approximately 48 h) in hormone-free medium or in medium supplemented with dexamethasone and tri-iodothyronine, although the response does persist in cells maintained in medium containing a complex mixture of hormones/growth factors. However, parallel electrometric studies revealed clear increases in G(Na(+)) under all tested conditions and so it is now clear that O(2)-evoked increases in G(Na(+)) can occur without corresponding increases in ENaC mRNA abundance. It is therefore unlikely that this rise in G(Na(+)) is secondary to O(2)-evoked ENaC gene expression.

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.

Liquid secretion inhibitors reduce mucociliary transport in glandular airways

Because of its possible importance in cystic fibrosis (CF) pulmonary pathogenesis, the effect of anion and liquid secretion inhibitors on airway mucociliary transport was examined. When excised porcine tracheas were treated with ACh to induce gland liquid secretion, the rate of mucociliary transport was increased nearly threefold from 2.5 +/- 0.5 to 6.8 +/- 0.8 mm/min. Pretreatment with both bumetanide and dimethylamiloride (DMA), to respectively inhibit Cl(-) and HCO secretion, significantly reduced mucociliary transport in the presence of ACh by 92%. Pretreatment with the anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid similarly reduced mucociliary transport in ACh-treated airways by 97%. These agents did not, however, reduce ciliary beat frequency. Luminal application of benzamil to block liquid absorption significantly attenuated the inhibitory effects of bumetanide and DMA on mucociliary transport. We conclude that anion and liquid secretion is essential for normal mucociliary transport in glandular airways. Because the CF transmembrane conductance regulator protein likely mediates Cl(-), HCO, and liquid secretion in normal glands, we speculate that impairment of gland liquid secretion significantly contributes to defective mucociliary transport in CF.

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.

Differential effects of furosemide on porcine bronchial arterial and airway smooth muscle

Furosemide attenuates airway obstruction in asthmatic subjects when administered as an aerosol pretreatment. This protective effect of furosemide could be related to relaxation of bronchial smooth muscle or to increased bronchial blood flow. To determine whether furosemide dilates bronchial smooth muscle, isometric contractile responses in distal bronchi from young pigs were studied. In bronchial smooth muscle rings that were precontracted with 10(-5) M acetylcholine, significant relaxation occurred with 10(-8) to 3 x 10(-6) M isoproterenol but not with 10(-8) to 10(-3) M furosemide. In contrast, bronchial arteries that were precontracted with either 10(-4) M norepinephrine or 10(-8) M vasopressin significantly relaxed in response to 10(-4) to 3 x 10(-3) M and 10(-3) to 3 x 10(-3) M furosemide, respectively. We conclude that furosemide, under the described experimental conditions, relaxes airway vascular smooth muscle but not bronchial smooth muscle. These results are consistent with previous suggestions that inhaled furosemide increases blood flow to airway tissues (Gilbert IA, Lenner KA, Nelson JA, Wolin AD, and Fouke JM. J Appl Physiol 76: 409-415, 1994).

Differential effects of UTP and ATP on ion transport in porcine tracheal epithelium

Isolated segments of porcine tracheal epithelium were mounted in Ussing chambers, current required to maintain transepithelial potential difference at 0 mV (short circuit current, I(SC)) was monitored and effects of nucleotides upon I(SC) were studied. Mucosal UTP (100 microM) evoked a transient rise in I(SC) that was followed by a sustained fall below basal I(SC) maintained for 30 min. Mucosal ATP (100 microM) also stimulated a transient rise in I(SC) but in contrast to UTP did not inhibit basal I(SC). Submucosal UTP and ATP both transiently increased I(SC). UTP-prestimulated epithelia were refractory to ATP but prestimulation with ATP did not abolish the response to UTP. The epithelia thus appear to express two populations of apical receptors allowing nucleotides to modulate I(SC). The UTP-induced rise was reduced by pretreatment with either bumetanide (100 microM), diphenylamin-2-carboxylic acid (DPC, 1 mM), or Cl(-) and HCO(3)(-)-free solution whilst the fall was abolished by amiloride pretreatment. Thapsigargin (0.3 microM) abolished the UTP-induced increase in I(SC) but not the subsequent decrease. Staurosporine (0.1 microM) inhibited basal I(SC) and blocked UTP-induced inhibition of I(SC). Inhibitors of either protein kinase C (PKC) (D-erythro sphingosine) or PKA (H89) had no effect. This study suggests that UTP stimulates Cl(-) secretion and inhibits basal Na(+) absorption. ATP has a similar stimulatory effect, which may be mediated by activation of P2Y(2) receptors and an increase in [Ca(2+)](in), but no inhibitory effect, which is likely mediated by activation of a pyrimidine receptor and possible inhibition of a protein kinase other than PKC or PKA.

