Assessment of individual finger muscle activity in the extensor digitorum communis by surface EMG.

The extensor digitorum communis (ED) is a slender muscle group in the dorsal forearm from which tendons arise to the index (D2), medius (D3), ring (D4), and little (D5) fingers. Limited independence has been attributed to the parts that actuate the individual fingers. However, in a detailed anatomical analysis, it was found that the ED parts to the different fingers have constant and widely spaced anatomical locations that promote independent function. These observations and the superficial muscle belly locations prompted the hypothesis that these ED parts would be individually assessable by small anatomically placed surface EMG electrodes. In the present study, this hypothesis was evaluated by measuring electromyography (EMG) from the ED parts and surrounding muscles during individual finger tapping tasks with the forearm resting on a flat surface. It was found that individual ED activity can be well measured in ED2, ED3, ED4, and extensor digiti minimi (EDM). ED3 did not give nor did its electrodes receive significant crosstalk from other ED parts. ED4 electrodes recorded an EMG level of 30 +/- 19% (mean +/- SD) ED2 EMG in D2 tapping and ED2 electrodes a level of 53 +/- 22% ED4 EMG in D4 tapping, by hypothesis mostly crosstalk. EDM electrodes may record EMG at the level of ED4 EMG in D4 tapping. In D2 tapping, the mutual ED2 and extensor indicis redundancy reflected in large intersubject EMG differences with sometimes one or the other almost silent. The results may expand the possibilities of EMG analysis and finger muscle electrostimulation in ergonomic and clinical applications.

The development of mental state attributions in women with X-monosomy, and the role of monoamine oxidase B in the sociocognitive phenotype.

We hypothesized that women with Turner syndrome (45,X) with a single X-chromosome inherited from their mother may show mentalizing deficits compared to women of normal karyotype with two X-chromosomes (46,X). Simple geometrical animation events (two triangles moving with apparent intention in relation to each other) which usually elicit mental-state descriptions in normally developing people, did not do so to the same extent in women with Turner syndrome. We then investigated the potential role in this deficit played by monoamine oxidase B enzymatic activity. MAO-B activity reflects central serotonergic activity, and by implication the functional integrity of neural circuits implicated in mentalizing. Platelet MAO-B was substantially reduced in Turner syndrome. However, contrary to prediction, in this (relatively small) sample there was no association between MAO-B enzymatic activity and mentalizing skills in participants with and without Turner syndrome.

Peak flow rate changes in O3 exposed children: spirometry vs miniWright flow meters.

We compared "miniWright" peak flow (mWPF) readings with spirometric peak expiratory flow rates (PEFR) in 91 children, aged 8-15, exposed to ambient air at a summer camp in northwestern New Jersey. mWPF measurements immediately preceded spirometry, and mWPF-PEFR differences were regressed on spirometric PEFR by child. The ratio (mWPF-PEFR)/PEFR (mean +/- SE) was -0.027 +/- 0.028 (n = 91) (NS). When subdivided into PEFR ranges, the ratios were: -0.089 +/- 0.060 (n = 17) for 2-<4 Liters/second (Lps) (p = 0.04), -0.019 +/- 0.038 (n = 50) for 4-<6 Lps (NS); and -0.000 +/- 0.044 (n = 24) for 6-<8 Lps (NS). The mWPF values were also regressed on the average ozone (O3) concentration in the previous hour, by child. The mWPF response for O3 was -6.63 +/- 0.76 mL/sec/ppb, compared to -6.78 +/- 0.73 mL/sec/ppb O3 for PEFR. Thus: 1) mWPF, with an overall underestimation of approximately 2%, is a useful surrogate for spirometric values of PEFR (although, for the smallest children studied, it underestimated peak flows by approximately 9%), and 2) the portable miniWright peak flow meter is a convenient and effective tool for characterizing changes in PEFR associated with exposures to ambient O3.

Effect of lung airway branching pattern and gas composition on particle deposition in bronchial airways: III. Experimental studies with radioactively tagged aerosol in human and canine lungs.

