Biocide resistance in Acinetobacter baumannii: appraising the mechanisms

A global upsurge in antibiotic-resistant Acinetobacter baumannii requires supervised selection of biocides and disinfectants to avert nosocomial infections by reducing its spread. Moreover, inadequate and improper biocides have been reported as a contributing factor in antimicrobial resistance. Regardless of the manner of administration, a biocidal concentration that does not kill the target bacteria creates a stress response, propagating the resistance mechanisms. This is an essential aspect of the disinfection programme and the overall bio-contamination management plan. Knowing the mechanisms of action of biocides and resistance modalities may open new avenues to discover novel agents. This review describes the mechanisms of action of some biocides, resistance mechanisms, and approaches to study susceptibility/resistance to these agents.

The future of cardiac prognostication: supervised machine learning to predict mortality in patients with acute pulmonary embolism

Background

Pulmonary embolism (PE) is a significant cause of morbidity and hospitalization worldwide with Right Ventricular (RV) dysfunction identified in association with morality. Two-dimensional speckle tracking echocardiography is an imaging modality used to calculate cardiac strain which can be used to identify early mechanical stress in the RV.

Purpose

Combining imaging techniques with patient demographics, comorbidities, and clinical parameters, we aim to create a supervised machine learning model to predict mortality within one year after PE and identify important variables.

Methods

A retrospective cohort of 74 patients who presented with acute PE, confirmed by contrast CT or V/Q scanning, to our hospital system in 2017 who had a transthoracic echocardiogram within 48 hours after the event. STE was used to calculate Endocardial Global Longitudinal Strain (Endo-GLS), End-Diastolic Area (EDA), End-Systolic Area (ESA), and Fractional Area Change (FAC). These parameters were taken along with Size/location of PE, RV size, RV Function, RV Systolic Pressure (RVSP), and TR Velocity. A supervised machine learning model was created using logistic regression and random forest classifier algorithm 100 trees with bootstrapping using Python version 3.7.2. The data was randomly sampled and run through our classifier 50 times which our outcome measurements averaged.

Results

We identified Endo-GLS as the parameter with the highest weight (30.9%) followed by, FAC (14.0%), and ESA (10.8%). Non-echocardiographic variables that had high importance were patients BMI and Intervention at time of event. We found an Accuracy of 84.3%, Sensitivity of 57.1%, and Specificity of 91.5%. The AUC for our model was 0.87.

Conclusion

The use of novel imaging methods and supervised machine learning can help identify important variables such as Endo-GLS and help predict mortality in patients with PE. Extrapolated, strain patterns can be sensitively measured in the acute setting of diseases and be used to help predict clinical outcomes. Our next steps are to obtain larger sample size in to create a more robust classifier and to prospectively validate our model.

Random Forest Model

Funding Acknowledgement

Type of funding source: None

Campylobacter jejuni and Campylobacter coli in cecum contents of chickens of slaughter age: A microbiological surveillance

The presence of foodborne pathogens is a major concern for the food industry and increase in antibiotic resistance adds to the seriousness of this issue. Epidemiological studies have shown that there is little or no information from Iran on the prevalence of Campylobacter spp. in chickens of slaughter age. The aim of this study was to determine the prevalence, antibacterial susceptibility and type of Campylobacter species isolated from the cecum of chickens bred in Saqqez city, Kurdistan, western Iran. Campylobacter was isolated and identified by culture and molecular methods. Antibiotic susceptibility of Campylobacter species was performed by disk agar diffusion test and agar dilution methods. The bacterial isolates were typed by repetitive element sequence based polymerase chain reaction (rep-PCR) method. Fifty-five percent of the farms were found to be contaminated with Campylobacter spp. Gene amplification assay confirmed 67 isolates with Campylobacter spp., of which 57 (85.1%) were identified as C. jejuni and 10 (14.9%) as C. coli. Resistance to tetracycline was the most common finding (70.6%), followed by ciprofloxacin (63.7%) and amoxicillin (27.5%). All isolates retained their susceptibility towards gentamicin and meropenem. Results of MIC₅₀ and MIC₉₀ confirmed high resistance towards tetracycline and ciprofloxacin. Repetitive element sequence based-polymerase chain reaction (rep-PCR) placed C. jejuni in six profiles, while C. coli could not be separated as diverse clones. The present study focused on obtaining data regarding prevalence, antibiotic susceptibilities, genetic diversity at regular intervals and maintain and improve hygiene. The results of this study showed substantial genetic diversity of C. jejuni in chickens from western Iran.