Effect of luminal nucleotides on Cl- secretion and Na+ absorption in distal bronchi

P2Y receptor agonists stimulate Cl- secretion across both normal and cystic fibrosis (CF) airway epithelia, and therefore have potential for use in the treatment of CF. Although CF pathology is manifest primarily in the distal airways, most studies of P2Y-receptor-mediated airway epithelial ion transport have used cells cultured from proximal regions. Here we report the results of studies of P2Y-receptor-mediated ion transport in distal bronchi isolated from porcine lungs, cannulated and perfused. A luminal microelectrode was used to record transepithelial potential difference (PD) and cable analysis was applied to determine resistance (Rt) and equivalent short-circuit current (I(SC)). Luminal UTP (100 micromol/l) transiently hyperpolarized PD (from -5.8+/-0.3 to -6.5+/-0.4 mV) and increased I(SC) (from 47+/-6 to 55+/-8 microA cm(-2)) before inhibiting PD to below the pre-UTP level (-5.0+/-0.4 mV). The decline was attenuated by pretreatment with amiloride, and additional treatment with bumetanide inhibited the initial hyperpolarization, suggesting that UTP stimulates Cl- secretion and inhibits Na+ absorption across distal bronchi. Luminal addition of P2Y1 [ADP, 2-methylthio-ATP (2MeSATP)] and P2Y6 (UDP) receptor agonists had no effect on ion transport. Pretreatment with thapsigargin (0.3 micromol/l) did not prevent the UTP-induced increase in PD and I(SC) but attenuated the secondary fall in PD. Pretreatment with BAPTA/AM (50 micromol/l), however, had no effect on the response to UTP. Additional studies of isolated bronchial epithelial cells using Fura-2 showed that UTP increases [Ca2+]in, and this increase is blocked by pretreatment with thapsigargin. These results suggest that in intact distal bronchi luminal UTP stimulates Cl- secretion by a Ca2+-independent mechanism and inhibits Na+ absorption by a Ca2+-dependent mechanism. Both effects are likely to favour increased hydration of the airway surface, and may therefore be beneficial in CF.

P2Y2 receptor-mediated inhibition of ion transport in distal lung epithelial cells

1 Rat foetal distal lung epithelial cells were plated onto permeable supports where they became integrated into epithelial sheets that spontaneously generated short circuit current (ISC). 2 Apical ATP (100 microM) evoked a transient fall in ISC that was followed by a rise to a clear peak which, in turn, was succeeded by a slowly developing decline to a value below control. Apical UTP evoked an essentially identical response. 3 UDP and ADP were ineffective whilst ATP had no effect when added to the basolateral solution. These effects thus appear to be mediated by apical P2Y2 receptors. 4 The rising phase of the responses to ATP/UTP was selectively inhibited by anion transport inhibitors but persisted in the presence of amiloride, which abolished the inhibitory effects of both nucleotides. Thus, apical nucleotides appear to evoke a transient stimulation of anion secretion and sustained inhibition of Na+ absorption. 5 Basolateral isoprenaline (10 microM) elicited a rise in ISC but subsequent addition of apical ATP reversed this effect. Conversely, isoprenaline restored ISC to its basal level following stimulation with ATP. Apical P2Y2 receptors and basolateral beta-adrenoceptors thus allow their respective agonists to exert mutually opposing effects on ISC.

Culture substrate-specific expression of P2Y2 receptors in distal lung epithelial cells isolated from foetal rats

ATP and UTP did not evoke [Ca2+]i signals in rat foetal lung epithelial cells grown on glass but elicited clear responses in cells grown into functionally polarised epithelia on permeable supports. Moreover, P2Y2 receptor mRNA could not be detected in cells on glass by the polymerase chain reaction but this mRNA species was clearly expressed by polarised cells. P2Y2 receptor expression thus appears to be a feature of the polarised phenotype.

