Characterization of Films Produced with Cross-Linked Cassava Starch and Emulsions of Watermelon Seed Oils

Starches are promising molecules in the production of edible films. However, the hydrophilic nature of these materials is among the main limitations of packaging based on natural polymers. An underexplored alternative is the incorporation of emulsions. This work aimed to produce films based on crosslinked cassava starch with emulsions based on watermelon seed oil (WSO) extracted with pressurized ethanol. The effect of incorporating watermelon seed oil emulsion (WSOE) on the microscopic, structural, mechanical, hydrophilic, and thermal properties of films was analyzed. The internal structure and roughness of the films were significantly affected by increasing WSOE concentration. The WSOE incorporation increased the elongation capacity of the films and reduced the strain at break. WSOE concentrations did not significantly affect the water solubility, permeability, and X-ray diffraction but decreased the wettability of the films. The analysis of the thermal properties showed that the films did not present phase separation in the studied temperature range. Overall, WSOE improved the properties of the films based on cross-linked cassava starch, but it is necessary to optimize the production conditions of the films. These materials may potentially be used as biodegradable food packaging, controlled-release films, and edible coatings in food protection.

Lung mucociliary transport in asymptomatic asthma: effects of inhaled histamine

Bronchial mucociliary clearance (CB) and tracheal mucus velocity (TMV) were measured during the course of repeated inhalations of histamine in six subjects with asthma who had no symptoms in a double-blind, crossover study with a radioaerosol technique. Subjects inhaled a technetium 99m-labeled ferric oxide aerosol with an aerodynamic diameter of approximately 8 microns. CB was recorded for 2.5 hours with a gamma camera, and TMV measured with a multidetector probe situated over the extrathoracic trachea. Histamine was administered repeatedly in concentrations previously shown to produce a 20% fall in forced expired volume in 1 second and at intervals allowing 90% recovery of pulmonary function. Histamine produced a 28% increase in CB (p less than 0.001, analysis of variance) and an 87% increase in TMV (p less than 0.001, analysis of variance) above control values, which was not significantly different from that previously observed in normal subjects receiving significantly higher concentrations of histamine. We conclude that histamine stimulates the mucus transport mechanism in subjects with asthma and that there is a relative hypersensitivity to histamine when these subjects are compared with normal subjects.

Clinical aerosols II. Therapeutic aerosols

The current uses of clinical aerosols such as water, saline, mucolytics, bronchodilators, cromolyn sodium, corticosteroids, and antimicrobials have been reviewed. The benefits of water, saline, and detergent aerosols continue to be surrounded by uncertainty and controversy. Aerosolized mucolytic and proteolytic agents have not been conclusively shown to be of substantial value in the improvement of respiratory disorders. Favorable bronchodilator therapy is achieved with aerosols of certain sympathomimetic and anticholinergic agents. However, successful therapy depends on the dose administered and the site of aerosol deposition in the lung. The prophylactic use of cromolyn sodium in patients with asthma is another useful application of aerosols. Topically active corticosteroid aerosols are increasingly being used since they may reduce risks of systemic effects from corticosteroids. Research on uncommonly aerosolized agents has widened the spectrum of therapeutic applications of aerosols.

Clinical aerosols. I. Characterization of aerosols and their diagnostic uses

Characterization of an aerosol is of major importance for the understanding of its pathogenic, diagnostic, or therapeutic effect. The parameters necessary for such characterization as well as the methods for obtaining them are reviewed. The factors that determine site of deposition in the human lung are discussed. Further, we have reviewed methods employed to produce aerosols for diagnostic, therapeutic, and clinical research uses. Basic and relatively simple knowledge of aerosol characterization can increase the usefulness of clinical aerosols. Using this knowledge, general principles for aerosol administration are developed. Finally, the application of aerosols in the diagnosis of respiratory diseases is presented; these aerosols include contrast agents, radioactive aerosols, and bronchospastic agents.

Respiratory neuromuscular response to CO2 rebreathing with inspiratory flow resistance in humans

