The prospective evaluation of the TB strain typing service in England: a mixed methods study.

BACKGROUND: In response to rising TB notification rates in England, universal strain typing was introduced in 2010. We evaluated the acceptability, effectiveness and cost-effectiveness of the TB strain typing service (TB-STS). METHODS: We conducted a mixed-methods evaluation using routine laboratory, clinic and public health data. We estimated the effect of the TB-STS on detection of false positive Mycobacterium tuberculosis diagnoses (2010-2012); contact tracing yield (number of infections or active disease per pulmonary TB case); and diagnostic delay. We developed a deterministic age-structured compartmental model to explore the effectiveness of the TB-STS, which informed a cost-effectiveness analysis. RESULTS: Semi-structured interviews explored user experience. Strain typing identified 17 additional false positive diagnoses. The TB-STS had no significant effect on contact tracing yield or diagnostic delay. Mathematical modelling suggested increasing the proportion of infections detected would have little value in reducing TB incidence in the white UK-born population. However, in the non-white UK-born and non-UK-born populations, over 20 years, if detection of latent infection increases from 3% to 13% per year, then TB incidence would decrease by 11%; reducing diagnostic delay by one week could lead to 25% reduction in incidence. The current TB-STS was not predicted to be cost-effective over 20 years (£95 628/quality-adjusted life-years). Interviews found people had mixed experiences, but identified broader benefits, of the TB-STS. CONCLUSIONS: To reduce costs, improve efficiency and increase effectiveness, we recommend changes to the TB-STS, including discontinuing routine cluster investigations and focusing on reducing diagnostic delay across the TB programme. This evaluation of a complex intervention informs the future of strain typing in the era of rapidly advancing technologies.

Toxicology study assessing efficacy and safety of repeated administration of lipid/DNA complexes to mouse lung.

For gene therapy to improve lung function in cystic fibrosis (CF) subjects, repeated administration of the gene transfer agent over the lifetime of patients is likely to be necessary. This requirement limits the utility of adenoviral and adeno-associated viral vectors (both previously evaluated in CF gene therapy trials) because of induced adaptive immune responses that render repeated dosing ineffective. For CF gene therapy trials, non-viral vectors are currently the only viable option. We previously showed that the cationic lipid formulation GL67A is the most efficient of several non-viral vectors analysed for airway gene transfer. Here, we assessed the efficacy and safety of administering 12 inhaled doses of GL67A complexed with pGM169, a CpG-free plasmid encoding human CFTR complementary DNA, into mice. We show that repeated administration of pGM169/GL67A to murine lungs is feasible, safe and achieves reproducible, dose-related and persistent gene expression (>140 days after each dose) using an aerosol generated by a clinically relevant nebuliser. This study supports progression into the first non-viral multidose lung trial in CF patients.

Pre-clinical evaluation of three non-viral gene transfer agents for cystic fibrosis after aerosol delivery to the ovine lung.

We use both large and small animal models in our pre-clinical evaluation of gene transfer agents (GTAs) for cystic fibrosis (CF) gene therapy. Here, we report the use of a large animal model to assess three non-viral GTAs: 25 kDa-branched polyethyleneimine (PEI), the cationic liposome (GL67A) and compacted DNA nanoparticle formulated with polyethylene glycol-substituted lysine 30-mer. GTAs complexed with plasmids expressing human cystic fibrosis transmembrane conductance regulator (CFTR) complementary DNA were administered to the sheep lung (n=8 per group) by aerosol. All GTAs gave evidence of gene transfer and expression 1 day after treatment. Vector-derived mRNA was expressed in lung tissues, including epithelial cell-enriched bronchial brushing samples, with median group values reaching 1-10% of endogenous CFTR mRNA levels. GL67A gave the highest levels of expression. Human CFTR protein was detected in small airway epithelial cells in some animals treated with GL67A (two out of eight) and PEI (one out of eight). Bronchoalveolar lavage neutrophilia, lung histology and elevated serum haptoglobin levels indicated that gene delivery was associated with mild local and systemic inflammation. Our conclusion was that GL67A was the best non-viral GTA currently available for aerosol delivery to the sheep lung, led to the selection of GL67A as our lead GTA for clinical trials in CF patients.

Ventilation heterogeneity in children with well controlled asthma with normal spirometry indicates residual airways disease.

