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Biomedical subjects

D J Hendrick

Publications and source records attributed to D J Hendrick.

At least 73 records · Page 4Linked to original sources
PubMed1990

Jet and ultrasonic nebuliser output: use of a new method for direct measurement of aerosol output.

Output from jet nebulisers is calibrated traditionally by weighing them before and after nebulisation, but the assumption that the weight difference is a close measure of aerosol generation could be invalidated by the concomitant process of evaporation. A method has been developed for measuring aerosol output directly by using a solute (fluoride) tracer and aerosol impaction, and this has been compared with the traditional weight loss method for two Wright, six Turbo, and four Micro-Cirrus jet nebulisers and two Microinhaler ultrasonic nebulisers. The weight loss method overestimated true aerosol output for all jet nebulisers. The mean aerosol content, expressed as a percentage of the total weight loss, varied from as little as 15% for the Wright jet nebulisers to 54% (range 45-61%) for the Turbo and Micro-Cirrus jet nebulisers under the operating conditions used. In contrast, there was no discrepancy between weight loss and aerosol output for the ultrasonic nebulisers. These findings, along with evidence of both concentrating and cooling effects from jet nebulisation, confirm that total output from jet nebulisers contains two distinct fractions, vapour and aerosol. The vapour fraction, but not the aerosol fraction, was greatly influenced by reservoir temperature within the nebuliser; so the ratio of aerosol output to total weight loss varied considerably with temperature. It is concluded that weight loss is an inappropriate method of calibrating jet nebuliser aerosol output, and that this should be measured directly.

Aerosols↗
PubMed1990

The reversible effect of lignocaine on the stimulated metabolic activity of bronchoalveolar lavage cells.

Lignocaine concentrations were measured in the aspirate from a low volume (100 ml) bronchoalveolar lavage (BAL) in twenty patients who had received topical 4% lignocaine as required, and compared to those found in the aspirate from a 180 ml BAL in ten patients who had received 1.5% isotonic lignocaine. The median BAL supernatant lignocaine concentration was significantly lower at 0.14 mM (range 0.07-0.44 mM) in the group who received 1.5% lignocaine, compared to 1.08 mM (range 0.03-7.05 mM) in those given 4% lignocaine (p less than 0.01). The effect of increasing concentrations of lignocaine on BAL neutrophil and pulmonary macrophage metabolic activity, as assessed by latex-stimulated luminol- and lucigenin-amplified chemiluminescence (CL), respectively, in mixed BAL cell populations, were measured following preincubation of "washed" harvested BAL cells with 0.4-8.0 mM lignocaine. There was no demonstrable decline in either cell activity with lignocaine concentrations of up to 2 mM, with dose-dependent inhibition of both above this threshold. Cell viability was unaffected. In a further experiment, the inhibition induced by 8 mM lignocaine on both pulmonary macrophage (lucigenin-amplified CL of harvested BAL cells) and isolated peripheral blood neutrophil metabolic activity was completely reversed by a single "wash", following both 30 and 60 min incubations at 4 degrees C, which was equivalent to resuspending harvested BAL cells in fresh medium after separation from BAL supernatant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The relative contribution of bronchoalveolar macrophages and neutrophils to lucigenin- and luminol-amplified chemiluminescence.

