Polymeric structure of human respiratory mucin: studies on two protein components released upon reduction of disulfide bonds.

A major mucus glycoprotein (mucin) was purified from the tracheobronchial secretions of an asthmatic patient. Upon SDS-composite gel electrophoresis, the purified native (non-reduced) mucin gave a single band. SDS-gel electrophoresis on 6% polyacrylamide gels showed the absence of low molecular mass protein contaminants. However, SDS-PAGE (6% gels) of the reduced mucin showed the presence of a major high molecular mass mucin component and two low molecular mass components of 118 and 70 kDa, respectively. The 118 and 70 kDa components were purified by preparative electroelution of the reduced mucin. These components were also separated from the reduced mucin by gel-permeation chromatography on a Superose 6 column. Chemical compositional analyses showed that the 118 kDa component was a glycoprotein while the 70 kDa component was non-glycosylated. The effect of disulfide bond reduction on mucin structure and the hydrophobic probe binding properties of native and reduced mucin were studied using the fluorescent probe technique. Mansylphenylalanine was used as the fluorescent probe. The native mucin showed the presence of a large number of low-affinity (KD approximately 10(-5) M) binding sites for the probe. On the other hand, reduced-alkylated mucin containing the 118 and 70 kDa components showed the presence of additional high-affinity (KD approximately 10(-6) M) binding sites as well as low-affinity binding sites for the probe. Reduced alkylated mucin devoid of the 118 and 70 kDa components showed the presence of only low-affinity binding sites. These observations suggest that the availability of high-affinity probe binding sites upon reduction of mucin disulfide bonds may be either due to binding of the probe to the released component(s) and/or due to noncovalent interaction of the released component(s) with the mucin causing a conformational change in the mucin structure. Thus, the 118 and 70 kDa components appear to be an integral part of the total polymeric structure of the human respiratory mucin.

Biophysical characterization of mucin components HTM-1 and HTM-2 from tracheobronchial secretions of cystic fibrosis patients.

Mucins present in the tracheobronchial secretions are responsible for the viscoelastic properties of the mucus. Any changes in the mucin structure may alter the physical properties of mucus and hence its function. Previous studies from this laboratory have reported the isolation and characterization of a major mucin component (HTM-1) and a minor, novel mucin component (HTM-2) from the tracheobronchial secretions of cystic fibrosis (CF) individuals. In the present study, the macromolecular properties of the CF mucin components HTM-1 and HTM-2 were further investigated using biophysical methods. Dynamic light scattering studies showed that CF HTM-1 and HTM-2 had a greater extended structure in buffer containing 0.10 and 0.15 M NaCl than that observed in the presence of 0.03 M NaCl. Also, CF HTM-1 had a compact configuration in the presence of 5 and 10 mM Ca2+, while under similar experimental conditions, the structure of CF HTM-2 was unaffected, indicating differences in the macromolecular properties of CF mucin components. Fluorescent probe binding studies revealed that CF HTM-1 had more hydrophobic probe binding domains than those observed for CF HTM-2. In summary, both biochemical and biophysical characterization suggests structural differences between the CF HTM-1 and HTM-2 components.

Physicochemical characterization of a minor mucin component from cystic fibrosis tracheobronchial secretions.

A minor mucin glycoprotein component (HTM-2) was purified from the tracheobronchial secretions of two cystic fibrosis patients using a protocol established in our laboratory. The secretions were solubilized in 0.1 M Tris-HCl buffer (pH 7.5) containing 0.22 M potassium thiocyanate and fractionated on a Bio-Gel A-5m column, followed by digestion with DNAase, rechromatography on the same column and chromatography on hydroxyapatite which resolved the major mucin (HTM-1) from the minor mucin component (HTM-2). The mucin component HTM-2 was further purified using Superose 6 chromatography. SDS-composite gel (2% polyacrylamide + 0.5% agarose) and 6% polyacrylamide gel electrophoresis showed that the purified HTM-2 was totally free of low-molecular-weight contaminants. Equilibrium density sedimentation centrifugation of purified HTM-2 using CsCl gradients also showed the absence of proteoglycans and other low-molecular-weight proteins. Comparison of carbohydrate and amino acid compositions of the two mucin components indicated that HTM-2 was quite different from the major mucin, HTM-1, reported earlier from our laboratory (Biochemistry, 24, 7334, 1985). This suggested that HTM-2 has a different polypeptide core and is perhaps a different gene product. The effects of 6 M guanidine-HCl and different concentrations of NaCl on the molecular size of HTM-2 and its ability to form aggregates was also investigated using the technique of static light scattering. In buffer containing 6 M guanidine-HCl, HTM-2 had a weight-average molecular weight of approximately 4.5 x 10(6). However, in the presence of buffer containing 0.03, 0.10 or 0.15 M NaCl, the molecular weight of HTM-2 was estimated to be approximately 11 x 10(6). These data suggest aggregation of HTM-2 in the presence of a range of NaCl concentrations. In contrast to HTM-1, which is a more anionic glycoprotein, the apparent molecular size of HTM-2 did not decrease at the higher NaCl concentration.