Effect of anion secretion inhibitors on mucin content of airway submucosal gland ducts

In porcine bronchi, inhibition of both Cl- and HCO3- transport is required to block the anion secretion response to ACh and to cause mucus accumulation within ACh-treated submucosal gland ducts [S. K. Inglis, M. R. Corboz, A. E. Taylor, and S. T. Ballard. Am. J. Physiol. 272 (Lung Cell. Mol. Physiol. 16): L372-L377, 1997]. In this previous study, a combination of three potential HCO3- transport inhibitors [1 mM acetazolamide, 1 mM DIDS, and 0.1 mM dimethylamiloride (DMA)] was used to block carbonic anhydrase, Cl-/HCO3- exchange, and Na+/H+ exchange, respectively. The aim of the present study was to obtain a better understanding of the mechanism of ACh-induced HCO3- secretion in airway glands by determining which of the three inhibitors, in combination with bumetanide, is required to block anion secretion and so cause ductal mucin accumulation. Gland duct mucin content was measured in distal bronchi isolated from domestic pigs. Addition of either bumetanide alone, bumetanide plus acetazolamide, or bumetanide plus DIDS had no significant effect on ACh-induced mean gland duct mucin content. In contrast, glands treated with bumetanide plus DMA as well as glands treated with all four anion transport blockers were almost completely occluded with mucin after the addition of ACh. These data suggest that mucin is cleared from the ducts of bronchial submucosal glands by liquid generated from Cl(-)- and DMA-sensitive HCO3- transport.

Inhibition of airway liquid secretion and its effect on the physical properties of airway mucus

The combination of both Cl- and HCO3- secretion inhibitors causes an accumulation of mucins within the submucosal gland ducts of acetylcholine (ACh)-treated bronchi [S. K. Inglis, M. R. Corboz, A. E. Taylor, and S. T. Ballard. Am. J. Physiol. 272 (Lung Cell. Mol. Physiol. 16): L372-L377, 1997], suggesting indirectly that these agents block airway gland liquid secretion. The present study tested the hypotheses that ACh-stimulated liquid secretion is driven by Cl- and HCO3- secretion and that inhibition of this process leads to secretion of a dehydrated mucus with altered rheological properties. Excised distal bronchi from pigs were pretreated with either a combination of Cl- and HCO3- secretion inhibitors (bumetanide, acetazolamide, dimethylamiloride, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid) or the dimethyl sulfoxide vehicle and were then treated with ACh to induce secretion. The rate of mucus liquid secretion was substantially reduced when the airways were pretreated with the anion secretion inhibitors. Mucus liquid from inhibitor-pretreated airways contained almost threefold more nonvolatile solids than the control liquid. Rheological analysis revealed that mucus liquid from inhibitor-pretreated airways expressed a significantly greater log G* (rigidity factor), whereas tangent delta (recoil factor) was significantly reduced. These results suggest that 1) ACh-induced liquid secretion in bronchi is driven by both Cl- and HCO3- secretion and 2) inhibition of ACh-induced liquid secretion results in the secretion of mucus with a reduced water content and altered rheological properties.

Dilatory effect of furosemide on rat tracheal arterioles and venules

Furosemide pretreatment greatly reduces the severity of an asthmatic response to several types of bronchoconstrictor challenge. Indirect evidence suggests that furosemide exerts its protective effects by dilating the airway vasculature during thermal stress. To test the hypothesis that furosemide dilates airway microvessels, the tracheas of anesthetized rats were surgically exposed and continuously suffused with Krebs Ringer bicarbonate warmed to 37 degrees C. Tracheal adventitial arterioles (13.0 to 41.0 microns initial diameter, n = 47) and venules (50.0 to 99.0 microns initial diameter, n = 46) were visualized with a videomicroscope, and vessel diameters were measured using videocalipers. When vessels were preconstricted with 10(-4) M phenylephrine, a selective alpha 1-adrenergic agonist, and then treated with 10(-4) M furosemide, significant (p < 0.05) dilation was observed in both arterioles (from 64.6 to 79.5% of their initial diameter) and venules (from 52.1 to 65.4% of their initial diameter). When vessels were preconstricted with 10(-4) phenylephrine, after pretreatment with the cyclooxygenase inhibitor indomethacin (5.0 mg/kg), 10(-4) M furosemide significantly dilated arterioles (from 77.5 to 93.0% of their initial diameter) and venules (from 58.5 to 80.1% of their initial diameter). In vessels preconstricted with 10(-3) M L-NAME, an inhibitor of nitric oxide synthesis, addition of 10(-4) M furosemide to the suffusion still caused significant dilation in arterioles, from 77.4 to 88.8% of their initial diameter, and in venules from 79.5 to 86.7% of their initial diameter. These data confirm that furosemide, when applied topically, dilates tracheal arterioles and venules by cyclooxygenase- and nitric oxide-independent mechanisms.