The relationship between differential cell counts and latex-stimulated luminol and lucigenin-amplified chemiluminescence (CL) was investigated by mixing alveolar macrophages (AM) obtained at bronchoalveolar lavage (BAL) with allogeneic peripheral blood neutrophils (PMN) in varying proportions. In 5 non-asthmatic subjects, the mean luminol-amplified CL increased linearly from 2.1 (0.9 SEM) x 10(5) counts per second (cps) with less than 2% PMN, greater than 96% AM to 47.3 (11.1 SEM) x 10(5) cps with greater than 94% PMN, 0% AM (r = 0.996, p less than 0.001). The regression had a y-intercept indistinguishable from 0 cps, suggesting that luminol-amplified CL exclusively reflected PMN activity. Using the same technique, the mean lucigenin-amplified CL showed a fall from 35 (2.3 SEM) x 10(5) cps with a cell population of greater than 96% AM, less than 2% PMN to 20 (2.3 SEM) x 10(5) cps with 0% AM, greater than 94% PMN. Both PMN and AM appeared to contribute to lucigenin-amplified CL, with AM contributing approximately 1.7 times as much activity per cell as PMN. Lucigenin-amplified CL appeared to be an appropriate technique for measuring AM activity when the proportion of PMN in mixed cell populations was small. A linear relationship was found between percent PMN count and luminol-amplified CL measured in a mixed BAL cell population from asthmatic subjects (p less than 0.01) and non-asthmatic controls (p less than 0.01). The slope of this regression line was significantly greater for subjects with asthma than for control subjects (p less than 0.01), suggesting a uniform increase in PMN activity in cells obtained from asthmatic airways.

Acridines↗
PubMed1990

Platelet-activating factor in bronchoalveolar lavage fluid from asthmatic subjects.

Bronchoalveolar lavage (BAL) was performed on 28 asthma patients, 7 patients with emphysema and 11 control subjects. Total and differential cell counts were performed and cellular metabolic activity was assessed using luminol and lucigenin amplified chemiluminescence. BAL supernatants were assayed for platelet-activating factor (PAF) and lyso-PAF using a sensitive guinea-pig bioassay. Eight of the asthma patients but none of the emphysema patients or control subjects had PAF in their BAL fluid. Lyso-PAF was measurable in BAL fluid in most subjects and no differences were detected between groups. Among the asthma patients, the presence of PAF in BAL supernatant was significantly associated with a combination of low neutrophil and high lymphocyte counts (p less than 0.05) and with macrophage metabolic activity as assessed by lucigenin chemiluminescence (p less than 0.05).

Adolescent↗
PubMed1989

Occupational asthma due to a repair process for polyethylene-coated electrical cables.

We report the case of an electrical cable repairer who presented with symptoms suggestive of occupational asthma. A supervised workplace challenge test confirmed this diagnosis and laboratory challenge studies implicated heated polyethylene repair tape containing the chemical cross-linking agent dicumyl peroxide as the cause. Similar cross-linking processes are widely used in the cable manufacturing industry and the possibility of occupational asthma occurring in other settings may need to be considered.

Adult↗
PubMed1989

Lymphocyte subsets in bronchoalveolar lavage fluid obtained from stable asthmatics, and their correlations with bronchial responsiveness.

Bronchial responsiveness to methacholine (PD20 FEV1) was assessed in 22 asthmatic subjects approximately 5 days prior to bronchoalveolar lavage (BAL). A PD20 FEV1 could not be attained in 20 matched controls with normal pulmonary function. BAL was performed in all subjects, 3 x 60 ml aliquots of buffered saline being introduced into a segment of the middle lobe and immediately aspirated into siliconized glassware at 4 degrees C. After filtration, cells were counted, and the cell pellet resuspended in medium 199. Cytospin slides were prepared and a differential cell count performed. Lymphocyte subsets were identified by labelling further cytospin preparations with specific monoclonal antibodies (Leu series) against T3, T4, T8 and B cell markers, followed by a fluorescent antibody marker. The slides were coded, and 100 lymphocytes were then randomly scanned for fluorescence on each cytospin preparation. The median total lymphocyte counts were significantly greater in the asthmatic subjects, but this increase was confined to the T cell subgroups. The mean T4/T8 ratio was similar in asthmatic (1.51) and control (1.45) subjects. Log PD20 FEV1 correlated positively with total lymphocyte counts (r = 0.42, P less than 0.05), and with total T8 counts (r = 0.60, P less than 0.05). Correlations between bronchial responsiveness and T3, T4 and B lymphocyte numbers all failed to reach significance, and there was no correlation with T4/T8 ratios. The increase in BAL lymphocyte counts in asthma appears to be due to an absolute increase in T cell subsets, especially the T8 lymphocyte subgroup, and is most marked in mild asthmatics.