The effects of inspiratory flow resistance on mouth occlusion pressure (P0.15) and diaphragmatic EMG (EMGdi) responses to CO2 rebreathing were studied in normal subjects. Occlusion pressures were measured 150 msec after onset of an inspiratory effect; EMGdi was analyzed as a moving time average and quantified in terms of peak activity and rate of rise of activity. After a control CO2 response was obtained in each subject, rebreathing was repeated 30 min later with either of two inspiratory flow resistive loads, 5 cm H2O/L/sec (IR5) and 14 cm H2O/L/sec (IR14). With IR5 (6 subjects), the P0.15 response was decreased in two subjects, unchanged in two, and increased in two; peak EMGdi was unchanged in all, while rate of rise of EMGdi response decreased in 4 of the 6 subjects. With IR14 (6 subjects, 9 runs), the P0.15 response was not decreased in any subject, remained unchanged in 4, and increased in 5; peak EMGdi response to rebreathing in all runs was, again, unchanged by this load, but rate of rise of EMGdi was decreased in 3 and unchanged in 6. The inspiratory off-switch threshold as reflected by peak diaphragmatic activity was not changed by inspiratory flow resistance, whereas inspiratory neural drive as reflected by the the rate of rise of activity was decreased in some subjects. The decrease in inspiratory drive without change in inspiratory off-switch threshold resulted in prolongation of inspiration in an attempt to effect efficient lung expansion. However, the defense of ventilation during rebreathing with both resistances appeared to mainly depend on the response of inspiratory muscle force (P0.15), since in 7 of the 7 runs in which the P0.15 response was significantly increased from control, the ventilatory response was not decreased.

Calculated deposition of inhaled particles in the airway generations of normal subjects

Detailed regional deposition of inhaled particles in the human lung is calculated for individual airway generations. The calculations are based on Landahl's deposition model as applied to the morphometric lung model of Weibel. We consider primarily deposition patterns of iron oxide particles with diameters ranging between 1 and 10 micrometers, but we also calculate patterns of deposition for bis(2-ethylhexyl) sebacate particles with diameters as small as 0.2 micrometers. We obtain good agreement between predicted values and observed values for alveolar retention of inhaled iron oxide particles with 64 and 20% of total deposition predicted to occur in nonciliated airways for 2- and 5-micrometer particles, respectively. This is compared with 48 +/- 9 and 27 +/- 10% for the measured values. Calculated values for total lung deposition of small bis(2-ethylhexyl) sebacate particles agree well with experimental data. The calculations show a minimum in deposition occurring for particle diameters of 0.5 micrometers, which is in agreement with observations. A calculation of surface concentration of deposited 7.9-micrometer aerodynamic particles reveals a very large concentration occurring at airway generation four. This observation is considered in light of observations that bronchial carcinomas occur in this vicinity of the lung.

Diaphragmatic EMG response to isocapnic hypoxia and hyperoxic hypercapnia in humans

The EMGdi response to both isocapnic hypoxia and hyperoxic hypercapnia was studied in the same sitting in six normal subjects. Rebreathing methods achieving "open loop" conditions were used. EMGdi was quantified as a moving time average. In almost all subjects, during hypoxia changes in EMGdi were inversely and hyperbolically related to changes in PAO2. When EMGdi was plotted against extrapolated O2 saturation, the relationship was linear in all subjects. The EMGdi response to hypoxia was qualitatively similar to the concurrent responses VI and P.15. EMGdi was linearly related to PACO2 during CO2 rebreathing. The slopes of the EMGdi response to decreasing O2 saturation were positively correlated to the slopes of the EMGdi response to PACO2, so that subjects with a low hypoxic response also had a low CO2 response and vice versa. The couplings of neural to muscular and muscular to ventilatory events as assessed by the ratio of the slopes of EMGdi to P.15 and P.15 to VI, respectively, were similar for all subjects and were not related to the degree or type of chemostimulation. The following were our conclusions. (1) EMGdi can be used as an index of respiratory motoneuron drive during hypoxic or hypercapnic breathing in normal humans. (2) The relative degree of responsiveness to hypoxic and hypercapnia stimuli (chemosensitivity) appears to be similar in any given individual. (3) In normal subjects, changes in inspiratory muscle pressure and ventilation are proportionate to changes in inspiratory neural drive as assessed by EMGdi.

Nodular pulmonary sarcoidosis. Clinical, roentgenographic, and physiologic course in five patients

Five cases of nodular pulmonary sarcoidosis are presented. That nodular infiltration represents a reversible stage of sarcoidosis is suggested by the fact that all patients demonstrated roentgenographic resolution of these infiltrates. In four of the five subjects, tests of pulmonary function showed restrictive disease which remained unchanged or worsened despite radiologic clearing, suggesting persistence of active disease or development of residual pulmonary fibrosis. Evidence of obstruction of airways that was unexplained by a history of smoking was present in all of the five subjects.

