Bronchial dentures as a cause of airway actinomycosis

A 65-year-old man was referred to the respiratory clinic with recurrent chest infections on a background of stage 3 chronic obstructive pulmonary disease. On examination, there was wheeze bilaterally more marked on the left lower lobe. Subsequent imaging revealed an obstruction of the left main bronchus that was concerning for malignancy. Initially, on flexible bronchoscopy, a hard mass was found and multiple biopsies were positive for actinomycosis. Subsequent rigid bronchoscopy was undertaken and a set of dentures were removed from the airway.

Cystic fibrosis transmembrane conductance regulator intracellular processing, trafficking, and opportunities for mutation-specific treatment

Recent advances in basic science have greatly expanded our understanding of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR), the chloride and bicarbonate channel that is encoded by the gene, which is mutated in patients with CF. We review the structure, function, biosynthetic processing, and intracellular trafficking of CFTR and discuss the five classes of mutations and their impact on the CF phenotype. The therapeutic discussion is focused on the significant progress toward CFTR mutation-specific therapies. We review the results of encouraging clinical trials examining orally administered therapeutics, including agents that promote read-through of class I mutations (premature termination codons); correctors, which overcome the CFTR misfolding that characterizes the common class II mutation F508del; and potentiators, which enhance the function of class III or IV mutated CFTR at the plasma membrane. Long-term outcomes from successful mutation-specific treatments could finally answer the question that has been lingering since and even before the CFTR gene discovery: Will therapies that specifically restore CFTR-mediated chloride secretion slow or arrest the deleterious cascade of events leading to chronic infection, bronchiectasis, and end-stage lung disease?

The ΔF508 mutation causes CFTR misprocessing and cystic fibrosis-like disease in pigs

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. The most common CF-associated mutation is ΔF508, which deletes a phenylalanine in position 508. In vitro studies indicate that the resultant protein, CFTR-ΔF508, is misprocessed, although the in vivo consequences of this mutation remain uncertain. To better understand the effects of the ΔF508 mutation in vivo, we produced CFTR(ΔF508/ΔF508) pigs. Our biochemical, immunocytochemical, and electrophysiological data on CFTR-ΔF508 in newborn pigs paralleled in vitro predictions. They also indicated that CFTR(ΔF508/ΔF508) airway epithelia retain a small residual CFTR conductance, with maximal stimulation producing ~6% of wild-type function. Cyclic adenosine 3',5'-monophosphate (cAMP) agonists were less potent at stimulating current in CFTR(Δ)(F508/)(Δ)(F508) epithelia, suggesting that quantitative tests of maximal anion current may overestimate transport under physiological conditions. Despite residual CFTR function, four older CFTR(ΔF508/ΔF508) pigs developed lung disease similar to human CF. These results suggest that this limited CFTR activity is insufficient to prevent lung or gastrointestinal disease in CF pigs. These data also suggest that studies of recombinant CFTR-ΔF508 misprocessing predict in vivo behavior, which validates its use in biochemical and drug discovery experiments. These findings help elucidate the molecular pathogenesis of the common CF mutation and will guide strategies for developing new therapeutics.

Cystic fibrosis pigs develop lung disease and exhibit defective bacterial eradication at birth

Lung disease causes most of the morbidity and mortality in cystic fibrosis (CF). Understanding the pathogenesis of this disease has been hindered, however, by the lack of an animal model with characteristic features of CF. To overcome this problem, we recently generated pigs with mutated CFTR genes. We now report that, within months of birth, CF pigs spontaneously developed hallmark features of CF lung disease, including airway inflammation, remodeling, mucus accumulation, and infection. Their lungs contained multiple bacterial species, suggesting that the lungs of CF pigs have a host defense defect against a wide spectrum of bacteria. In humans, the temporal and causal relations between inflammation and infection have remained uncertain. To investigate these processes, we studied newborn pigs. Their lungs showed no inflammation but were less often sterile than controls. Moreover, after introduction of bacteria into their lungs, pigs with CF failed to eradicate bacteria as effectively as wild-type pigs. These results suggest that impaired bacterial elimination is the pathogenic event that initiates a cascade of inflammation and pathology in CF lungs. Our finding that pigs with CF have a host defense defect against bacteria within hours of birth provides an opportunity to further investigate CF pathogenesis and to test therapeutic and preventive strategies that could be deployed before secondary consequences develop.

Disruption of the CFTR gene produces a model of cystic fibrosis in newborn pigs

Almost two decades after CFTR was identified as the gene responsible for cystic fibrosis (CF), we still lack answers to many questions about the pathogenesis of the disease, and it remains incurable. Mice with a disrupted CFTR gene have greatly facilitated CF studies, but the mutant mice do not develop the characteristic manifestations of human CF, including abnormalities of the pancreas, lung, intestine, liver, and other organs. Because pigs share many anatomical and physiological features with humans, we generated pigs with a targeted disruption of both CFTR alleles. Newborn pigs lacking CFTR exhibited defective chloride transport and developed meconium ileus, exocrine pancreatic destruction, and focal biliary cirrhosis, replicating abnormalities seen in newborn humans with CF. The pig model may provide opportunities to address persistent questions about CF pathogenesis and accelerate discovery of strategies for prevention and treatment.