BACKGROUND: In adults with asthma, ventilation heterogeneity, independent of inflammation, has been hypothesised to be associated with airway remodelling. Bronchial biopsy in preschool children with wheeze demonstrates early structural changes. Ventilation heterogeneity is sensitive to airway disease in other paediatric respiratory conditions such as cystic fibrosis, so may be sensitive to early airway disease in asthma. An observational study was performed in which it was hypothesised that ventilation heterogeneity (lung clearance index (LCI) and phase III slope indices (S(cond) and S(acin))) were more sensitive than conventional measurements (forced expiratory volume in 1 s (FEV(1)) and exhaled nitric oxide (Feno)) for detecting residual airways disease in children with well controlled asthma. METHODS: In 31 children with asthma of mean age 10.6 years (range 5-15), FEV(1), LCI, S(cond) and S(acin) were measured at two separate visits, before and after blinded salbutamol or placebo, with Feno measured once. 29 healthy volunteers of mean age 11.2 years (range 5-16) completed measurements at one visit only. RESULTS: Baseline mean (SD) LCI was significantly higher in children with asthma than in controls (6.69 (0.91) vs 6.24 (0.47), p = 0.02). There were no significant differences in FEV(1) or median Feno. Following salbutamol there was a small significant change in mean (SD) FEV(1) (from -1.26 (1.25) to -0.93 (0.23), p = 0.03) but not in LCI, S(cond) or S(acin). Importantly, LCI remained significantly higher after bronchodilator in children with asthma than in controls (6.64 (0.69), p = 0.01). CONCLUSION: This study identifies the presence of residual ventilation heterogeneity in children with well controlled asthma and normal FEV(1). The role of LCI in measuring early airway disease in children with asthma requires further exploration, possibly as a surrogate of structural remodelling.

Lung clearance index is a sensitive, repeatable and practical measure of airways disease in adults with cystic fibrosis.

BACKGROUND: Lung clearance index (LCI) is a sensitive marker of early lung disease in children but has not been assessed in adults. Measurement is hindered by the complexity of the equipment required. The aims of this study were to assess performance of a novel gas analyser (Innocor) and to use it as a clinical tool for the measurement of LCI in cystic fibrosis (CF). METHODS: LCI was measured in 48 healthy adults, 12 healthy school-age children and 33 adults with CF by performing an inert gas washout from 0.2% sulfur hexafluoride (SF6). SF6 signal:noise ratio and 10-90% rise time of Innocor were compared with a mass spectrometer used in similar studies in children. RESULTS: Compared with the mass spectrometer, Innocor had a superior signal:noise ratio but a slower rise time (150 ms vs 60 ms) which may limit its use in very young children. Mean (SD) LCI in healthy adults was significantly different from that in patients with CF: 6.7 (0.4) vs 13.1 (3.8), p<0.001. Ten of the patients with CF had forced expiratory volume in 1 s > or = 80% predicted but only one had a normal LCI. LCI repeats were reproducible in all three groups of subjects (mean intra-visit coefficient of variation ranged from 3.6% to 5.4%). CONCLUSIONS: Innocor can be adapted to measure LCI and affords a simpler alternative to a mass spectrometer. LCI is raised in adults with CF with normal spirometry, and may prove to be a more sensitive marker of the effects of treatment in this group.

Validation of beat by beat pulsed Doppler measurements of ascending aortic blood velocity in man.

The volume, velocity, and acceleration of ascending aortic blood were measured in man using a pulsed Doppler ultrasound instrument, with online spectral analysis and offline computer processing of velocity data. This system was firstly validated in a test rig capable of generating pulsatile flow of talc particles in water at physiological velocities and accelerations in a model aorta. Doppler measurements correlated well (r greater than or equal to 0.90) with simultaneous electromagnetic measurements of stroke volume, peak ejection velocity, and maximum acceleration in this rig. In vivo validation was performed firstly by comparing simultaneous Doppler and thermodilution cardiac output (Q) measurements; this yielded the following regression equation: Doppler Q = 0.90 X thermodilution Q + 0.03 litre.min-1, r = 0.92; n = 38. Beat by beat measurements were then validated against simultaneous invasive aortic blood velocity measurements made using a Mills electromagnetic cathetertip probe. When paced single beats of different size were compared within subjects the correlation coefficients between Doppler and electromagnetic measurements averaged 0.89 for stroke volume, 0.91 for peak ejection velocity, and 0.79 for maximum acceleration in five subjects. The absolute values for velocity and acceleration from the Doppler system differed significantly from the absolute values given by the electromagnetic system and this difference was not consistent between subjects. It is concluded that the Doppler system can non-invasively record relative changes in left ventricular ejection in man.