Effect of anion transport inhibition on mucus secretion by airway submucosal glands

To model the airway glandular defect in cystic fibrosis (CF), the effect of anion secretion blockers on submucosal gland mucus secretion was investigated. Porcine distal bronchi were isolated, pretreated with a Cl- secretion blocker (bumetanide) and/or a combination of blockers to inhibit HCO3- secretion (dimethylamiloride, acetazolamide, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid), and then treated with acetylcholine (ACh), a glandular liquid and mucus secretagogue. Bronchi were then fixed, sectioned, and stained for mucins. Each gland duct was ranked for mucin content from zero (no mucin) to five (duct completely occluded with mucin). Untreated bronchi, bronchi treated only with ACh, and ACh-treated bronchi that received either bumetanide or the HCO3- secretion blockers all exhibited low gland duct mucin content (1.18 +/- 0.34, 0.59 +/- 0.07, 0.65 +/- 0.03, and 0.83 +/- 0.11, respectively). However, pretreatment with both Cl- and HCO3- secretion blockers before ACh addition resulted in substantial and significant ductal mucus accumulation (3.57 +/- 0.22). In situ videomicroscopy studies of intact airways confirmed these results. Thus inhibition of the anion (and presumably liquid) secretion response to ACh leads to mucus obstruction of submucosal gland ducts that resembles the early pathological changes observed in CF.

In situ visualization of bronchial submucosal glands and their secretory response to acetylcholine

Airway submucosal glands secrete both macromolecules and liquid, yet the mechanisms by which these substances are secreted are not well understood. In this study, a video microscope was used to directly visualize the submucosal glands in isolated porcine distal bronchi and to observe their responses to acetylcholine (ACh), a glandular secretagogue. Submucosal glands were classified as either "antral," "linear," or "convoluted" glands based on the morphology of their terminal collecting ducts. Because antral duct glands were most easily visualized, the response to ACh was studied in detail in this gland type. Within 5-10 s after addition of 10 microM ACh, the cross-sectional area of the gland duct openings to the airway surface increased severalfold but returned to pre-ACh dimensions within 1 min. Between 30 s and 10 min after ACh addition, spherical particles (1-10 microm) entered the antral ducts from distal acini and exited through the duct openings to the airway surface. Some of the particles were retained within the antral duct where they were kept in constant motion by the action of cilia present within the antral duct. The particles, which are likely to contain the macromolecular secretory products of mucous and/or serous cells, maintained their spherical shape within the gland duct, suggesting that the secretion product was membrane bound. To our knowledge, these studies provide the first description of airway submucosal gland secretion as viewed in situ.

Tracheal microvascular responses to inhibition of nitric oxide synthesis in anesthetized rats

We previously demonstrated that rat tracheal arterioles and large venules constrict in response to alpha-adrenergic agonists and dilate in response to beta-adrenergic agonists. To further investigate the vasodilatory mechanisms in these vessels, we hypothesized that the vascular tone in the tracheal microcirculation is regulated in part by endogenously released nitric oxide (NO). To test this hypothesis, rat tracheal microvessels were visualized in vivo with a video microscope. The change in diameter af adventitial arteriolar (14.5 to 42.0 microm initial diameter, n = 41) and large venular (50.0 to 100.0 microm initial diameter, n = 41) microvessels following the suffusion of vasoactive drugs was measured with video calipers. Significant constriction was observed in arterioles (to 70.0% of initial diameter) and large venules (to 76.6% of initial diameter) after 20 min of suffusion with L-NAME, an inhibitor of NO synthesis. This constriction was in large part reversed by L-arginine, a biochemical precursor of NO, in arterioles (to 93.2% of initial diameter) and in venules (to 90.8% of initial diameter). The combination of prazosin, a selective alpha1-adrenergic antagonist, and yohimbine, a selective alpha2-adrenergic antagonist, also reduced L-NAME-induced constriction in arterioles (to 87.9% of initial diameter) and in venules (to 85.2% of initial diameter). L-arginine or the combination of prazosin and yohimbine alone did not affect the diameter of tracheal microvessels. These data suggest that NO exerts an important influence on tracheal microvascular tone in rats, and may attenuate alpha-adrenergic constriction in these vessels.