Particle penetration into lung airways during normal respiration is affected by the exchange of inspired air and residual gas. In this study, particle penetration during the inspiratory phase was investigated using gamma-tagged monodisperse particles (0.70, 0.90, 0.96, and 1.44 microns) suspended in various carrier gases having a wide range of kinematic viscosity. A 40-mL bolus of tagged aerosol was drawn into excised human and dog lungs at the end of a tidal breath, followed by a long breathhold to allow for complete particle deposition by sedimentation. The lungs were then fixed, sectioned, and autoradiographed to determine tidal front locations. In human lungs, particles suspended in He-O2 penetrated deeper than particles suspended in air; particles penetrated least in SF6-O2. Dog lungs, which have more asymmetrical airway branching patterns than human lungs, had no significant particle penetration differences associated with carrier gas composition. It is concluded that particle penetration during the inspiratory phase is dependent on factors that determine flow profile development, such as branching pattern and the Reynolds number of the carrier gas. The bolus front at the end of an air inspiration extended into about 10% of human lung airways of 1 mm diameter, and into about 0.1% of 0.5-mm airways. It is concluded that rapid particle penetration to 1-mm airways during high-frequency oscillatory ventilation of lung casts is due to cumulative axial core transport during multiple breathing cycles. Similarly, the dispersion of an aerosol bolus from large airways to small airways during in vivo breathholding studies appears to be due to oscillatory flow created by the heartbeat.

Effects of single- and multiday ozone exposures on respiratory function in active normal children.

Ventilatory function was measured twice daily on 46 healthy children aged 8-14 years on at least 7 days for each child during a 4-week period at a northwestern New Jersey residential summer camp in 1988. The highest 1-hr O3 concentration was 150 ppb, while the highest 12-hr H+ concentration (as H2SO4) was 18.6 micrograms/m3. The highest temperature-humidity index was 81 degrees F. The regressions of FVC, FEV1, FEF25-75, and PEFR on O3 in the hour preceding the afternoon function measurements yielded slopes essentially the same as those measured on other children at the same camp in 1984. Regressions of the changes in function between the late morning and late afternoon function measurements on average O3 concentration between them produced significant, but somewhat smaller effects, while regressions of morning function on O3 during the previous day indicated small but still significant effects. There were no significant correlations with other measured environmental variables including H+. Based on the results of this study and similar previous studies, we conclude that O3 exposures in ambient air produce greater lung function deficits in active young people in natural settings then does pure O3 in controlled chamber exposure studies because of: (1) longer exposures; (2) potentiation by other factors in the ambient exposures; (3) the persistence of effects from prior day's exposures; and (4) the persistence of a transient response associated with the daily peak of exposure. It follows that projections of likely effects in the real world from controlled chamber exposure studies should either have a large margin of safety, or the judgment of the extent of effects likely to occur among populations should be based directly on the effects observed in field studies.

Effects of heavy industrial pollution on respiratory function in the children of Cubatao, Brazil: a preliminary report.

Under a cooperative agreement between New York University and the Environmental Protection Agency, and in collaboration with the University of Sao Paulo (USP), a study is ongoing in Cubatao, Brazil, to try to establish exposure-response relationships on the impact of specific industrial effluents on respiratory function in school-age children. Cubatao, located on the coast about 44 km from the city of Sao Paulo, is surrounded by U-shaped mountains (approximately 800 m) covered with subtropical forests. Its area is approximately 160 km2, and it has a population of approximately 90,000. The geography is such that it causes a consistent diurnal land-sea breeze pattern and the opposite during the night, with low dispersion of the air pollutants. In a small area (approximately 40 km2) against the mountains there is a concentration of over 20 large plants: oil refinery; iron and steel mill; fertilizer, cement, and gypsum production; coke kilns; and chemical, paint, and many other ancillary plants. During the 1988 school year, March through June, August through November, 600 six-year-old children, attending six different kindergarten schools, underwent monthly spirometry tests. Because the children live within a 500 m radius of their school, pollution monitors were located on each of the six schools. Particles were collected using dichotomous stacked filter units placed on 20 m towers to reduce the influence of dust from unpaved roads. The units use different pore size filters for coarse, 2 to 10 microns, and fine particles, (dp) less than 2 microns, and took separate samples for day and nighttime.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of concentration and cumulative exposure of inhaled sulfuric acid on tracheobronchial particle clearance in healthy humans.