Fractured closed suction catheter: an unusual cause of endobronchial obstruction in a ventilated patient

BACKGROUND

A 32-year-old HIV-positive man required ventilation for seizures secondary to viral encephalitis. He had a prolonged care unit stay and had percutaneous tracheostomy performed on day 14 of his admission. He subsequently developed persistent right basal infiltrates and atelectasis on chest radiographs that were slow to respond to antibiotic treatment. Fiberoptic bronchoscopy revealed the cause of his infiltrates to be a 14-cm tip section of closed suction catheter tubing that had presumably fractured during suctioning and became lodged in his trachea and right main bronchus.

LEARNING POINT

Foreign body aspiration should be considered in the differential diagnosis of persisting lung infiltrates or atelectasis in all patients.

CONCLUSION

This case describes a rare cause of endobronchial obstruction in a ventilated patient. Medical staff requires education about the importance of ensuring that suction catheters and other airway adjuncts are intact following use to prevent possible airway foreign bodies.

Fatal miliary Coccidioidomycosis in a patient receiving infliximab therapy: a case report

A 78-year-old white male from Iowa in the United States of America receiving the anti- tumor necrois factor (TNF) agent infliximab therapy for rheumatoid arthritis developed a cheek ulcer which failed to respond to empiric antibiotic therapy. He subsequently presented with progressive respiratory failure from miliary coccidioidomycosis which proved fatal. The patient vacationed in Arizona 6 months previously and likely contracted the organism there as Iowa is not an endemic area for coccidioidomycosis. Respiratory failure from miliary infiltration is an uncommon presentation of coccidioidomycosis. Physicians should be aware of the importance of travel history and potential for life-threatening coccidioidomycosis in patients receiving tumor necrosis factor inhibitors.

Neutrophil Elastase Up-Regulates Cathepsin B and Matrix Metalloprotease-2 Expression

Neutrophil elastase (NE) activity is increased in many diseases. Other families of proteases, including cathepsins and matrix metalloproteases (MMPs), are also present at elevated levels in similar disease conditions. We postulated that NE could induce expression of cathepsins and MMPs in human macrophages. NE exposure resulted in macrophages, producing significantly greater amounts of cathepsin B and latent and active MMP-2. Cathepsin B and MMP-2 activities were decreased in Pseudomonas-infected NE knockout mice compared with wild-type littermates. We also demonstrate that NE can activate NF-kappaB in macrophages, and inhibition of NF-kappaB resulted in a reduction of NE-induced cathepsin B and MMP-2. Also, inhibition of TLR-4 or transfection of macrophages with dominant-negative IL-1R-associated kinase-1 resulted in a reduction of NE-induced cathepsin B and MMP-2. This study describes for the first time a novel hierarchy among proteases whereby a serine protease up-regulates expression of MMPs and cathepsins. This has important implications for therapeutic intervention in protease-mediated diseases.

Migraine with aura following atrial septostomy for pulmonary arterial hypertension

BACKGROUND

A 34-year-old woman with known familial pulmonary arterial hypertension presented with syncope. Despite medical therapy with an endothelin-receptor antagonist and a phosphodiesterase inhibitor, the patient had NYHA class III symptoms, with exertional dyspnea. Right heart catheterization revealed severe pulmonary hypertension (right atrial pressure 15 mmHg, right ventricular pressure 80/15 mmHg, pulmonary artery pressure 80/35 mmHg, mean pulmonary artery pressure 52 mmHg). The patient underwent balloon atrial septostomy, creating a right-to-left shunt. Although she had no history of headaches or migraine attacks, the patient developed a migraine headache with aura on the third day after the procedure. Migraine attacks recurred for the next 2 days, but symptoms were relieved with simple analgesia.

INVESTIGATIONS

Physical examination, electrocardiography, laboratory testing, 6-min-walk test, right heart catheterization, chest radiography, transesophageal echocardiography, transthoracic echocardiography.

DIAGNOSIS

Migraine with aura following atrial septostomy.

MANAGEMENT

Bosentan, sildenafil, furosemide, spironolactone and warfarin therapy, atrial septostomy, and paracetamol therapy for migraine.