Detection of distinct species in purified human respiratory mucin using monoclonal antibodies.

The purpose of this investigation was to demonstrate the presence of different species (subpopulations) in the purified human tracheobronchial mucin (HTM-1). Mucin was highly purified from sputum specimens collected from a cystic fibrosis (CF) patient using a protocol involving sequential chromatography on Bio-Gel A-5m and hydroxylapatite columns. SDS-composite gel electrophoresis followed by periodic acid-Schiff's reagent staining was unable to detect mucin species. However, using enzyme-linked immunoelectrotransfer blot (EITB) method and polyclonal antibodies raised against HTM-1, at least four different migrating mucin species were detected. Further immunological characterization of these mucin species was carried out using a library of 16 monoclonal antibodies (MAbs) developed against the purified mucin. Nine MAbs belonged to the IgM class, two MAbs were IgG1, one IgG2a and remaining four were of the IgG3 subclass. Periodate oxidation of the mucin antigen was used to establish the nature of the mucin epitopes recognized by the MAbs. 11 MAbs recognized carbohydrate epitopes in the mucin molecule that were sensitive to periodate, while five MAbs reacted with periodate resistant carbohydrate epitopes or the protein portion of the mucin molecule. Enzyme-linked immunoelectrotransfer blot analysis of the MAbs against HTM-1 showed the presence of at least three distinct mucin species. Chromatography of the mucin on immunoaffinity columns (MAbs H(13.3), M(33.3) and CCK 061 conjugated to CNBr-activated Sepharose 4B), followed by ELISA and EITB analyses, established the mucin species recognized by the antibodies. These experiments further indicated that both unique and shared epitopes were present in the mucin species. These monoclonal antibodies may provide a promising approach to differentiate the secretory products of the tracheobronchial tree.

Pulmonary function abnormalities in intentional spray paint inhalation.

To investigate the effects of intentional hydrocarbon inhalation on lung function, a preliminary study involving ten spray paint abusers was conducted. Mean duration of the inhalation was 34.9 months; mean frequency was 3.2 times per week. Pulmonary function testing (PFT) consisted of flow studies, lung volumes, single-breath carbon monoxide diffusing capacity (Dsb), airway resistance and airway conductance. An exercise provocation was followed by repetition of the PFT, except for Dsb. Our results revealed an obstructive ventilatory pattern in 90 percent of the subjects. In seven patients, there was a significant increase of airway resistance prior to exercise. In five of the ten patients, exercise provocation produced an increase in residual volume. Five of six subjects receiving a trial of a bronchodilator had significant improvement of obstruction. These findings suggest that intentional inhalation of spray paint may produce abnormalities in pulmonary function. These abnormalities may improve after use of a bronchodilator.

Production and characterization of monoclonal antibodies to purified deglycosylated cystic fibrosis respiratory mucin: evidence for the presence of four immunologically distinct epitopes.

Respiratory mucus glycoproteins (mucins) were purified from the tracheobronchial secretions of three Cystic Fibrosis (CF) patients. The mucins were completely deglycosylated by treatment with trifluoromethanesulfonic acid and subsequent treatment with alpha-N-acetylgalactosaminidase. Over thirty hybrid clones secreting antibodies against the deglycosylated mucin (DGM) were obtained using standard hybridoma techniques. Hybrids with positive identification for CF-DGM were cloned twice using limiting dilution method to ensure the monoclonal nature of the antibodies. Eight stable clones (1a, 1b, 10a, 10c, 10d, 10e, 29d, and 30e) secreting monoclonal antibodies (MAbs) showing specificity of reaction to CF-DGM were obtained. Two clones, 29d and 30e, secreted antibodies of the IgM class while the other six clones secreted antibodies of the IgG1 subclass. Denaturation and reduction experiments suggested that MAbs 1b, 10e, 29d and 30e were directed against a given sequence of amino acids in the DGM while the other four MAbs, in addition to being sequence specific, were also conformation dependent. Further, competitive binding radioimmunoassays suggested that MAbs 1b, 10e, 29d and 30e recognize four distinct epitopes in the peptidic core of CF respiratory mucin. In summary, the MAbs may provide a promising approach to elucidate the structure of the polypeptide backbone of human respiratory mucins as well as for the screening of cDNA libraries for clones secreting mucin(s).