Comparison of the application of lidocaine, lidocaine-dexamethasone and lidocaine-epinephrine for caudal epidural anesthesia in cows

The aim of the present study was to determine whether the addition of dexamethasone or epinephrine to lidocaine altered the characteristics of anesthesia and cardiorespiratory variables following caudal epidural application in cows. Twenty adult dairy cows were randomly assigned to receive one of the treatments of lidocaine (LID, 0.2 mg/kg), dexamethasone (DEX, 8 mg), lidocaine-dexamethasone (LIDEX; 0.2 mg/kg and 8 mg, respectively) and lidocaine-epinephrine (LIDEP; 0.2 mg/kg and 5 µg/ml, respectively) by epidural injection with the final volume of 0.018 ml/kg and 10 ml of solution as the upper limit. The time to the onset and duration of anesthesia as well as heart rate (HR), respiratory rate (f _R) and rectal temperature (RT) were recorded. No local anesthetic effects were observed in DEX. The onset of anesthesia did not show significant differences among LID, LIDEX and LIDEP. The duration of anesthesia was significantly longer in LIDEX (152.4 ± 25.8 min) as compared to LID (116.0 ± 11.5 min). Although the duration of anesthesia in LIDEP (137.7 ± 10.0 min) was longer in comparison to LID, the difference was not statistically significant. There was no significant difference regarding the onset and duration of anesthesia between LIDEX and LIDEP. HR, f _R and RT did not show significant changes over time. Mild transient ataxia was observed in groups that received lidocaine-containing solutions. In conclusion, addition of dexamethasone to lidocaine, without altering the time to onset, produced more prolonged anesthesia than that of lidocaine alone following caudal epidural application in cows.

Diagnostic value of cone beam computed tomography and panoramic radiography in predicting mandibular nerve exposure during third molar surgery

The aim of this study was to evaluate the diagnostic accuracies of cone beam computed tomography (CBCT) and panoramic techniques in predicting inferior alveolar nerve (IAN) exposure. The sample size was determined based on a pilot study. This prospective clinical series study included 59 third molar extraction sites with any of seven previously suggested panoramic signs of IAN exposure. The diagnosis of nerve exposure was done on panoramic and CBCT images. Molars were extracted and nerve exposure was evaluated clinically. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CBCT method, and sensitivity and PPV of panoramic method were estimated). The panoramic and CBCT methods correctly classified 67.7% and 93.3%, respectively, of 60 cases. This difference was statistically significant (χ²=13.333, P=0.000). The sensitivity, specificity, PPV, and NPV for CBCT were 97.4%, 85.7%, 92.7%, and 94.7%, respectively. The sensitivity and PPV of panoramic radiography were 67.8% and 97.6%, respectively. The signs with the highest sensitivity were interruption of the mandibular canal border and abrupt canal narrowing. None of the Pell and Gregory criteria, molar angulations, or three-dimensional canal-apex relationships was significantly associated with clinically confirmed IAN exposure. Panoramic radiography may miss about one-third of exposure cases, but a positive panoramic diagnosis is most likely to be a real exposure and should be taken seriously.

A phase 1b clinical trial of the CD40-activating antibody CP-870,893 in combination with cisplatin and pemetrexed in malignant pleural mesothelioma

BACKGROUND

Data from murine models suggest that CD40 activation may synergize with cytotoxic chemotherapy. We aimed to determine the maximum tolerated dose (MTD) and toxicity profile and to explore immunological biomarkers of the CD40-activating antibody CP-870,893 with cisplatin and pemetrexed in patients with malignant pleural mesothelioma (MPM).

PATIENTS AND METHODS

Eligible patients had confirmed MPM, ECOG performance status 0-1, and measurable disease. Patients received cisplatin 75 mg/m(2) and pemetrexed 500 mg/m(2) on day 1 and CP-870,893 on day 8 of a 21-day cycle for maximum 6 cycles with up to 6 subsequent cycles single-agent CP-870,893. Immune cell subset changes were examined weekly by flow cytometry.

RESULTS

Fifteen patients were treated at three dose levels. The MTD of CP-870,893 was 0.15 mg/kg, and was exceeded at 0.2 mg/kg with one grade 4 splenic infarction and one grade 3 confusion and hyponatraemia. Cytokine release syndrome (CRS) occurred in most patients (80%) following CP-870,893. Haematological toxicities were consistent with cisplatin and pemetrexed chemotherapy. Six partial responses (40%) and 9 stable disease (53%) as best response were observed. The median overall survival was 16.5 months; the median progression-free survival was 6.3 months. Three patients survived beyond 30 months. CD19+ B cells decreased over 6 cycles of chemoimmunotherapy (P < 0.001) with a concomitant increase in the proportion of CD27+ memory B cells (P < 0.001) and activated CD86+CD27+ memory B cells (P < 0.001), as an immunopharmacodynamic marker of CD40 activation.

CONCLUSIONS

CP-870,893 with cisplatin and pemetrexed is safe and tolerable at 0.15 mg/kg, although most patients experience CRS. While objective response rates are similar to chemotherapy alone, three patients achieved long-term survival.

AUSTRALIA NEW ZEALAND CLINICAL TRIALS REGISTRY NUMBER

ACTRN12609000294257.

Acinic cell carcinoma of the breast: review of the literature

INTRODUCTION

The breast and salivary gland tissue share embryologic and thus pathological similarities. Acinic cell carcinoma (ACC) is a typical tumor in salivary glands, but rarely arises in breast too. We reviewed 38 cases of mammary ACC reported in literature and our case, the first ACC born within a fibroadenoma.

MATERIALS AND METHODS

Data were collected by a research for the key words acinic cell carcinoma breast on Pubmed in March 2014, including a case treated in our department. All reviewed cases were compared for clinical approach and histological pattern.

