Repeat administration of an adenovirus vector encoding cystic fibrosis transmembrane conductance regulator to the nasal epithelium of patients with cystic fibrosis

Cystic fibrosis (CF) is a common autosomal recessive disease caused by mutations in the CF transmembrane conductance regulator gene. Recombinant adenoviruses have shown promise as vectors for transfer of CF transmembrane conductance regulator cDNA to airway epithelia and correction of the Cl- transport defect. However, because adenovirus-mediated gene transfer is transient, use of adenovirus as a vector for treatment of CF would require repeated administration. Therefore, we evaluated repeat administration of an adenovirus vector to the nasal epithelium of patients with CF with five escalating doses of up to 10(10) infectious units. There were no detectable adverse affects. All subjects were initially seropositive but developed additional humoral immune responses. The vector partially corrected the defect in airway epithelial Cl- transport in some subjects, although there was variability between subjects and there was less correction with subsequent administration, perhaps because the immune response limited gene transfer. Future work must focus on vectors with increased efficiency and with the ability to evade host defenses.

Effect of aerosolized recombinant human DNase on exacerbations of respiratory symptoms and on pulmonary function in patients with cystic fibrosis. The Pulmozyme Study Group

BACKGROUND

Respiratory disease in patients with cystic fibrosis is characterized by airway obstruction caused by the accumulation of thick, purulent secretions, which results in recurrent, symptomatic exacerbations. The viscoelasticity of the secretions can be reduced in vitro by recombinant human deoxyribonuclease I (rhDNase), a bioengineered copy of the human enzyme.

METHODS

We performed a randomized, double-blind, placebo-controlled study to determine the effects of once-daily and twice-daily administration of rhDNase on exacerbations of respiratory symptoms requiring parenteral antibiotics and on pulmonary function. A total of 968 adults and children with cystic fibrosis were treated for 24 weeks as outpatients.

RESULTS

One or more exacerbations occurred in 27 percent of the patients given placebo, 22 percent of those treated with rhDNase once daily, and 19 percent of those treated with rhDNase twice daily. As compared with placebo, the administration of rhDNase once daily and twice daily reduced the age-adjusted risk of respiratory exacerbations by 28 percent (P = 0.04) and 37 percent (P < 0.01), respectively. The administration of rhDNase once daily and twice daily improved forced expiratory volume in one second during the study by a mean (+/- SD) of 5.8 +/- 0.7 and 5.6 +/- 0.7 percent, respectively. None of the patients had anaphylaxis. Voice alteration and laryngitis were more frequent in the rhDNase-treated patients than in those receiving placebo but were rarely severe and resolved within 21 days of onset.

CONCLUSIONS

In patients with cystic fibrosis, the administration of rhDNase reduced but did not eliminate exacerbations of respiratory symptoms, resulted in slight improvement in pulmonary function, and was well tolerated.

Oral absorption of omega-3 fatty acids in patients with cystic fibrosis who have pancreatic insufficiency and in healthy control subjects

Dietary supplementation with fish oils high in the omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, may have an antiinflammatory effect. We determined whether patients with cystic fibrosis (CF) could incorporate omega-3 fatty acids into their plasma and cell membrane phospholipids without adverse effects. In this double-blind study, 12 patients with pancreatic insufficiency who have CF (mean age, 12.2 +/- 5.4 (SD) years) and 13 subjects without CF (mean age, 13.4 +/- 6.3 (SD) years) were randomly assigned to ingest 8 gm daily of either encapsulated fish oil (3.2 gm of eicosapentaenoic acid and 2.2 gm of docosahexaenoic acid daily) or olive oil ethyl esters for 6 weeks. Two of seven and two of five patients with CF who received fish and olive oils, respectively, and one of eight and none of five subjects without CF discontinued taking the capsules before 6 weeks because of eructation or diarrhea. Significant incorporation of omega-3 fatty acids into plasma and erythrocyte membrane phospholipids was observed in subjects with and those without CF randomly assigned to the fish oil treatment. For example, in subjects randomly assigned to receive fish oil, the eicosapentaenoic acid/arachidonic acid ratio in plasma increased 9.8-fold, from 0.04 +/- 0.02 (mean +/- SEM) to 0.39 +/- 0.11 (p = 0.02), in the patients with CF (n = 7) and 23.0-fold, from 0.04 +/- 0.01 to 0.92 +/- 0.17 (p = 0.001), in the subjects without CF (n = 8) who received fish oil (p = 0.02, patients with CF vs subjects without CF at 6 weeks). No clinically or statistically significant changes from baseline were observed in platelet aggregation or levels of vitamin E or A in subjects who received fish oil. Future studies are indicated to determine whether omega-3 fatty acid enrichment provides a clinically beneficial antiinflammatory effect in patients with CF.