Reflex pharyngeal dilator muscle activation by stimuli of negative airway pressure in awake man.

This paper summarizes evidence for reflex genioglossus muscle activation by stimuli of negative airway pressure in normal, awake human subjects. Stimuli of negative airway pressure (range -5 to -35 cm H2O) caused activation of the genioglossus muscle. The larger values of negative pressure gave larger responses. Response latencies (median = 34 milliseconds) were much faster than the time for voluntary muscle activation (median = 184 milliseconds), suggesting that the responses were reflex in origin. The reflex nature of the responses was confirmed by studies with local anesthetics. The trigeminal, superior laryngeal and the glossopharyngeal nerves all mediated a component of the responses observed from the upper airway.

Atopy influences exhaled nitric oxide levels in adult asthmatics.

STUDY OBJECTIVE: To examine whether atopy influences exhaled nitric oxide (NO) levels in adults with established asthma. SETTING: Specialist respiratory unit in a university teaching hospital. PATIENTS: Twenty-eight asthmatics (mean FEV(1), 85.7%) receiving short-acting inhaled bronchodilators and a range of inhaled steroids (0 to 4,000 microg/d). INTERVENTIONS: Subjects were studied on two occasions, 5 to 7 days apart, between September and March. MEASUREMENTS AND RESULTS: On the first day, FEV(1), exhaled NO, and histamine challenge were performed. On the second day, exhaled NO, total IgE, and skin-prick testing to six common allergens were conducted. Exhaled NO was measured with the single exhalation method. We found exhaled NO levels to correlate positively with total IgE (r = 0.43, p = 0.02) and number of positive skin-prick tests (p = 0. 002). By contrast, there was no significant correlation between exhaled NO and FEV(1) or the provocative concentration causing a 20% fall in FEV(1). Subanalyses of steroid-treated and steroid-naive patients in this group revealed the same findings. CONCLUSION: Exhaled NO levels in asthmatics correlate more closely with atopy than with bronchial hyperreactivity and lung function.

Respiration during recovery from exercise: effects of trapping and release of femoral blood flow.

To investigate the contribution of vascular and metabolic stimuli to the sustained hyperpnea after exercise, the respiratory effects of obstructing and then releasing the femoral blood flow were recorded in 15 normal volunteers during recovery from steady-state cycle exercise (80 W). Obstruction was achieved using cuffs around the upper thighs, inflated for the first 2 min of recovery to a pressure of 200 mmHg. Cuff inflation significantly reduced ventilation during recovery compared with control (P less than 0.001); the subsequent release of pressure was accompanied by an increase in ventilation (averaging 3.2 l/min), which began on the first breath after release. This preceded a rise in end-tidal CO2 (maximum 8.3 Torr increase), which first became significant on the fourth breath after release and led to a further rise in ventilation. The first-breath increase in ventilation after cuff release persisted, although slightly attenuated (averaging 2.5 l/min), in additional experiments with inspired O2 fraction of 1.0. The pattern of ventilatory response was also similar when the experiments were performed with 5% CO2 in air as the inspirate. The immediate rise in ventilation on cuff release, together with the persistent response on 100% O2, suggests that the vascular changes resulting from cuff release exert an influence on ventilation independent of the effects of released metabolites on the known chemoreceptors. The persistence of the response on 5% CO2 indicates that CO2-sensitive lung afferents do not have a major role in these responses.

Central and reflex neural control of genioglossus in subjects who underwent laryngectomy.