RESULTS

To date 23 articles presenting cases of ACC of the breast are reported in literature. We included in our review 38 cases previously described and one new case. The histological pattern was predominantly solid with a microglandular structure. All the tumor cells were cytologically characterized by monotonous round cells with a finely granular, weakly eosinophilic, or clearly vacuolated cytoplasm. The most of the cells were intensely stained with anti-lysozime, anti-amylase, anti-α1-chimotripsin, anti-EMA and anti-S100 protein antisera. Immunohistochemistry was also performed to point out: estrogen receptor (ER), progesterone receptor (PR), androgen receptors (AR), human epidermal growth factor receptor 2 overexpression (HER2/neu), E-cadherin (E-cad), cytokeratin-7 (CK7), gross cystic disease fluid protein 15 (GCDFP15), smooth muscle actin (SMA).

CONCLUSION

ACC of the breast is a rare tumor, showing similarities with the salivary gland counterpart, above all in terms of good prognosis, and differences from the ordinary invasive breast carcinoma. Further investigations are needed to elucidate the true histogenesis and the correct treatment.

Positive findings in preoperative testing prior to gastric banding: their real value

AIM

Relations between laparoscopic adjustable gastric banding (LAGB), gastroesophageal reflux (GER) and hiatal hernia (HH) are controversial. In this context the role of preoperative investigations to assess upper gastrointestinal (GI) function and its impact on the approach to LAGB and outcomes remains unclear. The aim was to define the value of preoperative upper GI testing, and to relate the findings with postoperative outcomes.

METHODS

Seventy-eight cases were enrolled among 250 patients undergoing LAGB from January 2010 to December 2011 in our Center for the Multidisciplinary treatment of severe obesity. Patients were submitted preoperatively to endoscopy and radiologic series with oral contrast to assess the state of upper GI mucosa, the presence of HH, GER or cardias incontinence. According to the findings, patients were assigned to group A, if one or both exams showed positive results; or to the control group B if both exams were negative.

RESULTS

GI series showed GER in 14.1% of patients, HH in 6.4%, altered motility in 5.1%, gastritis in 3.1%and were negative in 75.6%. Endoscopy showed gastritis in 71.8%of patients, HH in 30.8%, esophagitis in 7.7%, duodenitis in 7.7%, LES incontinence in 8%; while only 21.8% of patients had a negative exam. Differences between group A and B are not statistically significant in terms of pre- and post-operative BMI, EBWL%, long-term complications, time and number of regulations.

CONCLUSION

Positive findings in preoperative testing rarely postpone or change the surgical approach and postoperative outcomes. Our results encourage the omission of upper GI series from routine evaluation protocol prior to LAGB.

Gastric emptying after sleeve gastrectomy: statistical evidence of a controlled prospective study with gastric scintigraphy

AIM

Laparoscopic sleeve gastrectomy (LSG) is a stand-alone bariatric procedure, its feasibility and efficacy being confirmed by long-term data. The effect of the procedure is believed to be based on the gastric restriction and reduction of ghrelin. Nevertheless it remains still controversial the role of LSG on gastric emptying and the impact that this may have on weight loss outcomes. Our aim is to assess gastric emptying after LSG using gastric scintigraphy.

METHODS

For this prospective randomized study, 45 patients undergoing LSG at our Centre for the Multidisciplinary Treatment of Severe Obesity from April 2009 to April 2011 were enrolled and observed prospectively (Group A). The inclusion criteria followed the guidelines for bariatric surgery. All patients performed gastric emptying scintigraphy through a standard semisolid meal (250 kcal), marked with 0.5 mCiTc 99. Group A performed the exam before (A1) and after the operation (A2). A control group (Group B) included 20 patients undergoing scintigraphic assessment for other reasons.

RESULTS

LSG was performed following a standardized technique. No complications were observed. The scintigraphic study showed a reduced half-life tracer (A1 vs. A2: 80.4±16.5 min vs. 64.3±22 min P=0.06), without a significant difference. Comparing the two groups no differences occurred before operation (B vs. A1). Gastric emptying time resulted significatively reduced in group A2 rather than in group A1 and B.

CONCLUSION

Gastric motility plays a role in the pathogenesis of obesity. Our experience suggests that LSG reduces gastric emptying time, but further studies are necessary to reach statystical significativity.

Molecular screening of virulence genes in high-level gentamicin-resistant Enterococcus faecalis and Enterococcus faecium isolated from clinical specimens in Northwest Iran

PURPOSE

The present study screened clinical isolates of Enterococcus faecalis and Enterococcus faecium to determine the prevalence of high-level gentamicin-resistant enterococci and the potential virulence genes among them.

MATERIALS AND METHODS

Clinical enterococcal isolates were obtained from three university teaching hospitals in Northwest Iran. Isolated enterococci were identified phenotypically followed by antibiotic susceptibility testing. Multiplex PCR was performed for the detection of genus, species-specific targets, gentamicin resistance, and potential virulence genes.