Outcome measures for clinical trials in cystic fibrosis. Summary of a Cystic Fibrosis Foundation consensus conference

The CFF Consensus Conference concluded with a summary of those outcome measures that would be most useful in studies of patients 6 years of age and older and those measures that would be most useful in studies of the younger population (< 6 years of age) (Table). These measures were further divided into biologic markers most appropriate for initial (phase I and phase II) clinical trials and those especially useful in large, multicenter (phase III) pivotal trials. There is an ongoing need to improve the accuracy and validity of currently available measures of biologic activity and clinical efficacy in CF, especially in the younger population. The conference participants recommended that the following eight issues be addressed as soon as possible: (1) definition of pulmonary exacerbation, (2) broadly applicable methods of testing pulmonary function in small children (ideally a single test for all ages), (3) a comprehensive severity-of-disease score for young children, (4) reliable methods of quantifying chest x-ray and CT scan changes in young patients, (5) simple, inexpensive measures of lung inflammation, (6) a centralized, uniform approach to the establishment of data monitoring committees, (7) a quality of well-being scale for small children, and (8) reliable, reproducible aerosol delivery systems with defined characteristics. In addition, participants recommended that better methods be developed for assessing patients' adherence to research protocols.

Efficacy and safety of short-term administration of aerosolized recombinant human deoxyribonuclease in patients with cystic fibrosis

Chronic endobronchial bacterial infection evokes purulent airway secretions in patients with CF. The viscoelastic properties of these secretions is primarily due to the presence of polymerized DNA from degenerating leukocytes. Recombinant human DNase I (rhDNase) reduces the viscosity of CF sputum in vitro. To test the hypothesis that rhDNase would improve pulmonary function in children and adults with CF, we compared the efficacy and safety of 10-day administration of three doses of aerosolized rhDNase (0.6, 2.5, or 10.0 mg twice daily) in 181 outpatients using a randomized, placebo-controlled parallel design. Forced vital capacity (FVC) improved 10 to 12% (p < 0.05 to 0.001), and forced expiratory volume in one second (FEV1) improved 10 to 15% (p < 0.001) across all doses of rhDNase compared with placebo. The magnitude of effect was dose dependent for both FVC and FEV1 through study Day 21 (p < 0.001). rhDNase was associated with a decreased perception of dyspnea and an improved perception of well-being. No patients developed detectable anti-rhDNase antibodies or bronchial reactivity to rhDNase. Some patients experienced mild upper airway irritation, but no major adverse events were reported. Administration for 10 days of aerosolized rhDNase to pediatric and adult outpatients with CF improves lung function and is well tolerated. Although all three doses were efficacious, the greatest improvement in FEV1 and FEV1/FVC ratio was demonstrated in the 2.5 and 10.0 mg rhDNase treatment groups.

Efficacy of aerosolized tobramycin in patients with cystic fibrosis

BACKGROUND

Direct aerosol delivery of aminoglycosides such as tobramycin to the lower airways of patients with cystic fibrosis may control infection with Pseudomonas aeruginosa and improve pulmonary function, with low systemic toxicity. We conducted a randomized crossover study to evaluate the safety and efficacy of aerosolized tobramycin in patients with cystic fibrosis and P. aeruginosa infections.

METHODS

Seventy-one patients with stable pulmonary status were recruited from seven U.S. centers for the treatment of cystic fibrosis and randomly assigned to one of two crossover regimens. Group 1 received 600 mg of aerosolized tobramycin for 28 days, followed by half-strength physiologic saline (placebo) for two 28-day period. Group 2 received placebo for 28 days, followed by tobramycin for two 28-day periods. Pulmonary function, the density of P. aeruginosa in sputum, ototoxicity, nephrotoxicity, and the emergence of tobramycin-resistant P. aeruginosa were monitored.

RESULTS

In the first 28-day period, treatment with tobramycin was associated with an increase in the percentage of the value predicted for forced expiratory volume in one second (9.7 percentage points higher than the value for placebo; P < 0.001), forced vital capacity (6.2 percentage points higher than the value for placebo; P = 0.014), and forced expiratory flow at the midportion of the vital capacity (13.0 percentage points higher than the value for placebo; P < 0.001). A decrease in the density of P. aeruginosa in sputum by a factor of 100 (P < 0.001) was found during all periods of tobramycin administration. Neither ototoxicity nor nephrotoxicity was detected. The frequency of the emergence of tobramycin-resistant bacteria was similar during both tobramycin and placebo administration.

CONCLUSIONS

The short-term aerosol administration of a high dose of tobramycin in patients with clinically stable cystic fibrosis is an efficacious and safe treatment for endobronchial infection with P. aeruginosa.