Inspiratory activation of the genioglossus (GG) may occur by central drive or as a reflex to negative airway pressure. To distinguish between these, we studied seven laryngectomy patients who breathe via tracheal stomas. Negative pressure stimuli (-15 and -25 cmH2O for 500 ms) were applied 1) at functional residual capacity and 2) during early inspiration via (i) the upper airway (UA) and (ii) the tracheal stoma. Intraoral surface GG electromyogram was quantified, as described previously (R. L. Horner, J. A. Innes, K. Murphy, and A. Guz, J. Physiol. Lond. 436: 15-29, 1991). Phasic GG activity was also measured from an integrated electromyogram during spontaneous and inspiratory loaded breathing. Reflex GG activation occurred with negative UA pressure both at functional residual capacity and during inspiration (P < 0.001), but pressure stimuli at the stoma caused no significant activation (P = 0.07). Phasic inspiratory activation occurred in four patients at rest and in all seven patients during inspiratory loading (P < 0.02). These patients demonstrate 1) reflex activation of the GG by negative UA pressure without airflow or respiratory effort and 2) central inspiratory GG activation that is not mediated by negative airway pressure.

Inspiratory coactivation of the genioglossus enlarges retroglossal space in laryngectomized humans.

To investigate the relationship between the electrical activity of the genioglossus (GG-EMG) and associated tongue movement, seven laryngectomized subjects breathing through a tracheal stoma (without pressure or flow change in the upper airway) were studied in the supine position. Tongue movement, with the use of lateral fluoroscopy, and GG-EMG expressed as a percentage of maximum voluntary genioglossal activation were monitored simultaneously during 1) spontaneous inspiration (SI), 2) resistive loaded inspiration (LI), and 3) rapid inspiration (RI). Tongue position during each maneuver was compared with its position during spontaneous expiration. Peak GG-EMG during the three maneuvers was significantly different from each other (SI: 5.4 +/- 1.6, LI: 11.9 +/- 1.8, and RI: 51.6 +/- 9.4 (SE) %, respectively). Associated forward movement of the posterior aspect of the tongue was minimum during SI; however, significant movement was observed during LI, and this was increased during RI. Significant covariance existed between peak GG-EMG and this movement. Genioglossal coactivation with inspiration enlarges the glossopharyngeal airway, particularly in its caudal part. In subjects with intact upper airways, this activation may protect or enhance upper airway patency in an effort-dependent manner.

An outbreak of tuberculosis in a children's hospital.

A 3-year-old girl was admitted to a children's hospital; subsequently her mother was found to have pulmonary tuberculosis with smear-positive sputum. Of over 400 patients, their families and staff at risk in the hospital, 30 inpatients, three outpatients, two sibling visitors and one staff member became infected. A retrospective cohort study of exposed inpatients identified exposure duration, exposure proximity and primary diagnosis as independent predictors of infection risk. Children with neoplastic disease who were being treated with cytotoxic and immunosuppressive therapy with clotting factors were at a greater risk of developing clinical disease including disseminated infection. Altogether three generations of infected children and adults were diagnosed amongst community and hospital contacts in this extended outbreak. These findings support current recommendations for the follow-up of highly susceptible casual contacts of cases of pulmonary tuberculosis with smear-positive sputa.

Seasonality of presentation of imported Plasmodium vivax malaria in Birmingham, UK.

Residents of the UK returning from northern Pakistan with Plasmodium vivax infection tend to develop symptoms and present to hospital in the summer months, irrespective of the month of return. Thus, infections acquired in the cooler months of November to April appear to have a longer latency before presentation. Experiments suggest that more hypnozoites arise from the liver when ambient temperatures fall, somehow 'programming' parasites within biting mosquitoes.

Inappropriate inhaler use: assessment of use and patient preference of seven inhalation devices. EDICI.

Inefficient inhaler technique is a common problem resulting in poor drug delivery, decreased disease control and increased inhaler use. The aim of this study was to assess patients' use of different inhaler devices and to ascertain whether patient preference is indicative of ease of use and whether current inhaler use has any influence on either technique or preference. We also wished to define the most appropriate method of selecting an inhaler for a patient, taking into account observed technique and device cost. One hundred patients received instruction, in randomized order, in the use of seven different inhaler devices. After instruction they were graded (using predetermined criteria) in their inhaler technique. After assessment patients were asked which three inhalers they most preferred and which, if any, they currently used. Technique was best using the breath-actuated inhalers; the Easi-Breathe and Autohaler, with 91% seen to have good technique. The pressurized metered dose inhaler (pMDI) fared poorly, in last position with only 79% of patients showing good technique, despite being the most commonly prescribed. The Easi-Breathe was by far the most popular device with the patients. The Autohaler came in second position closely followed by the Clickhaler and Accuhaler. The majority of patients (55%) currently used the pMDI but the pMDI did not score highly for preference or achieve better grades than the other devices. Only 79% of patients tested could use the pMDI effectively even after expert instruction yet it continues to be commonly prescribed. This has important repercussions for drug delivery and hence disease control. Prescribing a patient's preferred device increases cost but can improve efficiency and therefore be cost effective in the long term. Using an inexpensive device (pMDI) when technique is good and the patient's preferred inhaler device when not is one way to optimize delivery and may even reduce cost.