RESULTS

Of 220 enterococcal isolates, 133 (60.45%) isolates were identified as high-level gentamicin-resistant. Of these isolates, 79 (59.4%) and 54 (40.6%) were E. faecalis and E. faecium, respectively. All high-level gentamicin-resistant strains carried aac(6')Ie-aph(2″)Ia. Of 220 isolates, 65.9% were positive for gelE, and 55%, 53.6%, 51.8%, and 49.5% of isolates were positive for cpd, asa1, ace, and esp, respectively. Phenotypically detected β-haemolytic strains (19.54%) were found to possess cylL ls MAB.

CONCLUSION

The study revealed that high-level gentamicin-resistance was related to the presence of aac(6')Ie-aph(2″)Ia. Isolated enterococci harboured potential virulence determinants, which were more common among E. faecalis than among E. faecium strains.

Determining the accuracy of base deficit in diagnosis of intra-abdominal injury in patients with blunt abdominal trauma

BACKGROUND

Blunt abdominal trauma is a leading cause of morbidity and mortality among all age groups. A multiplicity of diagnostic modalities exists to evaluate the abdomen. We sought to assess the diagnostic performance of base deficit (BD) in identifying intra-abdominal injury in patients with blunt abdominal trauma.

METHODS

A prospective, nonrandomized series of patients with blunt abdominal trauma admitted into the 2 emergency departments was investigated from September 2007 to September 2008. Arterial blood samples were analyzed. According to BD, the patients were divided into 2 groups: group 1 who had a BD of -6 or lower and group 2 who had a BD more than -6. Ultrasonography, computed tomographic scan, or laparotomy was performed to find intra-abdominal injury. Follow-up at 7 days by telephone interview was obtained on patients who were discharged.

RESULTS

A total of 400 patients were enrolled, with a mean (SD) age of 34.8 ± 17.1 years. Two hundred sixty-eight (67%) of them were male. Seventy-six (19%) of patients had a BD of -6 or lower. Sixty-eight (17%) of them showed to have intra-abdominal injury with a BD of approximately -8.7 ± 3.2, compared with patients without intra-abdominal injury, -0.4 ± 0.1. Patients with a BD of -6 or lower achieved more laparotomy and blood transfusion compared with patients with a BD more than -6. On receiver operating characteristic curve analysis, the cutoff point of -6 was obtained with sensitivity and specificity of 88.2% and 95.2% and with positive and negative predictive values of 79% and 97.5%, respectively. None of outpatients had abdominal problem in telephone follow-up.

CONCLUSIONS

These data show that the BD is an early available important indicator to identify intra-abdominal injury in patients with blunt abdominal trauma, as well as a high transfusion requirement.

Domiciliary humidification improves lung mucociliary clearance in patients with bronchiectasis

Inspired air humidification has been reported to show some benefit in bronchiectatic patients. We have investigated the possibility that one effect might be to enhance mucociliary clearance. Such enhancement might, if it occurs, help to lessen the risks of recurrent infective episodes. Using a radioaerosol technique, we measured lung mucociliary clearance before and after 7 days of domiciliary humidification. Patients inhaled high flow saturated air at 37 degrees C via a patient-operated humidification nasal inhalation system for 3 h per day. We assessed tracheobronchial mucociliary clearance from the retention of (99m)Tc-labelled polystyrene tracer particles monitored for 6 h, with a follow-up 24-h reading. Ten out of 14 initially recruited patients (age 37-75 years; seven females) completed the study (two withdrew after their initial screening and two prior to the initial clearance test). Seven patients studied were non-smokers; three were ex-smokers (1-9 pack-years). Initial tracer radioaerosol distribution was closely similar between pre- and post-treatment. Following humidification, lung mucociliary clearance significantly improved, the area under the tracheobronchial retention curve decreased from 319 +/- 50 to 271 +/- 46%h (p < 0.07). Warm air humidification treatment improved lung mucociliary clearance in our bronchiectatic patients. Given this finding plus increasing laboratory and clinical interest in humidification mechanisms and effects, we believe further clinical trials of humidification therapy are desirable, coupled with analysis of humidification effects on mucus properties and transport.

Mucociliary clearance in COPD can be increased by both a D2/β2 and a standard β2 agonists

In addition to breathlessness and cough, excessive mucus production is one of the main symptoms of chronic obstructive pulmonary disease (COPD). Excess mucus coupled with deteriorating mucociliary clearance is associated with a decline in lung function and an increased risk of death from pulmonary infection. The effect of Viozan (Sibenadet HCl, AR-C68397AA), a novel dual D2 dopamine receptor, beta2-adrenoceptor agonist, on mucociliary clearance was investigated together with that of a beta2-adrenoceptor agonist, salbutamol. Using a double blind, parallel group study design, 15 patients with COPD, all habitual smokers, were randomised to receive nebulised sidenadet (3mg tid; n = 7) or salbutamol (5mg tid; n = 8) for 10 days. Lung mucociliary clearance rates were measured, by a standard radioaerosol technique, before and after the treatment period, as were 24-h sputum volumes. Both sibenadet and salbutamol therapies resulted in significant (P<0.02) enhancement of lung mucociliary clearance. The 24-h sputum volume was significantly reduced following sibenadet therapy (P<0.03) whereas salbutamol therapy had no effect. Our results, in addition to illustrating the effects of a standard beta2 agonist on mucociliary clearance, strongly suggest the potential dual benefit of dual-agonist compounds in lessening sputum production whilst simultaneously enhancing mucociliary clearance. For reasons unconnected with the present study, development work on this specific formulation is no Longer proceeding.