Nutritional assessment and management in cystic fibrosis: a consensus report. The Consensus Committee

This report is a summary of a meeting convened by the Cystic Fibrosis Foundation to develop a consensus among nutrition specialists and cystic fibrosis care givers regarding optimal nutritional management of patients with cystic fibrosis. The first section of the report provides a rationale for emphasizing nutritional management of this genetic disorder. The multiple factors causing malnutrition and a negative energy balance are outlined. The second section provides guidelines for routine assessment of nutrition in these patients. Five categories of nutritional status are defined based on ideal weight for height, age, and gender. These categories are used to formulate a graded response for nutritional intervention. Recommendations are provided for routine dietary supplements, vitamin supplements, and pancreatic enzyme replacement. The primary aim of this report is to educate clinicians as to the importance of frequent assessments and early intervention.

Predictive value of oropharyngeal cultures for identifying lower airway bacteria in cystic fibrosis patients

Identifying lower respiratory pathogens in young, non expectorating cystic fibrosis (CF) patients has been problematic. Bronchial secretions are difficult to obtain, and little is known about lower airway flora in these patients. We collected simultaneous bronchial and oropharyngeal specimens in 43 CF patients in optimal respiratory status, including both expectorating (17) and nonexpectorating (26) patients, to determine the predictive value of oropharyngeal cultures for identifying lower airway pathogens. An additional goal was to characterize the lower respiratory flora of these patients. Predictive values were defined as the proportion of oropharyngeal culture results that accurately reflected the results of bronchial cultures. Predictive values of positive oropharyngeal cultures in nonexpectorating patients were 83% (95% confidence interval 36 to 100%) for Pseudomonas aeruginosa and 91% (59 to 100%) for Staphylococcus aureus. Predictive values of negative oropharyngeal cultures were lower: 70% (48 to 86%) for R aeruginosa and 80% (52 to 96%) for S. aureus. A relatively high proportion of nonexpectorating CF patients less than 10 yr old had R aerusginosa (11 of 24, 46%) or Klebsiella species (5 of 24, 21%) in their lower airways. The isolation of Klebsiella was associated with younger age (p = 0.03) and recent administration of antistaphylococcal antibiotics (p = 0.05). Our results suggest that oropharyngeal cultures yielding R aeruginosa or S. aureus are highly predictive, but such cultures lacking these organisms do not rule out the presence of these pathogens in the lower airways of CF patients.

Cyclic nucleotide responses in control and cystic fibrosis labial glands

Adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) levels were measured in labial gland slices from controls and patients with cystic fibrosis (CF). Incubation in vitro with 10 microM epinephrine, 50 microM isoproterenol, or 10 microM carbachol increased cAMP levels by 2.3-fold, 3.1-fold, and 1.8-fold, respectively, in control glands and by similar amounts in CF glands. The only statistically significant CF-related difference was a decreased response to isoproterenol. Addition of MIX (3-isobutyl-1-methylxanthine) increased cAMP levels in control and CF glands by an order of magnitude under all conditions but did not eliminate the CF-related decrease in cAMP level obtained with isoproterenol. cGMP levels were measured only in the presence of MIX. Incubation with carbachol nearly doubled cGMP levels in control and CF glands but only the control gland response approached statistical significance (P = 0.06). cGMP levels in CF glands were nearly threefold greater than those in control glands, and disease-related differences obtained in the presence of carbachol and isoproterenol were statistically significant.

The effect of respiratory viral infections on patients with cystic fibrosis

We examined, in a 2-year prospective study, the frequency of respiratory viral infections in 19 school-age patients with cystic fibrosis and their unaffected siblings. At 2-month intervals throughout the study period, pulmonary function tests, oropharyngeal cultures, and serologic tests for respiratory viruses were performed in all subjects. Quantitative sputum cultures for bacteria were performed in subjects with cystic fibrosis. The same laboratory specimens were also collected at the time of all acute respiratory illnesses. Over the 2-year period, 398 viral cultures and serum samples were collected, 210 from patients with cystic fibrosis and 188 from their siblings. The frequency of culture-documented and seropositive viral infections was not significantly different between patients with cystic fibrosis and their siblings. The patients with the highest frequency of viral infection were younger and had the lowest rate of decline in lung function and severity score. We conclude that school-age patients with cystic fibrosis are no more susceptible to viral infections than their unaffected siblings. We were unable to demonstrate any significant adverse effect of respiratory viral infections on pulmonary function in 19 patients with cystic fibrosis aged 5 to 21 years.