Adolescent↗
PubMed1989

Refractory period following bronchoconstriction provoked by histamine in asthmatic subjects.

To determine whether refractoriness to histamine induced bronchoconstriction occurs, 20 asthmatic subjects aged 19-50 years were tested. Subjects underwent two histamine challenge tests (1 and 2) on the same day, the second one being given 45-60 minutes after the first, once the FEV1 after test 1 had returned spontaneously to within 90% of baseline. A further "control" histamine challenge test was carried out on a different day at the same time (+/- 2 hours) as test 1. Bronchial responsiveness was recorded as the cumulative dose (microgram) of histamine provoking a 20% fall in FEV1 (PD20), and the ratio PD20 test 2:PD20 test 1 was used to assess refractoriness. The median value of this ratio (2.20) was significantly greater than 1 (p = 0.003), indicating refractoriness at the time of test 2. By contrast the median ratio PD20 control:PD20 test 1 of 1.03 was not significantly different from 1. Refractoriness could not be accounted for by failure to regain the initial baseline FEV1, though such failure may have exaggerated the effect. An increase in PD20 with the second test was observed uniformly in subjects with moderate or high initial PD20 values but not in those with low values. This suggests that there may be a PD20 threshold of the order 25-100 micrograms for refractoriness to occur. Refractoriness could exert an important confounding effect in investigations in which repeated histamine tests are carried out at short intervals.

Adult↗
PubMed1988

The use of sequential doses of inhaled histamine in the measurement of bronchial responsiveness: cumulative effect and distortion produced by shortening the test protocol.

We have evaluated a shortened protocol for measuring bronchial responsiveness to histamine. This safely eliminates unnecessarily low doses from a standard doubling dose sequence (i.e., full protocol) so that the dose provoking the definitive 20% decrement in FEV1 (PD20) is usually reached within two or three dose increments. In 20 subjects with asthma tested with both protocols, the ratio of geometric mean PD20 short protocol (86.8 micrograms) to PD20 full protocol (45.7 micrograms) was significantly greater than 1 when the results were expressed on a noncumulative scale (1.90 versus 1; p less than 0.001). When PD20 was expressed on a cumulative scale, the discordance was less striking (123.7 versus 89.2 micrograms, respectively), but this ratio (1.39) was still significantly greater than 1 (p = 0.007). By contrast, duplicated measurements of PD20 with the full protocol and the cumulative scale elicited a ratio of geometric mean PD20 day 1 (63.0 micrograms) to PD20 day 2 (67.0 micrograms) of 0.94, which was not significantly different from 1. Thus, the bronchoconstrictor effect of histamine depends on both the cumulative dose and the number of component doses. We conclude (1) that PD20 histamine is more nearly accurately expressed on a cumulative than on a noncumulative scale and (2) that histamine is less suitable for shortened protocols than methacholine because a reduction in the number of component doses produces significant distortion of the PD20 result.

Administration, Inhalation↗
PubMed1988

The relationship between bronchial responsiveness to methacholine and bronchial responsiveness to histamine in asthmatic subjects.

There is widespread belief that methacholine responsiveness in asthmatic subjects is closely related to histamine responsiveness, and that the two agents may be used interchangeably in the measurement of non-specific bronchial responsiveness (NSBR). Because this view has been challenged, we have examined the repeatability of measurements of bronchial responsiveness to methacholine and histamine and the relationship between them, in groups of 20 adult asthmatic subjects. Bronchial responsiveness was expressed as the cumulative dose (in both micrograms and mmols) provoking a 20% fall in FEV1 (PD20). The predicted 95% confidence limits for the second PD20 measurement of a further pair were within the range 0.5-2.0 x first PD20 for both agents. When the two agonists were compared in the same subjects, a significant difference in potency was noted (ratio of geometric means PD20.methacholine to PD20.histamine 2.19 [micrograms], 3.43 [mmols]; p = 0.0003). Furthermore, the variance of the differences of the pairs of log PD20.methacholine and PD20.histamine measurements was found to be significantly greater than that of either the paired methacholine measurements or the paired histamine measurements (p less than 0.01). We conclude firstly that methacholine is a less potent bronchoconstrictor than histamine and secondly that, while inhalation tests with either agent broadly reflect the degree of NSBR, they measure different phenomena and cannot be used interchangeably even after allowance is made for the difference in potency.