Effect of salmeterol xinafoate on lung mucociliary clearance in patients with asthma

Lung mucociliary clearance is impaired in stable asthma. The long-acting beta2-agonist salmeterol has been shown in vitro to cause a significant increase in ciliary beat frequency. It seemed possible therefore that salmeterol may also have a favourable effect on lung mucociliary transport in asthmatic patients. Fourteen patients with asthma participated in a double-blind, placebo-controlled, crossover study to assess the effect of 2 weeks of treatment with salmeterol MDI (50 microg b.d.) on lung mucociliary clearance. The 11 patients who completed the study (seven males, four females) had a mean +/- SE age of 50 +/- 4 years, % predicted FEV1 of 74 +/- 8% and a tobacco consumption history of 13 +/- 7 pack-years (seven non-smokers, four exsmokers). Lung mucociliary transport was measured by a radioaerosol technique. Pulmonary function indices (FEV1, FVC, and PEF) were significantly improved on salmeterol relative to placebo. The main radioaerosol finding was a significant increase in the penetration of radioaerosol into the lung with 24-h radioaerosol rising from 40 +/- 5% on placebo to 49 +/- 4% (P < 0.01) on salmeterol. Despite this increased penetration, a slight favourable change occurred in tracheobronchial aerosol clearance. This study demonstrates that 2 weeks salmeterol treatment influences deposition of particles within the lung by increasing airway patency and indicates a beneficial effect of MDI salmeterol on lung mucociliary clearance.

Effect of oral antibiotics on lung mucociliary clearance during exacerbation of chronic obstructive pulmonary disease

It has been well established that lung mucociliary clearance is depressed in patients with chronic obstructive pulmonary disease. This study examines whether oral antibiotics have a detectable effect on this clearance mechanism during exacerbation in patients with such disease. Twelve patients with a mean +/- SE age of 63 +/- 2 years participated in a randomized, double-blind, parallel group study to assess the effect of 1 week of treatment with amoxycillin (500 mg t.d.s.) or ciprofloxacin (500 mg b.d.) on lung mucociliary clearance during exacerbation. Lung mucociliary clearance rates were measured by a non-invasive radioaerosol technique. Both drugs on average resulted in small, non-significant, enhancement of mucociliary clearance. Following treatment, the numbers of coughs were reduced in both groups and significantly (P < 0.05) after treatment with ciprofloxacin. Sputum production was also significantly reduced (P < 0.01) in both groups. The magnitude of improvement in lung mucociliary clearance was relatively modest following 1 week of treatment with either antibiotic. Since the number of coughs was significantly less after ciprofloxacin treatment the measured enhancement of lung mucociliary transport is probably, however, an underestimate.

Opposite effects of inhaled bradykinin and [desArg9]-bradykinin on tracheobronchial clearance in normal humans

Kinins may affect lung mucociliary clearance in man by interacting with specific surface receptors designated B1 and B2. To evaluate this possibility, we have compared the effect of inhaled bradykinin and [desArg9]-bradykinin on mucociliary clearance in healthy volunteers. Four subjects attended the laboratory on three separate occasions to undertake tracheobronchial clearance studies, by a noninvasive radioisotopic technique, followed by inhalation with either bradykinin (8 mg.mL-1), [desArg9]-bradykinin (8 mg.mL-1), or vehicle placebo 30 min after radioaerosol inhalation. Half-hourly whole lung counts were measured for 6 h with two collimated scintillation counters and a tracheobronchial clearance curve was plotted for each subject on each occasion. In all the subjects studied, mucociliary clearance, expressed as the area under the tracheobronchial radioaerosol retention curve calculated for the first 6 h (AUCo-6h) was enhanced after inhaling bradykinin and prolonged following exposure with [desArg9]-bradykinin when compared to placebo. The median values (range) for AUCo-6h were significantly reduced from 123 (83-152)%.h to 92 (51-133)%.h with placebo and bradykinin, respectively, and significantly augmented to 269 (144-331)%.h after exposure with [desArg9]-bradykinin. This small study suggests that acute exposure with inhaled bradykinin accelerates, whilst [desArg9]-bradykinin delays, tracheobronchial clearance in normal human airways.

No effect of gender on lung mucociliary clearance in young healthy adults

Lung mucociliary clearance (LMC) depends on age and it is adversely affected by cigarette smoking. When using the radioaerosol technique for measuring LMC the initial site of deposition of the radioaerosol within the lungs affects its rate of removal. Whether there is a difference in gender for LMC is still an open question. Forty-one (20 female, 21 male) healthy, non-smoking subjects had their lung mucociliary clearance measured using an objective, non-invasive radioaerosol technique. The male and female groups were closely matched for initial distribution of the radioaerosol. There was no statistical significant difference between males and females in the rate of clearance of inhaled radioaerosol over a 6 h observation period. When comparing the LMC of two groups although it is important to match them for age, smoking habits and initial topographical distribution of the tracer radioaerosol it does not seem essential to also match the two groups for gender.