Antimicrobial proteins and polypeptides in pulmonary innate defence

Inspired air contains a myriad of potential pathogens, pollutants and inflammatory stimuli. In the normal lung, these pathogens are rarely problematic. This is because the epithelial lining fluid in the lung is rich in many innate immunity proteins and peptides that provide a powerful anti-microbial screen. These defensive proteins have anti-bacterial, anti- viral and in some cases, even anti-fungal properties. Their antimicrobial effects are as diverse as inhibition of biofilm formation and prevention of viral replication. The innate immunity proteins and peptides also play key immunomodulatory roles. They are involved in many key processes such as opsonisation facilitating phagocytosis of bacteria and viruses by macrophages and monocytes. They act as important mediators in inflammatory pathways and are capable of binding bacterial endotoxins and CPG motifs. They can also influence expression of adhesion molecules as well as acting as powerful anti-oxidants and anti-proteases. Exciting new antimicrobial and immunomodulatory functions are being elucidated for existing proteins that were previously thought to be of lesser importance. The potential therapeutic applications of these proteins and peptides in combating infection and preventing inflammation are the subject of ongoing research that holds much promise for the future.

Loss of Microbicidal Activity and Increased Formation of Biofilm Due to Decreased Lactoferrin Activity in Patients with Cystic Fibrosis

Intractable formation of biofilm by and infection with the opportunistic pathogen Pseudomonas aeruginosa are hallmarks of cystic fibrosis (CF). Lactoferrin, an innate immunity protein, has recently been shown to inhibit the formation of P. aeruginosa biofilm. Partial cleavage of lactoferrin by the proteases neutrophil elastase and Pseudomonas elastase has previously been described in CF. Here, we show that cathepsins in CF secretions are responsible for complete and rapid cleavage of lactoferrin. We demonstrate that levels of lactoferrin in P. aeruginosa-positive sputum samples are decreased when corrected for inflammatory burden and that P. aeruginosa-positive sputum samples have significantly higher cathepsin activity and significantly reduced ability to inhibit formation of biofilm, compared with P. aeruginosa-negative sputum samples. We also show that cleavage of lactoferrin by cathepsin results in loss of both its microbicidal and antibiofilm activity. Loss of such a vital innate immunity protein clearly has important implications for the pathogenesis of chronic P. aeruginosa lung infection in patients with CF.

Therapy for pharyngitis and tonsillitis caused by group A beta-hemolytic streptococci: a meta-analysis comparing the efficacy and safety of cefadroxil monohydrate versus oral penicillin V

A meta-analysis was conducted to compare the efficacy and safety of oral cefadroxil monohydrate (30 mg/kg QD or 15 mg/kg BID) with that of oral penicillin V (8, 10, or 15 mg/kg BID, TID, or QID) in the treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis and tonsillitis treated for 10 days. A simple random effects model was used for combining the efficacy and safety results of nine comparative trials performed in the United States. A total of 1646 patients aged < or = 19 years were considered evaluable; 1406 patients were evaluable using revised bacteriologic criteria, and 1499 patients were considered fully evaluable for safety. The results demonstrate significantly better response rates (P < 0.05) with cefadroxil monohydrate than with penicillin V for overall cure (91.8% versus 81.3%), bacteriologic cure (92.6% versus 81.4%), and bacteriologic recurrence (4.2% versus 10.5%); clinical cure rates were statistically similar (90.5% versus 90.2%). Revised bacteriologic criteria analysis revealed bacteriologic cure rates of 95.8% versus 88.7% (P < 0.05) and bacteriologic recurrence rates of 4.9% versus 7.1% (P = NS) for cefadroxil monohydrate and penicillin V, respectively. Adverse events related to drug administration occurred infrequently and did not differ significantly between treatment groups (P > 0.05). Compliance with cefadroxil monohydrate was at least as good as with penicillin V. Penicillin is currently the drug of choice in the treatment of GABHS pharyngitis and tonsillitis. Based on the information described in this large meta-analysis, cefadroxil monohydrate is an excellent alternative to oral penicillin V in the treatment of GABHS pharyngitis and tonsillitis.

Drug dispensing by physicians: promoter's claims examined

Experience in private pediatric practice is used to illustrate some potential advantages and disadvantages to patients and physicians of drug dispensing by physicians. Projections were based on the prescribing trends in the practice, the extent of patients' insurance reimbursement for prescriptions, the laws regarding dispensing, and the costs incurred when physicians purchase selected medications from a repackager or when patients procure them at a community pharmacy. Patients without insurance for prescriptions can potentially save money by purchasing medication at the physician's office but, in general, only if the physician's dispensing fee is minimal. Potential profits to physicians would be cut by an estimated 50% because of third-party enrollees choosing to have prescriptions filled at a pharmacy because of cost savings. Net profits are further reduced and may even be eliminated when the cost of physician and staff time to prepare, label, reorder, and maintain necessary records regarding dispensed medication are considered. Although it may be convenient for the patient to obtain initial supplies of medication at the time of an office visit, obtaining refills may be less convenient. The time and paperwork involved in dispensing by a physician cannot be considered as minimal interruptions in normal office procedure. The broad, attractive claims made in support of physician dispensing by physicians clearly overstate the benefits both to patients and to physicians.