Safety of aerosol tobramycin administration for 3 months to patients with cystic fibrosis

To determine the potential toxicity of prolonged aerosol tobramycin administration, 22 patients with cystic fibrosis were monitored while receiving inhaled tobramycin three times a day for 12 weeks. Prior to, four times during administration and approximately 6 weeks after discontinuation of treatment, we assessed pulmonary function, weight, height, body temperature, eighth cranial nerve function, serum creatinine, blood urea nitrogen, urinary creatinine clearance, plasma iothalamate clearance, urinary beta-2 microglobulin concentration, and Pseudomonas aeruginosa density in sputum. There was no detectable laboratory evidence of nephrotoxicity. Neither a decrease in auditory acuity (range 250-20,000 Hz) nor vestibular dysfunction was detected. Pulmonary function tests significantly improved during the first month in all subjects (P less than 0.05) but returned to enrollment values by the end of the 12th week of administration of tobramycin aerosol. Sputum P. aeruginosa density initially decreased from a mean of 10(7) cfu/gm to a mean of 10(4) cfu/gm after 2 weeks of aerosol tobramycin administration and remained significantly below the enrollment value throughout. Coincident with the reduced bacterial density, a reduction in cough frequency and sputum production, as well as a weight gain was observed. Seventy-three percent of the patients with sputum P. aeruginosa isolates susceptible to tobramycin on enrollment yielded resistant organisms during aerosol administration. However, 1 year later all sputum P. aeruginosa isolates obtained from patients were susceptible to tobramycin. We conclude that thrice daily aerosol tobramycin administration for 3 months is not associated with detectable eighth cranial nerve or renal toxicity. Transient emergence of tobramycin resistant P. aeruginosa may occur.

Potassium release in labial glands from controls and patients with cystic fibrosis

Labial glands from patients with cystic fibrosis (CF) were tested for a disease-related decrease in cholinergically-induced K release. Labial gland slices from normal controls and patients with cystic fibrosis were incubated in vitro in the presence or absence of cholinergic and adrenergic agonists and with or without a phosphodiesterase inhibitor. Both control and CF glands released K in response to cholinergic stimulation only; no K release response was detected to alpha- or beta- adrenergic stimulation. In contrast to previous results reported for parotid glands, no CF-related decrease in cholinergically-induced K release was detected. Both normal and CF glands released significantly less K with carbachol stimulation in the presence of the phosphodiesterase inhibitor. Overall, the results suggest considerable interglandular differences in disease sensitivity and functional regulation of K release.

Use of bacterial antigen detection in the diagnosis of pediatric lower respiratory tract infections

Two immunochemical methods were used to identify Haemophilus influenzae and Streptococcus pneumoniae capsular antigens in the urine and serum of 162 children with acute lower respiratory tract infection. These methods were compared with standard bacterial blood culture. Viral and mycoplasma cultures of respiratory secretions were obtained simultaneously to determine the frequency of antigenuria at the time of nonbacterial acute lower respiratory tract infection. Urine from groups of well children and children with acute otitis media was tested for capsular antigens to determine the incidence of antigenuria. Antigenuria was found in 24% of children 2 months to 18 years of age with acute lower respiratory tract infection compared with a 2% incidence of bacteremia. Antigenuria was found in 4% of asymptomatic children and 16% of children with acute otitis media. One third of children with symptoms of acute lower respiratory tract infection and viral isolates from the oropharynx had bacterial antigenuria. The sixfold increase in frequency of bacterial antigenuria in children at the time of lower respiratory symptoms suggests that bacterial acute lower respiratory tract infection may be more common than identified by traditional culture techniques. Because bacterial antigen may come from other sites such as the middle ear, further studies are needed to determine the role of antigen detection in the diagnosis of pediatric acute lower respiratory tract infection.

Comparative monovalent cation transport in neonatal and adult red blood cells

Active transport of Na and K under physiologic and maximally stressed conditions was identical in normal adult red blood cells (RBC) and term neonatal erythrocytes. These results are consistent with the previous observation that Na-K ATPase is the same in normal adult RBC and term neonatal erythrocytes. These data, however, are at variance with a previous observation that active K transport is impaired in neonatal erythrocytes. The most reasonable explanation for this difference relates to inherent problems with the use of radioisotopes which were used in previous in vitro studies of cation transport.

Bacterial endocarditis due to penicillin-resistant Streptococcus viridans

Bacterial endocarditis remains a formidable diagnostic and therapeutic problem for clinicians. Streptococcus viridans still accounts for 45 to 50 per cent of all cases and between 5 to 10 per cent of all clinical isolates of Streptococcus viridans from patients with bacterial endocarditis may be relatively resistant to penicillin. The case of a 9-year-old child with Tetralogy of Fallot and a Waterston shunt who subsequently developed bacterial endocarditis due to penicillin-resistant Streptococcus viridans following failure of oral penicillin dental prophylaxis is presented. In the face of penicillin resistance, additional considerations for workup, including microbiological assays for antimicrobial synergism become necessary in the selection of a therapeutic regimen.