Asthma in children: emergency management.

We review the pathophysiological alterations at work in asthma and outline pharmacological agents that are available for emergency therapeutic intervention, offering some general principles for management. A combined overview of predictors of outcome in asthmatic episodes in children also is presented.

Normal pulmonary function after baby powder inhalation causing adult respiratory distress syndrome.

We report a case of baby powder inhalation (BPI), causing adult respiratory distress syndrome (ARDS) in a 16-month-old girl, with follow-up after six years. Pulmonary function studies in the child and her monozygotic twin, used as a control, were normal. The testing consisted of diffusing capacity to carbon monoxide and body plethysmography, the latter performed prior to and following an exercise challenge. A review of the literature of talcum aspiration indicates that the management of this condition is largely supportive. The long-term effects of BPI remain unknown, since serial follow-up studies are not available.

Lipoid pneumonia secondary to baby oil aspiration: a case report and review of the literature.

Baby oil is a common household product that is frequently used when there are infants or toddlers in the house. However, it is often overlooked as a potential source of danger to these youngsters. In 1983, 36,700 cases of ingestion were reported to the poisoning surveillance and epidemiology branch of the Food and Drug Administration. Topical preparations used in the care of infants accounted for 480 of the cases. Ten percent of these required hospitalization. In 36 cases, the product ingested was baby oil. This figure does not include baby lotions and other skin products with a mineral oil base. Aspiration of mineral oil, the main component of baby oil, has been described as a cause of lipoid pneumonia and oleomas. However, there is very little information in the modern literature concerning acute lipoid pneumonitis in children. We herein present a patient with lipoid pneumonia caused by aspirated baby oil, who followed a severe clinical course. The paucity of information regarding this subject points to the need for increased public and physician awareness of the problem and for their direct participation in the prevention of this potentially fatal condition.

Potential permanent respiratory sequela of Stevens-Johnson syndrome in an adolescent.

Respiratory involvement is a frequent complication of the Stevens-Johnson Syndrome (SJS); however, there are no reports of persisting pulmonary sequelae following recovery. We present a case report of an adolescent girl with a history of clinically inactive hyperactive airway disease who developed persistent, severe obstructive pulmonary disease following an episode of SJS. This case may represent a permanent respiratory sequela.

Dyskinetic cilia syndrome: clinical, radiographic and scintigraphic findings.

The clinical, electron microscopic and radiographic data of 9 patients with dyskinetic cilia syndrome (DCS) are presented. Scintigraphic evaluation of mucociliary dynamics in six patients showed evidence of dyskinesia. Ventilation and perfusion studies were performed to evaluate obstructive lung disease. Retrospectively, bronchiectasis could be detected in 77% of the patients by analysis of the chest radiograph and lung scintigraphy, and bronchography potentially avoided in the seven patients who underwent this procedure.

Clinical characteristics, pathophysiology, and management of hydrocarbon ingestion: case report and review of the literature.

Accidental ingestion of hydrocarbons is an important cause of childhood poisoning. Due to the number of hydrocarbon products available as solvents, fuels, and cleaning agents, increased awareness is necessary on the part of health caretakers. The scope of complications involving the respiratory system in petroleum products ingestion is frequently overlooked. Physicians may thus apply standard therapeutic modalities used in treating common poisonings to the child who drank a petroleum distillate. Prompt recognition of presenting symptoms and understanding of pathophysiology are important to planning and providing treatment. The two cases of hydrocarbon ingestion reported in this paper illustrate the wide spectrum of problems associated with this condition. The pathophysiology, current management, and a review of the literature of hydrocarbon ingestion are presented.

Use of ketamine in asthmatic children to treat respiratory failure refractory to conventional therapy.

We treated two pediatric patients suffering respiratory failure associated with status asthmaticus. Neither patient responded to maximal bronchodilatory therapy and mechanical ventilation; however, continuous infusion of ketamine (1.0 to 2.5 mg/kg X h) immediately improved airway obstruction. Ketamine appears to increase catecholamine levels and directly relax bronchial smooth muscle. Except for increased secretions during the infusion, our patients showed no immediate or long-term sequelae from ketamine therapy. However, ketamine should only be used for asthmatics whose respiratory failure does not respond to conventional management and mechanical ventilation.