Inhaled frusemide does not affect lung mucociliary clearance in healthy and asthmatic subjects

Inhaled frusemide has been shown to protect against the bronchoconstrictor effect of several inhaled agents in asthmatic subjects by mechanism(s) that are unclear. Since loop diuretics can modulate Cl- transport in the airway epithelium, frusemide may alter the quality and/or the quantity of the periciliary layer, which in turn may affect lung mucociliary transport. We investigated the effect of a single inhalation of nebulized frusemide (40 mg) on lung mucociliary clearance in four healthy subjects and in seven stable, mild asthmatics using an objective radioaerosol technique. Frusemide or placebo was inhaled in a double-blind, randomized, cross-over manner half an hour after the inhalation of 5 microns polystyrene particles labelled with 99mTc, used for assessing mucociliary clearance. The pulmonary function and initial radioaerosol distribution were similar between frusemide and placebo runs within each of the two study groups. The areas under the tracheobronchial retention curves over the 6 h observation period were similar between frusemide and placebo runs for both groups. Our findings show inhaled frusemide, at a dose known to inhibit bronchoconstrictor responses, does not affect lung mucociliary clearance.

Regional lung clearance during cough and forced expiration technique (FET): effects of flow and viscoelasticity

BACKGROUND

In vitro studies have suggested that both the viscoelastic properties of lung secretions and the peak flow attained during simulated cough influence clearance. This study examines the possible association of the viscoelastic properties of sputum and maximum expiratory flow with measured effectiveness of mucus clearance induced by instructed cough and by forced expiration technique (FET) in patients with airways obstruction.

METHODS

Nineteen patients (11 men and eight women) of mean (SE) age, % predicted FEV1, and daily sputum wet weight of 64 (2) years, 52 (6)%, and 37.5 (7.9) g respectively participated in the study. Mucus movement from proximal and peripheral lung regions was measured by an objective non-invasive radioaerosol technique. Each patient underwent three assessments: control, cough, and FET. During cough and FET, maximum expiratory flow was measured at the mouth level. Apparent viscosity and elasticity of the expectorated sputum samples were measured with a viscometer.

RESULTS

Compared with the control run (mean (SE) clearance: 16 (3)%) there was an increase in clearance from the whole lung during cough (44 (5)%) and FET (42 (5)%), and also an enhanced clearance of inhaled, deposited radioaerosol from the trachea, inner and intermediate regions of the lungs, but not from the outer region. There were, however, no differences in regional clearance between cough and FET. Neither regional nor total clearance correlated with maximum expiratory flow, apparent viscosity, elasticity, or daily sputum wet weight.

CONCLUSIONS

These results confirm that cough and FET both promote effective clearance but suggest that, unlike in vitro studies, sputum production and viscoelasticity, as well as maximum expiratory flow, provide no guide to clearance efficacy in humans.

Regional mucus transport following unproductive cough and forced expiration technique in patients with airways obstruction

It has previously been shown that unproductive coughing in both healthy subjects and patients with airways obstruction is not effective in clearing lung secretions. This study investigates the regional mucus transport in a group of subjects with airways obstruction who failed to expectorate following instructed cough and forced expiration technique. Fourteen patients (mean +/- SEM age: 68 +/- 2 years) with airways obstruction (mean +/- SEM percent predicted. FEV1: 54 +/- 5; daily wet weight sputum: 9.1 +/- 2.0 g) took part in the study which was a randomized, three-way crossover within-patient design. Each patient underwent three treatment maneuvers: control, cough (30 coughs over a 10-min period), and forced expiration (30 forced expirations over a 10-min period). An objective radioaerosol technique was used to monitor regional mucus movement within the lungs of the patients. The lungs were divided arbitrarily into four regions of interest: tracheal, inner, intermediate, and outer. Peak expiratory flow rate during cough and forced expiration was measured at the mouth. There was no correlation between the radioaerosol clearance from all regions and (1) mean peak flow during cough and forced expiration, and (2) mean 24-h sputum production prior to the study day. There were no differences in regional radioaerosol clearance between cough and forced expiration. However, both cough and forced expiration resulted in significant clearance compared with control for all regions with the exception of the forced expiration in the outer region. To our knowledge, this study is the first to demonstrate that unproductive cough and forced expiration result in movement of secretions proximally from all regions of the lung in patients with airways obstruction.

No added benefit from nebulized amiloride in patients with cystic fibrosis

In cystic fibrosis (CF) airway epithelial sodium absorption is increased 2-3 fold. Since sodium absorption is inhibited by the sodium channel blocker amiloride, our aim was to assess its therapeutic benefit in cystic fibrosis. A randomized, double-blind, placebo-controlled, cross-over trial of nebulized amiloride was performed in 23 patients with cystic fibrosis. Amiloride or placebo was administered four times daily for two six month periods. Existing treatment was continued, and any infective exacerbations treated in the usual way. Fourteen patients completed the study. No significant changes occurred in forced expiratory volume in one second, forced vital capacity, oxygen saturation, body weight, sputum volume, culture and rheology, serum urea, and electrolytes, white cell count and erythrocyte sedimentation rate during either treatment period. The frequency of infective exacerbations was also not different in either treatment period. We were thus unable to confirm the benefit shown in the only other clinical trial of nebulized amiloride in cystic fibrosis and conclude that, in the presence of established treatment for cystic fibrosis lung disease, nebulized amiloride offers no additional clinical benefit.