The effect of perioperative adriamycin on skin-graft take and adherence in the rat.

This two-part study was undertaken to evaluate the effect of perioperative Adriamycin on skin-graft take and adherence in an animal model. Thirty-four male Fisher rats were divided into control and experimental groups. The controls received intravenous saline, and the experimental animals received Adriamycin 6 mg/kg (LD 10) 24 hours preoperatively. Each animal was then grafted with an autogenous split-thickness skin graft on a contiguous dermal and fascial bed. Skin-graft take was judged and measured at 7 and 14 days postoperatively. The average skin-graft take for controls was 6.1 cm2 on both the dermal and fascial beds. This was significantly better than the average skin-graft take sustained by the experimental groups of 4.3 and 3.5 cm2 on the dermal and fascial beds, respectively (p less than 0.01). Another 30 animals were divided into three control and three experimental groups. They were treated with saline and Adriamycin as before, and they underwent a similar surgical procedure. Skin-graft adherence, which was measured at 12, 24, and 48 hours postoperatively, was significantly less in the experimental groups compared with the control groups at all times measured. These data suggest that a single supratherapeutic dose of Adriamycin given preoperatively decreases skin graft take in the experimental model studied and that this decrease may be the result of a concomitant decrease in graft adherence.

Serum protein analysis and bone marrow cytology in patients with an extreme elevation of the erythrocyte sedimentation rate.

One hundred patients in whom an Erythrocyte Sedimentation Rate (ESR) in excess of 100 mm. in the first hour was found on 2 consecutive occasions were investigated. Serum protein electrophoresis was performed on 96 of these patients and bone marrow examination on 55 patients. Acute infection was the commonest diagnosis though the majority of patients had 2 or more separate conditions each contributing to the elevation of the ESR. Quantitive serum protein electrophoresis was abnormal in all but one patient and was of limited diagnostic value. A definite band in the globulin region was detected in 11 patients, 7 of whom were found to have myelomatosis. Bone marrow examination was useful only in patients with a discrete band in the globulin fraction or with a specific haematological abnormality. It is suggested, therefore, that bone marrow examination be confined to patients with such abnormalities irrespective of an elevation of their ESR.

Lung clearance index: evidence for use in clinical trials in cystic fibrosis.

The ECFS-CTN Standardisation Committee has undertaken this review of lung clearance index as part of the group's work on evaluation of clinical endpoints with regard to their use in multicentre clinical trials in CF. The aims were 1) to review the literature on reliability, validity and responsiveness of LCI in patients with CF, 2) to gain consensus of the group on feasibility of LCI and 3) to gain consensus on answers to key questions regarding the promotion of LCI to surrogate endpoint status. It was concluded that LCI has an attractive feasibility and clinimetric properties profile and is particularly indicated for multicentre trials in young children with CF and patients with early or mild CF lung disease. This is the first article to collate the literature in this manner and support the use of LCI in clinical trials in CF.

Pneumothorax in cystic fibrosis: prevalence and outcomes in Scotland.

BACKGROUND: Pneumothorax is a feared complication of cystic fibrosis. With improved survival into adult life the incidence of pneumothorax is expected to increase. The optimal management of these patients is unclear. METHODS: Case review of patients from the three Scottish adult CF centres. RESULTS: A total of 22 episodes of pneumothorax occurred in 20 patients over a 12year period. 2 patients died as a result of the pneumothorax. 16 pneumothoraces were treated by insertion of an intercostal drain and 8 by observation. 8 patients suffered a prolonged air leak. 5 patients were treated with pleurodesis. Pneumothorax was associated with a small decline in lung function which persisted for at least 1year. CONCLUSION: Pneumothorax can present a challenge to treat in adult CF. However successful outcomes can be achieved even in cases of prolonged air leaks. Current national guidelines help in selecting optimal pleural interventions.