Evidence of hydrophobic domains in human respiratory mucins. Effect of sodium chloride on hydrophobic binding properties.

Hydrophobic binding properties of purified human respiratory mucins were studied by the fluorescence probe technique using mansylphenylalanine (Mns-Phe) as the fluorescent probe. Mucins were purified from tracheobronchial secretions of cystic fibrosis (CF) and asthmatic patients, as well as from individuals with normal lungs, according to a protocol earlier established in our laboratory. Purified mucins were subjected to reduction-alkylation and Pronase digestion to study the effects of these treatments on the hydrophobic properties of the mucins. In addition, the effects of increased NaCl concentration on the hydrophobic properties of native and reduced-alkylated mucins were also investigated. Native mucins showed evidence of a large number of low-affinity (KD approximately 10(-5) M) binding sites for the hydrophobic ligand Mns-Phe and had between 40 and 50 binding sites/mg of mucin. Reduction of mucin using dithiothreitol in the presence of 6 M guanidine hydrochloride and subsequent alkylation with iodoacetamide apparently caused marked conformational changes in the mucin molecules as revealed by the presence of both high-affinity (KD approximately 10(-6) M) and low-affinity (KD approximately 10(-5) M) binding sites for the probe and an increase in the number of probe binding sites. Pronase digestion of the native and reduced-alkylated mucins almost completely eliminated binding of the fluorescent probe to the mucins, showing that the binding sites are on the nonglycosylated, Pronase-sensitive portion of the mucin molecules. Increasing NaCl concentrations (0.03-1.0 M) did not appreciably alter the native mucin-induced Mns-Phe fluorescence, while that of the reduced-alkylated mucin-induced Mns-Phe fluorescence was progressively increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect on airway resistance of ketamine by aerosol in guinea pigs.

The effect of aerosolized ketamine hydrochloride was investigated by measuring airway resistance with a two-compartment plethysmograph in guinea pigs challenged with histamine. In the first phase of the study, treatment with ketamine prior to histamine challenge did not protect against elevation of airway resistance. In the second phase of the study, ketamine inhalation after histamine challenge did not significantly diminish airway resistance. Aerosolized ketamine is not recommended for use in human subjects with asthma.

Pneumonia caused by a newly recognized pseudomonad in a child with chronic granulomatous disease.

A pseudomonad was isolated from the pleural fluid and pulmonary decortication tissue of a 5-year-old child with chronic granulomatous disease. Although the isolate was phenotypically similar to Pseudomonas cepacia, its biochemical profile was more similar to that of Pseudomonas pickettii biovar 2. Its slow growth rate, ability to hydrolyze urea rapidly, and lateral and polar flagellar pattern were suggestive of Oligella ureolytica (formerly CDC group IVe). The cellular fatty acid composition was similar to that of P. cepacia and Pseudomonas gladioli, except for the presence of dodecanoic acid. Numerical analysis of the fatty acid data supported the interrelatedness of the isolate with other species of the pseudomallei group (rRNA homology group II) of Pseudomonas. The organism described in this report is an addition to the growing list of catalase-positive organisms which can potentially cause severe morbidity in patients with chronic granulomatous disease.

Growth hormone improves weight velocity and height velocity in prepubertal children with cystic fibrosis.

We undertook this study to determine if growth hormone treatment of prepubertal children with cystic fibrosis could improve their height and weight. Nine prepubertal children with cystic fibrosis were treated with human recombinant growth hormone for one year. Results obtained during this year were compared to similar measurements made for each patient for the one year prior to the treatment year. Anthropometric data including: height, height velocity, weight, weight velocity and skin fold thickness were measured at three month intervals. Pulmonary function and skeletal muscle strength were measured at three month intervals. Glucose tolerance was evaluated by HbAlc and by fasting blood glucose and insulin levels every three months. Our results demonstrate that growth hormone treatment resulted in significant improvement in height velocity and height Z scores. Weight increased in all subjects, with a significant increase in weight velocity (year prior to treatment = 1.7+/-1.0 kg/yr, treatment year = 3.8+/-1.6 kg/yr; p=0.03). Measurements of skin fold thickness suggests that lean body mass improved with growth hormone treatment. Pulmonary function improved in all but two patients, whose pulmonary function remained the same and muscle strength improved in all subjects. These results suggest that growth hormone used in prepubertal children with cystic fibrosis can improve height and weight and may improve lean body mass.