We have previously shown that 1-hr exposures to 0.5 microns sulfuric acid (H2SO4) mist at 100 and 1000 micrograms/m3 produced transient alterations of bronchial mucociliary clearance of monodispersed 7.6 and 4.2 microns mass median aerodynamic diameter gamma-tagged ferric oxide (Fe2O3) in healthy nonsmoking humans in a dose-dependent manner. To determine the role, if any, of the length of exposure, 10 healthy volunteers were exposed to 100 micrograms/m3 H2SO4 for 1 hr and 2 hr on separate occasions, 1 week apart, with measurements of their mucociliary clearance of 5.2 microns Fe2O3 particles inhaled both before and after the inhalation of the H2SO4. Their rate of bronchial mucociliary clearance was markedly reduced for both Fe2O3 aerosols, with slower clearance of the aerosol inhaled after the H2SO4 exposure. For the tagged Fe2O3 aerosol inhaled after exposure for 2 hr at 100 micrograms/m3 H2SO4, the tracheobronchial clearance halftime, (T50), tripled from control, and the reduced rate of clearance was still evident 3 hr after the end of exposure. The 1-hr 100 micrograms/m3 H2SO4 exposure doubled T50 from control, and the reduced rate of clearance lasted for about 2 hr after the end of exposure. These results indicate that the effect of doubling the length of exposure was as great or greater than an order of magnitude increase in the concentration of H2SO4.

Effects of ambient ozone on respiratory function in healthy adults exercising outdoors.

The effect of exposure to ozone (O3) in ambient air on respiratory function was studied in 30 healthy adult nonsmokers engaged in a regular daily program of outdoor exercise in Tuxedo, NY during the summer of 1985. Each subject did the same exercise each day, but exercise intensity and duration varied widely between subjects, with minute ventilation ranging from 20 to 153 L and duration ranging from 15 to 55 min. Spirometry was performed immediately before and after each exercise period. O3 concentrations during exercise ranged from 21 to 124 parts per billion (ppb). All measured functional indexes showed significant (p less than 0.01) O3-associated mean decrements with FVC at -2.1 ml/ppb, FEV1 at -1.4 ml/ppb, PEFR at -9.2 ml/s/ppb, FEF25-75 at -6.0 ml/s/ppb, and FEV1/FVC at -0.038%/ppb. Mean decrements were smaller for 10 subjects with minute ventilations greater than 100 L than for 10 other subjects with minute ventilations between 60 and 100 L or for the 10 subjects with minute ventilations below 60 L. Overall, the functional decrements were similar in magnitude to those we have seen in children engaged in supervised recreational programs in summer camps. For 10 subjects with minute ventilations comparable to those used in controlled 1- and 2-h exposures to O3 in purified air in chambers (50 to 80 L), the effects were about twice as large as those reported for the chamber studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of lung airway branching pattern and gas composition on particle deposition. II. Experimental studies in human and canine lungs.

The recovery of monodisperse inhaled particles from humans in vivo and from excised human and canine lungs was measured after a single breath for particles suspended in air and in mixtures of He or SF6 with O2. Comparisons were made using the unique particle sizes for which the intrinsic particle motions in air and each mixture were identical, so that differences in recovery could be associated with differences in convective flow. For the in vivo tests, only mixtures with 20% O2 were used, while for the excised lungs, mixtures with 10% O2 were also used. In humans in vivo and in excised human lungs, there was significantly greater deposition from He-O2 mixtures and less deposition from SF6-O2 mixtures, with no differences between the in vivo and the excised lung results for the 80-20 mixtures. For the canine lungs, there were no differences in deposition between air and any He or SF6 mixture. The interspecies differences are consistent with the hypothesis that particle exchange between tidal and residual lung gas is dependent on the distance into each airway that is needed to establish a stable flow profile. The more symmetrical branching of human lung airways causes the entry flow into daughter airways to be highly asymmetric, and flow profile rearrangement is greater than that in the monopodal canine lung.