Tracheal microvascular responses to beta-adrenergic stimulation in anesthetized rats

Previous study of adrenergic control of the tracheal vasculature in rats (1) demonstrated that beta-adrenergic blockade heightened arteriolar and large venular contractile responses to norepinephrine, a nonselective alpha-adrenergic agonist. The present study was undertaken to confirm the presence of functional beta-adrenergic receptors and to determine which beta-adrenergic receptor subtypes mediate vasodilation in this tissue. Tracheal adventitial arterioles (12.0 to 47.0 micro m initial diameter, n=39) and venules (48.0 to 98.5 micrometers initial diameter, n=44) were observed through a video microscope, and vessel diameters were measured. Vessels were preconstricted with 10(-4) M phenylephrine (PHE), a selective alpha 1-adrenergic agonist, to achieve sufficient tone for measurement of dilation responses. When vessels were treated only with PHE, arterioles and venules constricted to 55.9% and 67.6% of their initial diameter, respectively, after 15 min of suffusion. When preconstricted vessels were treated with the nonselective beta-adrenergic agonist isoproterenol (10(-5) M), both arterioles and venules significantly dilated from 63.4% to 82.9% and from 71.5% to 81.3% of their initial diameters. At high concentration (10(-5) M), the putative beta 2-adrenergic agonist terbutaline also caused preconstricted arterioles and venules to significantly dilate from 70.8% to 79.8% and from 71.5% to 83.4% of their initial diameters. The selective beta 1-adrenergic antagonist atenolol (10(-6) M) did not affect terbutaline-induced dilation in preconstricted arterioles, but greatly attenuated dilation in preconstricted venules. From these data, we conclude that beta 2-adrenergic receptors are present in and mediate dilation of tracheal arterioles, and also, that the dilation in large tracheal venules is mediated in large part through beta 1-adrenergic receptors.

Regulation of ion transport across porcine distal bronchi

Distal airways comprise the vast majority of total human airway surface area, yet little is known about transepithelial ion transport in these tissues. Pathways that regulate ion transport in porcine small bronchi (3.62 +/- 0.04 mm outer diameter) were studied by measuring the effects of secretogogues that stimulate Cl- secretion in proximal airways. Resting potential difference (PD), shortcircuit current (ISC), and resistance (Rt) across the distal bronchi were 3.4 +/- 0.1 mV (lumen negative), 40.8 +/- 1.7 microA/cm2, and 92.1 +/- 5.0 omega.cm2, respectively. Isoproterenol (10 microM), acetylcholine (ACh; 10 microM), or ATP (100 microM) induced immediate significant (P < 0.05) increases in PD and ISC. The Ca2+ ionophore A23187 (1 microM) induced a slow increase in PD that was accompanied by a significant 2.4-fold increase in Rt and no change in ISC. The responses to isoproterenol, ACh, and ATP were maintained in the presence of 10 microM amiloride. Pretreatment with 10 microM bumetanide to block Cl- secretion inhibited responses to isoproterenol and ATP but not to ACh. The ACh effect was inhibited only after both Cl- and HCO3- secretion were blocked. These data suggest that isoproterenol, ACh, and ATP stimulate anion secretion. Isoproterenol and ATP specifically stimulate Cl- secretion, whereas ACh can stimulate both Cl- and HCO3- secretion. A23187 has no effect on active transepithelial ion transport but increases barrier resistance in intact distal bronchial epithelium.

Chloride secretion across distal airway epithelium: relationship to submucosal gland distribution

To evaluate the possible relationship between submucosal glands and transepithelial Cl- secretion, we compared the bioelectric properties of two distal airway regions: bronchioles, which contain few submucosal glands, and small bronchi, which contain numerous glands. Intact distal bronchi were dissected from the lungs of 4-8 wk old pigs and cannulated with micropipettes and perfused. Transepithelial potential difference (PD), short-circuit current (Isc), and barrier resistance (Rm) in distal bronchi, determined by cable analysis, were -3.0 +/- 0.4 mV, 50.7 +/- 5.9 microA/cm2, and 59.6 +/- 5.9 omega.cm2, respectively (means +/- SE). Bumetanide (10 microM), which blocks Cl- secretion through inhibition of Na(+)-K(+)-2Cl- cotransport, reduced Isc in distal bronchi by 30.0 +/- 5.5 microA/cm2 (59.0% of the total Isc). By comparison, a previous study of porcine distal airways [S.T. Ballard and A.E. Taylor, Am. J. Physiol. 267 (Lung Cell. Mol. Physiol. 11): L79-L84, 1994] determined that bumetamide-sensitive Isc in bronchioles was 2.6 +/- 1.4 microA/cm2 (only 9.0% of the total Isc). Submucosal gland duct openings to the luminal surface were identified microscopically and counted in representative fields. In eight bronchioles, 6.8 +/- 4.4 gland duct openings/cm2 of airway surface were observed, whereas seven distal bronchi contained 916.8 +/- 84.0 gland duct openings/cm2, over a 100-fold difference. These data suggest that a direct relationship may exist between the magnitude of active transepithelial Cl- secretion and the presence of submucosal glands in normal distal airways.