Adult↗
PubMed1988

An assessment of methacholine inhalation tests in elderly asthmatics.

We have assessed the feasibility and value of measuring nonspecific bronchial responsiveness to methacholine in investigation of asthma in the elderly. Results from duplicated tests in 20 subjects aged 65-82 years were expressed as dose provoking a 20% decrement in 1 second forced expiratory volume (PD20.FEV1) or peak expiratory flow (PD20.PEF). Repeatability for PD20.FEV1 was satisfactory but less good than in younger subjects, 95% confidence limits being 0.39-2.57 and 0.52-1.91, respectively, x initial PD20. For PD20.PEF, confidence limits were wider (0.26-3.91 x initial PD20) but multiple PEF measurements were better tolerated than those of FEV1, which commonly caused fatigue and dizziness. PD20.FEV1 and PD20.PEF correlated closely (r = 0.95, P less than 0.0001) and both predicted bronchodilatation following a 6-week course of inhaled corticosteroid and beta agonist. This was not predicted by the response to a single dose of beta agonist. We conclude that measurement of bronchial responsiveness is feasible and clinically valuable in elderly subjects.

Aged↗
PubMed1988

Assessment of pulmonary macrophage and neutrophil function in sequential bronchoalveolar lavage aspirates in sarcoidosis.

Bronchoalveolar lavage was performed in eight patients with biopsy proved sarcoidosis and eight control subjects matched for age and smoking habit, three sequential 60 ml aliquots of sterile saline being used. Each aliquot was aspirated and analysed separately to determine total and differential cell counts. Cellular metabolic activity was stimulated with latex and measured by means of luminol enhanced chemiluminescence to assess neutrophil activity and lucigenin enhanced chemiluminescence to assess macrophage activity. In control subjects mean total cell counts were significantly greater in the second aspirate than in the first, but fell slightly in the third. Similarly, in the patients with sarcoidosis mean total cell counts increased from aspirate 1 to a maximum in aspirate 2, before falling again marginally in aspirate 3. The only significant difference in cell counts between patients with sarcoidosis and controls was an approximately threefold increase in total lymphocyte counts in the former in each of the three aspirates. Luminol chemiluminescence was similar in patients with sarcoidosis to that in controls in the first aspirate, but was significantly greater in the second and third aspirates. Lucigenin chemiluminescence was also significantly greater in the second and third aspirates only. Thus in patients with sarcoidosis lymphocyte numbers are increased in all three aspirates whereas cellular metabolic activity is increased to a greater extent in later aspirates, which may reflect events occurring in the periphery of the lung segment.

Acridines↗
PubMed1988

Occupational asthma due to sodium iso-nonanoyl oxybenzene sulphonate, a newly developed detergent ingredient.

Research with sodium iso-nonanoyl oxybenzene sulphonate (SINOS) for use in a detergent product was complicated by the development of asthma in an atopic 38 year old laboratory technician. Inhalation challenge tests with nebulised SINOS solutions over a dose range of 0.01-32 micrograms gave reproducible late asthmatic reactions after the higher doses and an increase in bronchial responsiveness to methacholine. The magnitude of the late reaction was related to the challenge dose.

Adult↗
PubMed1988

Number and activity of inflammatory cells in bronchoalveolar lavage fluid in asthma and their relation to airway responsiveness.