Effects of ambient ozone on respiratory function in active, normal children.

Respiratory functions were measured on a daily basis by spirometry over a period of 4 wk at a summer camp at Fairview Lake in northwestern New Jersey. Fifty-three boys and 38 girls 8 to 15 yr of age participated in the study on at least 7 days; 37 children were in residence for 4 wk, 34 for the first 2 wk only; and 20 for the last 2 wk. There were 72 whites, 15 blacks, 3 Asians, and 1 Hispanic in the study group. Multiple regression analyses indicated that the O3 concentration in the previous hour, the cumulative daily O3 exposure during the hours between 9 A.M. and the function measurement, ambient temperature, and humidity were the most explanatory environmental variables for daily variations in function, with the 1 - h O3 concentration having the strongest influence. Linear regressions were performed for each child between O3 concentration and function, and all average slopes were significantly negative (p less than 0.05) for FVC, FEV1, PEFR, and FEF25-75 for all children, and for boys and girls separately. Comparable results were obtained in data subsets (i.e., children studied during the first or second 2 wk only, and for data sets truncated at O3 less than 80 and O3 less than 60 ppb). The average regression slopes (+/- SE) for FVC and FEV1, respectively, were -1.03 +/- 0.24 and -1.42 +/- 0.17 ml/ppb, whereas for PEFR and FEF25-75 they were -6.78 +/- 0.73 and -2.48 +/- 0.26 ml/s/ppb.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of orally administered orciprenaline on tracheobronchial mucociliary clearance.

The relative effects of beta-2-adrenergic stimulation of mucociliary transport in the trachea and the bronchial airways was determined in 12 healthy non-smoking males using radioaerosol techniques with and without the oral administration of 20 mg of orciprenaline. Orciprenaline increased tracheal mucociliary transport rates (TMTR) from a control mean of 4.4 +/- 2.4 mm/min to 6.6 +/- 4.0 mm/min (p less than 0.01), but the percentage of particles cleared from the lung in 2 h was not significantly different in the drug study (44 +/- 14%) compared to the control study (48 +/- 19%). Furthermore, a strong positive correlation existed between TMTR and bronchial clearance that was lost after administration of orciprenaline. This study demonstrates that low doses of orally administered orciprenaline increased tracheal mucociliary transport but not bronchial clearance in healthy adults.

Effects of submicrometer sulfuric acid aerosols on mucociliary transport and respiratory mechanics in asymptomatic asthmatics.

The effects of a 1-hr inhalation of submicrometer sulfuric acid (H2SO4) aerosols via nasal mask on tracheobronchial mucociliary particle clearance and respiratory mechanics were studied in ten subjects with asthmatic histories. A brief inhalation of monodisperse 3.9-micron 99mTc-tagged Fe2O3 aerosol preceded the 1-hr H2SO4 (at 100, 300, and 1000 micrograms/m3) or a sham exposure. Thoracic retention of the gamma-tagged Fe2O3 was measured using external radiation detectors. Respiratory function was measured before, and 15 min and 3 hr after the H2SO4 or sham exposure. After exposure to 1000 micrograms/m3 of H2SO4, the six subjects not on routine medication exhibited a transient slowing of mucociliary clearance and also decrements in sGaw, FEV1/FVC, MMEF, and V25 (P less than 0.05) in both sets of measurements. The four asthmatics on daily medication exhibited stepwise mucociliary clearance that was too variable to allow detection of any H2SO4 effect on clearance. The 1000 micrograms/m3 of H2SO4 did produce decrements in V25 (P less than 0.05), but the variability of the other respiratory parameters in this small group was too great to permit detection of changes. Mucociliary clearance rates in both groups in the sham exposure tests were significantly slower than those of healthy nonsmokers studied previously using the same protocols. The extent of mucociliary clearance slowing following the 1000 micrograms/m3 exposure in the nonmedicated subjects was similar to that in the healthy nonsmokers. This similar change, from a reduced baseline rate of clearance, together with the significant change in respiratory function, indicate that asymptomatic asthmatics may respond to H2SO4 exposures with functional changes of greater potential health significance than do healthy nonsmokers.