Relationship between mouth occlusion pressure and electrical activity of the diaphragm: effects of flow-resistive loading

We determined the relationship between mouth occlusion pressure and diaphragmatic electromyography during CO2 rebreathing with and without inspiratory flow resistance. Diaphragmatic electromyography was measured as a moving time average; occlusion pressures were measured 150 msec after onset of an inspiratory effort against a closed airway (P.15). P.15 versus diaphragmatic electromyographic plots during CO2 rebreathing with and without inspiratory flow resistance were linear. In 3 subjects the slope of P.15 versus diaphragmatic electromyography was unchanged with inspiratory flow resistance whereas in 3 others the slope increased, indicating greater inspiratory force for a given degree of diaphragmatic activity. We concluded that under unloaded conditions P.15 is a reliable index of respiratory neural output but may no longer reflect only inspiratory motoneuron drive during mechanical loading.

Quantification of diaphragmatic EMG response to CO2 rebreathing in humans

To determine a reliable quantitative method of measuring diaphragmatic EMG (EMGdi), electrical activity of the diaphragm was obtained via an esophageal electrode during CO2 rebreathing in 6 normal males and processed three different ways: 1) integration (area), 2) as a moving time average, and 3) as a moving time variance. Integrated activity was quantified in terms of total activity and inspiratory activity. In addition, average total activity and average inspiratory activity were calculated. Moving average and moving variance were analyzed in terms of rate of rise (slope) and peak activities. All integration parameters, except average inspiratory activity, were poorly correlated to changes in PCO2, minute ventilation, and inspiratory muscle force, during rebreathing. Moving average and variance responses to rebreathing were linear with high correlation coefficients, with the slope measures showing the overall best correlations. There was no significant difference between average and variance EMGdi parameters in their responses to rebreathing. Time-related quantification of EMGdi, including average inspiratory activity, and particularly moving average and moving variance, appear to be reliable methods for quantitating neural drive to the respiratory muscles during CO2 rebreathing.

Effects of flow-resistive loading on mouth occlusion pressure during CO2 rebreathing

To evaluate mouth occlusion pressure as an index of neural drive to the respiratory muscles that is independent of lung mechanics, the occlusion pressure response to rebreathing was studied in 7 normal subjects under control conditions and during flow-resistive loading. Inspiratory, expiratory, and combined inspiratory-expiratory flow resistances of 5 and 17 cm H2O per liter per sec were studied in 7 normal subjects. Pressure at the mouth was measured 150 msec after the onset of inspiration against the occluded airway. In all subjects, the ventilatory response to CO2 rebreathing was consistenly decreased by the 3 types of resistive loads, and this decrease was often greater with the higher load. In contrast, the occlusion pressure response was usually increased with inspiratory and inspiratory-expiratory resistance, indicating increased inspiratory muscle output due to these loads. With expiratory resistance, the occlusion pressure response was decreased in most of the subjects, suggesting a decrease in muscular output with expiratory loading. The inspiratory muscle pressure response to resistive loading could have been mediated by neural reflex and/or intrinsic muscle mechanisms. Occlusion pressure, therefore, appears to reflect over-all inspiratory neuromuscular output of the respiratory system during CO2 rebreathing, even with the addition of flow-resistive loads. Measures of mouth occlusion pressure provide a distinct advantage over ventilatory parameters in studies of respiratory control mechanisms during mechanical loading.

Phrenic nerve activity and occlusion pressure changes during CO2 rebreathing in cats

Changes in phrenic nerve activity, quantified as a moving time average, PNG(t), were characterized during complete airway occlusion at functional residual capacity (FRC) and compared to simultaneously occurring changes in intratracheal pressure. In anesthetized cats breathing room air and during CO2 breathing, PNG(t) during occlusion was the same as that found during unobstructed breathing until it reached a value approximately corresponding to that at peak inspiration in the preceding unoccluded breath, the rate of change of PNG(t) usually remained the same but in a few cases (2 out of 11) increased. When intratracheal occlusion pressure was plotted as a function of PNG(t), both while breathing room air and during CO2 rebreathing, an approximately linear relationship was obtained. Thus, changes in intratracheas occlusion pressure obtained at FRC parallel changes in phrenic motor nerve activity. Quantification of electrical activity of respiratory nerves as a moving time average provides a means of characterizing changes in the average level of electrical activity during an inspiratory effort.

Inflammatory reaction and airway damage in cystic fibrosis

In cystic fibrosis there is chronic infection and inflammatory reaction in the airways, accompanied by destruction and shedding of airway epithelium. Leukocytes migrate into the airways and some disintegrate, liberating deoxyribonucleoprotein that is incorporated into the gel structure of the bronchial mucus. We compared the status of these processes in cystic fibrosis with that in chronic bronchitis and bronchiectasis, by examining the sputum raised from the lower airways. Measurements also were made on sputum induced in normal subjects. The results indicate that migration of leukocytes into the airways and shedding of damaged airway epithelium were minimal in the normal subjects; they were significant in the patients with chronic bronchitis, higher in those with bronchiectasis, and still higher in those with cystic fibrosis. The large increases found in the total content of DNA and solids in the cystic fibrosis sputum were due to increases in the insoluble fraction containing the whole leukocytes and particulate debris that remained when the sputum mucus gel was solubilized with mercaptoethanol. Despite the large increases in the total content of DNA and solids, the contents of mucus gel components and of deoxyribonucleoprotein from disintegrated leukocytes actually present in the mucus gel structure of the cystic fibrosis sputum were not significantly higher than in the sputum from the patients with chronic bronchitis or brochiectasis.