No added benefit from nebulized amiloride in patients with cystic fibrosis

In cystic fibrosis (CF) airway epithelial sodium absorption is increased 2-3 fold. Since sodium absorption is inhibited by the sodium channel blocker amiloride, our aim was to assess its therapeutic benefit in cystic fibrosis. A randomized, double-blind, placebo-controlled, cross-over trial of nebulized amiloride was performed in 23 patients with cystic fibrosis. Amiloride or placebo was administered four times daily for two six month periods. Existing treatment was continued, and any infective exacerbations treated in the usual way. Fourteen patients completed the study. No significant changes occurred in forced expiratory volume in one second, forced vital capacity, oxygen saturation, body weight, sputum volume, culture and rheology, serum urea, and electrolytes, white cell count and erythrocyte sedimentation rate during either treatment period. The frequency of infective exacerbations was also not different in either treatment period. We were thus unable to confirm the benefit shown in the only other clinical trial of nebulized amiloride in cystic fibrosis and conclude that, in the presence of established treatment for cystic fibrosis lung disease, nebulized amiloride offers no additional clinical benefit.

Effect of oral bronchodilators on lung mucociliary clearance during sleep in patients with asthma

BACKGROUND

Lung mucociliary clearance rates are reduced during sleep in patients with asthma. Methylxanthines and beta 2 agonists have been shown to enhance rates of lung mucociliary clearance. This study examined whether oral slow release bronchodilators may also have an effect on this clearance mechanism during sleep in patients with asthma.

METHODS

Nine patients with asthma with a mean(SE) age of 65(5) years and percentage predicted forced expiratory volume in one second (FEV1 of 61(9)% participated in a double blind, placebo controlled, within subject crossover study to assess the effect of two weeks of treatment with salbutamol (Volmax; 8 mg twice daily) or theophylline (Phyllocontin; 350 mg twice daily) on lung mucociliary clearance during sleep. Lung mucociliary clearance rates were measured by a radioaerosol technique.

RESULTS

The observation period for radioaerosol clearance was approximately 0.3 hours before sleep, 6.0 hours during sleep and 0.6 hours after sleep. Mean mucociliary clearance rates for theophylline, placebo and salbutamol before sleep were: 39, 39, and 32%/hour respectively; during sleep: 11, 10, and 9%/hour respectively; and after sleep: 39, 32, and 35%/hour respectively.

CONCLUSION

During sleep lung mucociliary clearance in stable asthma was reduced, which is in agreement with the group's previous findings. Treatment with controlled/slow release oral bronchodilators had no effect on this reduced rate of clearance associated with sleep.

Acute effect of inhaled bradykinin on tracheobronchial clearance in normal humans

BACKGROUND

Bradykinin, a nonapeptide that contributes as a mediator to the pathogenesis of asthma, may affect lung mucociliary clearance, as it has been shown to be a potent secretagogue in canine airways and in human nasal mucosa in vivo. To evaluate this possibility the effect of inhaled bradykinin on mucociliary clearance has been studied in 10 healthy volunteers.

METHODS

Subjects attended the laboratory on two occasions to take part in tracheobronchial clearance studies using a non-invasive radioisotopic technique. Inhalation of radioaerosol was followed 30 minutes later by inhalation of either bradykinin (8 mg/ml) or vehicle placebo in a randomised, double blind fashion. After each inhalation the number of coughs was recorded. Whole lung radioactivity was measured every half hour for six hours with two collimated scintillation counters, and a tracheobronchial clearance curve was plotted for each subject on each occasion.

RESULTS

Mucociliary clearance, expressed as the area under the tracheobronchial radioaerosol retention curve calculated for the first six hours (AUC0-6h), was greater in nine out of 10 subjects after inhalation of bradykinin than after placebo. The median values (range) for AUC0-6h were significantly reduced from 126% (78-232%)/h with placebo to 87% (51-133%)/h with bradykinin.

CONCLUSION

It is concluded that acute exposure to inhaled bradykinin accelerates tracheobronchial clearance in normal human airways.

[The modulator effect of bradykinin with respect to tracheobronchial clearance in healthy subjects]

Bradykinin (Bk), a vasoactive nonapeptide which has been proposed as mediator in the pathogenesis of bronchial asthma, is a potent secretagogue in canine airways and in human nasal mucosa in vivo. A study was carried out in order to evaluate the effect of inhaled Bk on tracheobronchial clearance (TBC), measured by a radioaerosol technique in 10 healthy volunteers. Subjects inhaled Bk (8 mg/mL) or vehicle placebo on two occasions, at least 2 weeks apart, in a double blind and randomized fashion 30 min after radioaerosol inhalation. TBC, expressed as the area under the tracheobronchial radioaerosol retention curve calculated for the first 6 hours (AUC 0-6h), was enhanced in 9 of 10 subjects following inhaled Bk when compared to placebo. The mean values for AUC 0-6h were significantly reduced from 132%.h to 92%.h (p < 0.001) with placebo and Bk respectively. We conclude that Bk has a marked effect on tracheobronchial clearance in normal human airways.