Bronchial responsiveness to inhaled methacholine was measured four to six days before fibreoptic bronchoscopy in 22 asthmatic patients (10 smokers) and 20 control subjects (12 smokers). The asthmatic patients had a baseline FEV1 greater than 60% predicted and a PD20FEV1 (provocative dose of methacholine causing a 20% fall in FEV1) of 0.006-3.7 mg. The 20 control subjects had normal pulmonary function and a PD20FEV1 above the maximum cumulative dose of methacholine of 6.4 mg. Bronchoalveolar lavage of a middle lobe segment (lingula in four subjects) was performed with three sequential 60 ml aliquots of sterile saline. Cellular metabolic activity was stimulated with latex in aliquots of resuspended cells, and measured by means of luminol enhanced chemiluminescence to assess neutrophil activity and lucigenin enhanced chemiluminescence to assess macrophage activity. Mean absolute total cell counts were similar in the asthmatic and control groups but there were differences in differential cell counts, with a significant increase in eosinophil (p less than 0.05) and lymphocyte (p less than 0.005) counts in asthma. PD20FEV1 was negatively correlated with percentage neutrophil counts (p less than 0.005). Luminol enhanced chemiluminescence/1000 neutrophils was increased about twofold in asthmatic subjects (p less than 0.001), but was not correlated with PD20FEV1 Lucigenin enhanced chemiluminescence/1000 macrophages was increased nearly fourfold in asthmatic patients (p less than 0.001) and showed a negative correlation with PD20FEV1 (p less than 0.01). The macrophage count was increased twofold in current smokers in both groups, but other cell numbers were not altered significantly. Smoking did not affect cellular metabolic activity in either group. This study supports the idea that an inflammatory process is present in the airways of those with asthma, and suggests a relation between bronchial responsiveness and both neutrophil numbers and macrophage activity.

Adolescent↗
PubMed1988

Fluid dynamics during bronchoalveolar lavage.

A series of related studies were designed to investigate and quantify the degree of fluid exchange between the lung segment and the interstitium or pulmonary circulation that occurred during a standardized bronchoalveolar lavage (BAL). In 5 subjects undergoing a 3 x 60 ml BAL, the dilution of introduced fluid was calculated at approximately 25% using both technetium colloid and methylene blue. Thus, there was a total dilution volume of about 225 ml. In the same experiment, tritiated water was incorporated into the introduced fluid, and the degree of dilution of tritium in the aspirate was compared with that of the other 2 markers. The dilution of tritium was greater than anticipated, suggesting that around 55 ml of water had effluxed from the lung segment during BAL. The total fluid gain by the segment during BAL was thus approximately 100 ml (44% of the dilution volume), although the contribution of fluid resident in the lung prior to BAL to this volume was not known. The 3 x 60 ml BAL procedures were performed in a further 5 patients 12 h after they had received tritiated water orally. The concentration of urea, a putative "endogenous marker" of dilution, was assayed simultaneously in plasma and aspirate. From these values the fluid normally resident in the lung segment was calculated to contribute at most about 2% to the total aspirated volume. A median of 39% of the 85 ml aspirated was calculated to have come from the circulation or surrounding interstitium by simultaneous measurements of the concentrations of tritium in plasma and lavage aspirate.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Water↗
PubMed1987

Anatomical distribution of bronchoalveolar lavage fluid as assessed by digital subtraction radiography.

A digital subtraction imaging technique was used to visualise directly the anatomical distribution of 3 X 60 ml aliquots of saline containing a low concentration of radio-opaque dye, introduced sequentially into a segment of the middle lobe. It was possible to estimate the relative movement of fluid within the segment during the sequential aspiration of each of these aliquots. The first 60 ml aliquot introduced stayed close to the bronchoscope and probably sampled only the proximal airways. With the introduction of cumulative volumes of 120 ml or more, the fluid filled the segment more evenly. Aspiration then moved fluid back from the periphery, implying that the aspirate had also lavaged both distal airways and alveoli.

Adult↗