Effect of elastic loading on mouth occlusion pressure during CO2 rebreathing in man

In 7 normal subjects, mouth occlusion pressure was evaluated as an index of neural drive to the respiratory muscles during CO2 rebreathing, with and without the addition of 2 degrees of elastic loads. During control and loaded rebreathing, changes in both mouth occlusion pressure and ventilation were linearly related to changes in end-tidal PCO2. With elastic loading, the slope of occlusion pressure versus end-tidal PCO2 response consistently increased from control values in all subjects and was greater with the higher load in 6 of 7 subjects. The ventilatory response to elastic loading was variable and inconsistent owing to the variable increase in frequency of breathing, the tidal volume always being diminished. In normal subjects, both mouth occlusion pressure and ventilation appeared to assess neural drive to the respiratory muscles in response to CO2 rebreathing; with elastic loading, only occlusion pressure continued to reflect neuromuscular output. This increased pressure response could have been mediated by neural reflex and/or intrinsic muscle mechanisms. The data suggest that mouth occlusion pressure may be a useful parameter for evaluating neuromuscular control mechanisms under conditions of increased lung elastance.

Disseminated pulmonary blastomycosis in an immunosuppressed patient. Diagnosis by fiberoptic bronchoscopy

A 73-year-old man with malignant lymphoma who was undergoing treatment with systemic chemotherapy presented with an acute, febrile illness associated with cough and sputum production. The patient developed bilateral, diffuse, pulmonary interstitial infiltrates with rapidly progressive respiratory insufficiency. The diagnosis was made by demonstrating Blastomyces dermatitidis in bronchial brush and transbronchial lung biopsy specimens obtained through fiberoptic bronchoscopy.

Deposition and clearance of 2 micron particles in the tracheobronchial tree of normal subjects--smokers and nonsmokers

Deposition and clearance of inhaled particles of iron oxide labeled with (198)Au were studied in 19 normal subjects (10 nonsmokers and 9 smokers). For this purpose, monodisperse aerosols of particles with a 2 mu diameter were produced in a spinning disc atomizer. Thoracic counts and images with a scintillation camera were begun immediately after inhalation of the aerosol and continued for 6 hr. In all subjects, smokers and nonsmokers, the deposition of the particles was uniform throughout both lung fields, with approximately half of the particles deposited in the ciliated airways (tracheobronchial deposition) and half in the nonciliated airways (alveolar deposition). Tracheobronchial clearance in nonsmokers occurred immediately after inhalation, first at a fast rate for particles deposited in the largest and most central airways, and then at a slower rate for particles from the smaller and more peripheral airways. Photoscintigrams showed that the particles cleared steadily with no retention in any area. The general pattern of clearance may be likened to a model of multiple conveyor belts with speed increasing from the peripheral to the central airways in such a way as to prevent "particle jams" at airway confluence points. In smokers, tracheobronchial clearance was delayed for periods of 1-4 hr after inhalation. Furthermore, in contrast with the findings in nonsmokers, significant clearance was still occurring in many of the smokers in the 5th and 6th hr after inhalation. Also, photoscintigrams showed an abnormal accumulation of particles in the large airways several hours after inhalation of the aerosol.

Diaphragm activity in obesity

DIAPHRAGM ACTIVITY DURING CARBON DIOXIDE BREATHING AND TOTAL CHEST COMPLIANCE DURING DIAPHRAGM RELAXATION WERE MEASURED IN EIGHT OBESE SUBJECTS: four with normal blood gases and four with hypercapnia and hypoxemia. Whereas there were no significant differences in the values of total chest compliance between the two groups, there were marked differences in diaphragm activity. The increase in integrated electrical activity in the diaphragm, per millimeter increment in carbon dioxide tension in the arterial blood, averaged 66 units (range: 48-90) in the obese-normal subjects and 17 units (range: 12-22) in the obese-hypoventilation subjects. These results suggest that an incapacity to increase the activity in the respiratory muscles, to levels necessary to overcome the load caused by obesity, plays a major role in the genesis of respiratory failure in obese subjects.