Impairment of lung mucociliary clearance in pigeon fanciers

Lung mucociliary clearance was measured in 15 pigeon fanciers. The study group was subdivided into two: a precipitin-positive group (n = 10; mean +/- SEM age 45 +/- 5 years) with circulating blood precipitins and a precipitin-negative group (n = 5; mean +/- SEM age 40 +/- 3 years) without. Clearance was measured using an objective, noninvasive radioaerosol technique. The data for both groups were compared with those of matched control groups of healthy subjects. The mean +/- SEM area under the tracheobronchial retention curves (AUC) over the 6-h observation period was 257 +/- 27 %h for the precipitin-positive group compared with 177 +/- 16 %h for its control group (p = 0.02)--a high AUC value denoting slow clearance. That for the precipitin-negative group was 282 +/- 34 %h compared with 150 +/- 15 %h for its control group (p = 0.02). Our study illustrates in pigeon fanciers involvement of the conducting airways in that a major defense mechanism of the airways--namely, mucociliary clearance--is substantially compromised. The presence or absence of precipitins appears not to be related to the degree of mucociliary clearance impairment.

Tracheobronchial clearance in patients with pulmonary sarcoidosis

Lung mucociliary clearance was measured using an objective, noninvasive radioaerosol technique in 13 patients with pulmonary sarcoidosis and 13 matched, healthy control subjects. Four of the sarcoid patients had never received any steroid therapy, five were currently receiving oral corticosteroids, and the remaining four were using inhaled corticosteroids only. A statistically significant retardation in tracheobronchial clearance (p less than 0.02) was observed in the sarcoid patients compared to the control subjects. The sarcoid patients using inhaled corticosteroids appeared to demonstrate the greatest degree of mucociliary transport impairment. The sarcoid patients in apparent remission and those receiving oral corticosteroid therapy had clearances better than those using inhaled corticosteroids, but they were still reduced compared to the control subjects. This study demonstrates that lung mucociliary clearance is adversely affected in patients with pulmonary sarcoidosis and raises the question of the possible consequences that could follow long-term inhaled immunosuppressive therapy on the prime clearance defense mechanism within the human lungs.

Effect of temazepam on tracheobronchial mucus clearance

BACKGROUND

Tracheobronchial clearance of mucus from the lungs is reduced during sleep and, usually, by the administration of opiates. It seemed possible therefore that temazepam, a widely used potent benzodiazepine, retarded clearance.

METHODS

The effect of 10 mg temazepam on mucociliary clearance was studied in eight healthy volunteers, aged 18-50 (mean 30) years, in a randomised, placebo controlled, double blind, cross-over study. Six subjects were female and two male. Six were non-smokers and two were light current smokers. Clearance was assessed from the change in radio-activity in the lungs after inhalation of 5 microns diameter polystyrene particles, labelled with technetium-99m, under controlled conditions.

RESULTS

Tracheobronchial clearance was reduced by 22% after temazepam by comparison with placebo during the first three hours after drug ingestion; this is the period when circulating drug concentrations are highest.

CONCLUSION

Temazepam should be prescribed with caution in patients with impaired lung mucociliary transport.

Effect of inhaled 15-(s)-hydroxyeicosatetraenoic acid on tracheobronchial clearance in normal human airways

15-(s)-Hydroxyeicosatetraenoic acid (15-HETE) is the predominant metabolite of arachidonic acid in normal and asthmatic human airways and a potent mucus secretagogue in canine and human airways. A study was carried out on the effect of inhaled 15-HETE on tracheobronchial clearance, measured for six hours by a radioaerosol technique, in 10 normal subjects. Subjects inhaled 80 nmol 15-HETE or the diluent (sodium phosphate buffer) on two occasions at least two weeks apart in a double blind and randomised fashion (20 minutes after radioaerosol inhalation. Tracheobronchial clearance after inhaled 15-HETE was almost identical to that after placebo for all measurements up to six hours. It is concluded that 15-HETE has no effect on tracheobronchial clearance in normal human airways and is unlikely to account for the impaired mucociliary clearance seen in asthma.

The effect of unproductive coughing/FET on regional mucus movement in the human lungs

The study was designed to ascertain the movement of mucus from proximal and peripheral regions within the human lungs during cough and the forced expiration technique (FET). Mucus movement was measured using a radioaerosol technique. Seven patients (mean +/- SEM age: 63 +/- 3 years) with airways obstruction (% predicted FEV1: 44 +/- 4) participated in the study. Each patient underwent three assessments in a randomized manner: control/cough/FET. Peak expiratory flow rate (PEFR) was measured at the mouth during cough and FET. None of the patients produced sputum during the assessment periods. Both cough and FET compared with control increased, on average, mucus clearance from all regions; statistical significance was achieved only for central lung regions with cough (P less than 0.05). There was no significant correlation between PEFR during cough/FET and regional lung clearance.