Influence of airway and airspace sizes on particle deposition in excised donkey lungs.

Tests of aerosol deposition with breath holding and of lung function were performed on the excised lungs of three donkeys following regional in vivo radioaerosol deposition tests. Corrosion casts were made of the lungs to determine the dimensions of the tracheobronchial (TB) tree, and histological sections were taken to determine average alveolar airspace size. Static lung function tests, i.e., static compliance and specific compliance (Cstat and Cspec), agreed well with the predicted and reported in vivo values, as did the slope of Phase III from the single breath nitrogen washout (SBNW). Dynamic tests, i.e., dynamic compliance (Cdyn) and pulmonary resistance (Rpulm), displayed larger inter- and intra-subject variation, and showed poor agreement with reported in vivo values. Breathholding tests using 0.55 micron diameter aerosol indicated a mean respiratory airspace dimension of 0.16 mm, while the mean alveolar diameter from the lung sections was 0.19 mm. Breathholding tests with 1.18 micron aerosol indicated a mean small airway size of 0.65 mm, corresponding to the sizes of small airways on the corrosion casts. The donkeys have larger central airways but smaller peripheral airways than humans, and greater tracheobronchial deposition efficiency for 5 micron diameter particles. Tracheobronchial deposition in donkeys appears to be concentrated more distally than in humans, and may be related to the monopodal airway branching pattern in the former.

Dose-dependent effects of submicrometer sulfuric acid aerosol on particle clearance from ciliated human lung airways.

We previously showed that 1 hr exposures to submicrometer sulfuric acid (H2SO4) aerosol at 100 and 1000 micrograms/m3 altered the bronchial mucociliary clearance of monodisperse 7.6 micron MMAD 99mTc-labelled ferric oxide (Fe2O3) in healthy, nonsmoking humans. The 7.6 micron particles were primarily deposited in the larger bronchial airways, where submicrometer H2SO4 has very little deposition. To determine the extent that submicrometer H2SO4 aerosol affects clearance from the more distal ciliated airways, we measured the clearance of a monodisperse 4.2 micron MMAD Fe2O3 aerosol in eight other healthy nonsmoking subjects. A greater fraction of 4.2 micron particles deposited in distal conductive airways. Bronchial mucociliary clearance was slower following 1 h nasal H2SO4 inhalations at 100, 300 and 1000 micrograms/m3 than after sham exposures, while mucociliary transport rates within the trachea and indices of respiratory mechanics were unchanged. A comparison of the effects of 1 h exposures at 100 micrograms/m3 on the clearance of 7.6 and 4.2 micron particles suggests greater physiological response in distal ciliated airways than in larger central airways.

Effects of drugs on mucociliary transport in the trachea and bronchial airways.

Pharmacologically active agents may change transport rates regionally within the airways of the lung, as well as affect the overall magnitude of the clearance of inhaled deposited radioaerosols. To investigate these possibilities the response of ethanol on pulmonary retention was determined and the responses of both the trachea and bronchial airways were measured after either oral administration of metaproterenol or inhalation of sulfuric acid mist. In the healthy nonchallenged lung, the velocity of mucociliary transport in the trachea was related to the percentage of activity cleared from the lung in two hours. Indices representing different portions of the pulmonary retention curve were also correlated. Changes in this interdependence of mucociliary transport within airways were produced by all agents. Metaproterenol increased tracheal mucus velocity but not lung clearance. Alcohol changed pulmonary retention in both magnitude and direction depending on the individual, resulting in an increase in variability of pulmonary mucociliary clearance between persons. Thus, to evaluate the effects of drugs or pollutants on the lower respiratory tract, measurements of mucociliary transport should be made in both the trachea and the bronchial airways.

The effects of irritant aerosols on mucus clearance from large and small conductive airways.

The effects of one hour exposures of healthy nonsmoking human volunteers to submicrometer H2SO4 droplets via nasal mask on tracheobronchial mucociliary particle clearance were studied using two different sized monodisperse gamma-tagged Fe2O3 test aerosols. The larger sized Fe2O3 aerosol, 7.5 micrometers AMAD, was deposited primarily in the larger bronchial airways, while the smaller 4 micrometers AMAD aerosol had a much greater fraction deposited in the smaller and more distal conductive airways. Thoracic retention of the Fe2O3 aerosols as a function of time after a brief inhalation was measured with external collimated radiation detectors. At the highest H2SO4 exposure, 1,000 micrograms/m3, there was a pronounced transient slowing of bronchial mucociliary clearance of both the 7.5 and 4 micrometers Fe2O3. On the other hand, at the lowest H2SO4 concentration, 100 micrograms/m3, there was a marked acceleration of the clearance of the 7.5 micrometers Fe2O3, but a slowing of the clearance of the 4 micrometers Fe2O3. Thus, submicrometer H2SO4, which deposits primarily in the distal airways, can slow mucociliary clearance in those airways. In the larger airways, where its deposition is minimal, the H2SO4 can, at the same time, accelerate mucus transport.

Coordination of mucociliary transport in human trachea and intrapulmonary airways.

A wide range of both mucus velocities in the trachea and rates of bronchial mucociliary clearance have been measured in humans. To investigate the coordination of mucociliary transport in the intrapulmonary and extrapulmonary airways, simultaneous measurements of tracheal mucus velocity and lung clearance were made in 22 healthy nonsmoking adults. Each subject inhaled several breaths of an iron oxide aerosol tagged with 99mTc. Measurements of retained activity in the right lung were made for 2.25 h with a pair of 5 x 2 in. NaI (T1) detectors. Tracheal mucociliary transport rates (TMTR) were measured with a probe containing six vertically aligned rectangular NaI (T1) detectors. The mean TMTR was 5.1 +/- 2.9 mm/min. The mean time for the first bolus to be detected on the multidetector probe (large airway transit time, LATT) was 52 +/- 24 min. At this time the percent cleared (Bi) was 24 +/- 15% and the rate of clearance (Bi) was 0.64 +/- 0.35%/min. The mean percent cleared within a 2-h interval (B120) was 51 +/- 22%. The TMTR was closely correlated with Bi and Bi with B120. The TMTR was also correlated to B120, but not closely correlated with LATT. It is suggesting that coordination of mucus transport throughout the airways of the lung represents the nonchallenged state and is responsible for the maintenance of normal bronchial toilet.

Remanent magnetic fields for measuring particle retention and distribution in the lungs.

A relatively inexpensive method for the noninvasive in vivo detection of ferrimagnetic particles within the lungs of a large laboratory animal, viz., the donkey, is described. The particles were neutron activated prior to inhalation, which permitted a comparison of two different retention measurements for the same particles, i.e., a well-characterized radiological-detection method concurrent with the newer magnetic-field technique. The long-term clearance of the particles from the lung was monitored in terms of the reduction in initial remanent field following magnetization, and the reduction in gamma-ray flux reaching the collimated scintillation detectors. Comparison of the measurements confirmed that the reduction of the initial remanent-field values with time was due to particle clearance rather than a change of the iron state to a nonmagnetic form. This validates previous reports that particle clearance studies can be performed using remanent magnetic-field measurement techniques. However, remanent magnetic-field measurements require careful design and interpretation, since they are highly sensitive to the distribution of the particles within the effective viewing field.